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Posted to users@openjpa.apache.org by Lars Vogel <la...@googlemail.com> on 2008/04/14 09:04:16 UTC
JPAAnnotations on the instance variable or on the getter
Hi,
my understanding so far was that it doesn't matter if I have the annotation
on the instance variable or on the the getter method of the class.
It that true? Because I have an example where I receive a Null pointer
exception if I put the annotation on the instance variable and not on the
getter. Example below. The error occurs during the access of the JobList
variable. The whole project is attached in case someone would like to have a
look. For testing just exchange PersonNew.java with Person.java.
Best regards, Lars
----------
This works:
------------------------------
package datamodel.impl;
import java.util.ArrayList;
import java.util.List;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.OneToMany;
import javax.persistence.OrderBy;
import javax.persistence.Transient;
import org.apache.openjpa.persistence.PersistentCollection;
import datamodel.IPerson;
@Entity
public class PersonNew implements IPerson {
private String id;
private String firstName;
private String lastName;
private String nonsenseField = "";
private List<Job> jobList = new ArrayList<Job>();
private List<String> nickNameList = new ArrayList<String>();
@Id
@GeneratedValue(strategy=GenerationType.SEQUENCE)
public String getId() {
return id;
}
public void setId(String Id) {
this.id = Id;
}
public String getFirstName() {
return firstName;
}
public void setFirstName(String firstName) {
this.firstName = firstName;
}
// Leave the standard column name of the table
public String getLastName() {
return lastName;
}
public void setLastName(String lastName) {
this.lastName = lastName;
}
@Transient
public String getNonsenseField() {
return nonsenseField;
}
public void setNonsenseField(String nonsenseField) {
this.nonsenseField = nonsenseField;
}
@OneToMany
public List<Job> getJobsList() {
return this.jobList;
}
public void setJobsList(List<Job> nickName) {
this.jobList = nickName;
}
@PersistentCollection
@OrderBy
public List<String> getNickNameList() {
return nickNameList;
}
public void setNickNameList(List<String> nickNameString) {
this.nickNameList = nickNameString;
}
}
This results in an error:
package datamodel.impl;
import java.util.ArrayList;
import java.util.List;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.OneToMany;
import javax.persistence.OrderBy;
import javax.persistence.Transient;
import org.apache.openjpa.persistence.PersistentCollection;
import datamodel.IPerson;
@Entity
public class Person implements IPerson {
@Id
@GeneratedValue(strategy=GenerationType.SEQUENCE)
private String id;
private String firstName;
private String lastName;
@Transient
private String nonsenseField = "";
@OneToMany
private List<Job> jobList = new ArrayList<Job>();
@PersistentCollection
@OrderBy
private List<String> nickNameList = new ArrayList<String>();
public String getId() {
return id;
}
public void setId(String Id) {
this.id = Id;
}
public String getFirstName() {
return firstName;
}
public void setFirstName(String firstName) {
this.firstName = firstName;
}
// Leave the standard column name of the table
public String getLastName() {
return lastName;
}
public void setLastName(String lastName) {
this.lastName = lastName;
}
public String getNonsenseField() {
return nonsenseField;
}
public void setNonsenseField(String nonsenseField) {
this.nonsenseField = nonsenseField;
}
public List<Job> getJobsList() {
return this.jobList;
}
public void setJobsList(List<Job> nickName) {
this.jobList = nickName;
}
public List<String> getNickNameList() {
return nickNameList;
}
public void setNickNameList(List<String> nickNameString) {
this.nickNameList = nickNameString;
}
}
Re: JPAAnnotations on the instance variable or on the getter
Posted by Lars Vogel <la...@googlemail.com>.
Hi Mike,
I'll give it a try. Thank you for your answer. Best regards, Lars
2008/4/21 Michael Dick <mi...@gmail.com>:
> Hi Lars,
>
> It looks like you aren't hitting the same problem I was.
>
> Are you running the PCEnhancer tool to enhance your entity classes? I've
> been able to reproduce the problem on OpenJPA 1.0.2 if the entities aren't
> enhanced prior to running the test.
>
> You'll see something like this in the logs if the entities haven't been
> enhanced :
> 1756 people INFO [main] openjpa.Enhance - Creating subclass for
> "[class
> datamodel.impl.Person, class datamodel.impl.Job]". This means that your
> application will be less efficient and will consume more memory than it
> would if you ran the OpenJPA enhancer. Additionally, lazy loading will not
> be available for one-to-one and many-to-one persistent attributes in types
> using field access; they will be loaded eagerly instead.
>
> Could you try enhancing the entities and see if that resolves the problem?
> The OpenJPA manual covers enhancement at the following location :
>
> http://openjpa.apache.org/docs/latest/manual/manual.html#ref_guide_pc_enhance
>
> -Mike
>
>
> On Mon, Apr 21, 2008 at 1:21 AM, Lars Vogel <la...@googlemail.com>
> wrote:
>
> > Hi Mike,
> >
> > even if I remove the @OrderBy annotation the error occurs. It seems that
> > JPA
> > cannot access the content of the list List<Jobs>. Please see my response
> > to
> > Janko.
> >
> > Best regards, Lars
> >
> >
> > 2008/4/16, Michael Dick <mi...@gmail.com>:
> > >
> > > Hi Janko and Lars
> > >
> > > I'd forgotten about the restriction. When I saw that there was
> different
> > > behavior between property and field access I guessed it was something
> > with
> > > the access level of his fields - maybe something in the subclassing
> > > support.
> > >
> > >
> > > I took a closer look at the example and I think the problem of is that
> > it
> > > uses a List of Strings as the target of the @OrderBy annotation. The
> > > target
> > > of the @OrderBy annotation is expected to be an entity which is
> causing
> > a
> > > NPE.
> > >
> > > I'm not sure it was the same NPE that Lars hit though. Here's what
> I've
> > > been
> > > seeing (with OpenJPA 1.2.0-SNAPSHOT):
> > >
> > > java.lang.NullPointerException
> > > at
> > >
> org.apache.openjpa.meta.FieldMetaData.getOrders(FieldMetaData.java:1127)
> > > at
> > >
> > >
> >
> org.apache.openjpa.jdbc.meta.strats.StoreCollectionFieldStrategy.selectEager(StoreCollectionFieldStrategy.java:209)
> > > at
> > >
> > >
> >
> org.apache.openjpa.jdbc.meta.strats.StoreCollectionFieldStrategy.selectEagerJoin(StoreCollectionFieldStrategy.java:174)
> > > at
> > >
> > >
> >
> org.apache.openjpa.jdbc.meta.FieldMapping.selectEagerJoin(FieldMapping.java:713)
> > > <snip>
> > >
> > > What's confusing is that I ran into the problem regardless of the
> access
> > > type.
> > >
> > > Lars, if you're seeing the same NPE then I think you can resolve the
> > issue
> > > by creating an Entity for the nickname field, or removing the @OrderBy
> > > annotation.
> > >
> > > If this does resolve the problem and you would like to use the
> @OrderBy
> > > annotation along with @PersistentCollection, please open a JIRA at
> > > http://issues.apache.org/jira/browse/OPENJPA.
> > >
> > > Sorry for the red herring last night and I hope this helps,
> > >
> > > -Mike
> > >
> > >
> > >
> > > On Tue, Apr 15, 2008 at 12:50 AM, Janko Heilgeist <
> > > janko.heilgeist@rzg.mpg.de> wrote:
> > >
> > > > Hi Michael,
> > > >
> > > > Michael Dick wrote:
> > > >
> > > > > If you put the annotations on a get or set method then the JPA
> > > > > provider will expect property access to be used (ie
> > > > > PersonNew.setFirstName("John")).
> > > > >
> > > >
> > > > JPA specification, section 2.1.1:
> > > >
> > > > "[...] When property-based access is used, the object/relational
> > mapping
> > > > annotations for the entity class annotate the getter property
> > > accessors[2].
> > > > [...]
> > > >
> > > > [2] These annotations must not be applied to the setter methods."
> > > >
> > > > In the example below the fields are private which is probably the
> > > > > root problem when you use field access.
> > > > >
> > > >
> > > > JPA specification, section 2.1.1:
> > > >
> > > > "[...] The persistent state of an entity is represented by instance
> > > > variables [...] Instance variables must be private, protected, or
> > > package
> > > > visibility. [...]"
> > > >
> > > > So this should not be the problem. But I can't see anything wrong
> > > either.
> > > > Lars, can you post the stacktrace of your NPE?
> > > >
> > > > Regards, Janko
> > > >
> > > >
> > > >
> > > >
> > > > > Have you tried making the fields public in the Person class you
> > > > > provided?
> > > > >
> > > > > hth, Mike
> > > > >
> > > > >
> > > > >
> > > > > On Mon, Apr 14, 2008 at 2:04 AM, Lars Vogel
> > > > > <la...@googlemail.com> wrote:
> > > > >
> > > > > Hi,
> > > > > >
> > > > > > my understanding so far was that it doesn't matter if I have the
> > > > > > annotation on the instance variable or on the the getter method
> of
> > > > > > the class.
> > > > > >
> > > > > > It that true? Because I have an example where I receive a Null
> > > > > > pointer exception if I put the annotation on the instance
> variable
> > > > > > and not on the getter. Example below. The error occurs during
> the
> > > > > > access of the JobList variable. The whole project is attached in
> > > > > > case someone would like to have a look. For testing just
> exchange
> > > > > > PersonNew.java with Person.java.
> > > > > >
> > > > > > Best regards, Lars
> > > > > >
> > > > > > ----------
> > > > > >
> > > > > > This works: ------------------------------
> > > > > >
> > > > > > package datamodel.impl;
> > > > > >
> > > > > > import java.util.ArrayList; import java.util.List;
> > > > > >
> > > > > > import javax.persistence.Column; import
> javax.persistence.Entity;
> > > > > > import javax.persistence.GeneratedValue; import
> > > > > > javax.persistence.GenerationType; import javax.persistence.Id;
> > > import
> > > > > > javax.persistence.OneToMany; import
> > > > > > javax.persistence.OrderBy; import javax.persistence.Transient;
> > > > > >
> > > > > > import org.apache.openjpa.persistence.PersistentCollection;
> > > > > >
> > > > > > import datamodel.IPerson;
> > > > > >
> > > > > > @Entity public class PersonNew implements IPerson { private
> String
> > > > > > id; private String firstName; private String lastName;
> > > > > >
> > > > > > private String nonsenseField = "";
> > > > > >
> > > > > > private List<Job> jobList = new ArrayList<Job>();
> > > > > >
> > > > > > private List<String> nickNameList = new ArrayList<String>();
> > > > > >
> > > > > > @Id @GeneratedValue(strategy=GenerationType.SEQUENCE) public
> > String
> > > > > > getId() { return id; }
> > > > > >
> > > > > > public void setId(String Id) { this.id = Id; }
> > > > > >
> > > > > >
> > > > > > public String getFirstName() { return firstName; }
> > > > > >
> > > > > > public void setFirstName(String firstName) { this.firstName =
> > > > > > firstName; }
> > > > > >
> > > > > > // Leave the standard column name of the table public String
> > > > > > getLastName() { return lastName; }
> > > > > >
> > > > > > public void setLastName(String lastName) { this.lastName =
> > > > > > lastName; }
> > > > > >
> > > > > > @Transient public String getNonsenseField() { return
> > nonsenseField;
> > > > > > }
> > > > > >
> > > > > > public void setNonsenseField(String nonsenseField) {
> > > > > > this.nonsenseField = nonsenseField; }
> > > > > >
> > > > > > @OneToMany public List<Job> getJobsList() { return this.jobList;
> }
> > > > > >
> > > > > > public void setJobsList(List<Job> nickName) { this.jobList =
> > > > > > nickName; }
> > > > > >
> > > > > > @PersistentCollection @OrderBy public List<String>
> > > > > > getNickNameList() { return nickNameList; }
> > > > > >
> > > > > > public void setNickNameList(List<String> nickNameString) {
> > > > > > this.nickNameList = nickNameString; } }
> > > > > >
> > > > > >
> > > > > > This results in an error:
> > > > > >
> > > > > > package datamodel.impl;
> > > > > >
> > > > > > import java.util.ArrayList; import java.util.List;
> > > > > >
> > > > > > import javax.persistence.Column; import
> javax.persistence.Entity;
> > > > > > import javax.persistence.GeneratedValue; import
> > > > > > javax.persistence.GenerationType; import javax.persistence.Id;
> > > import
> > > > > > javax.persistence.OneToMany; import
> > > > > > javax.persistence.OrderBy; import javax.persistence.Transient;
> > > > > >
> > > > > > import org.apache.openjpa.persistence.PersistentCollection;
> > > > > >
> > > > > > import datamodel.IPerson;
> > > > > >
> > > > > > @Entity public class Person implements IPerson { @Id
> > > > > > @GeneratedValue(strategy=GenerationType.SEQUENCE) private String
> > > > > > id; private String firstName; private String lastName;
> > > > > >
> > > > > > @Transient private String nonsenseField = ""; @OneToMany private
> > > > > > List<Job> jobList = new ArrayList<Job>(); @PersistentCollection
> > > > > > @OrderBy private List<String> nickNameList = new
> > > > > > ArrayList<String>();
> > > > > >
> > > > > >
> > > > > > public String getId() { return id; }
> > > > > >
> > > > > > public void setId(String Id) { this.id = Id; }
> > > > > >
> > > > > >
> > > > > > public String getFirstName() { return firstName; }
> > > > > >
> > > > > > public void setFirstName(String firstName) { this.firstName =
> > > > > > firstName; }
> > > > > >
> > > > > > // Leave the standard column name of the table public String
> > > > > > getLastName() { return lastName; }
> > > > > >
> > > > > > public void setLastName(String lastName) { this.lastName =
> > > > > > lastName; }
> > > > > >
> > > > > > public String getNonsenseField() { return nonsenseField; }
> > > > > >
> > > > > > public void setNonsenseField(String nonsenseField) {
> > > > > > this.nonsenseField = nonsenseField; }
> > > > > >
> > > > > >
> > > > > > public List<Job> getJobsList() { return this.jobList; }
> > > > > >
> > > > > > public void setJobsList(List<Job> nickName) { this.jobList =
> > > > > > nickName; }
> > > > > >
> > > > > >
> > > > > > public List<String> getNickNameList() { return nickNameList; }
> > > > > >
> > > > > > public void setNickNameList(List<String> nickNameString) {
> > > > > > this.nickNameList = nickNameString; } }
> > > > > >
> > > > > >
> > > > >
> > > >
> > >
> >
>
Re: JPAAnnotations on the instance variable or on the getter
Posted by Michael Dick <mi...@gmail.com>.
Hi Lars,
It looks like you aren't hitting the same problem I was.
Are you running the PCEnhancer tool to enhance your entity classes? I've
been able to reproduce the problem on OpenJPA 1.0.2 if the entities aren't
enhanced prior to running the test.
You'll see something like this in the logs if the entities haven't been
enhanced :
1756 people INFO [main] openjpa.Enhance - Creating subclass for "[class
datamodel.impl.Person, class datamodel.impl.Job]". This means that your
application will be less efficient and will consume more memory than it
would if you ran the OpenJPA enhancer. Additionally, lazy loading will not
be available for one-to-one and many-to-one persistent attributes in types
using field access; they will be loaded eagerly instead.
Could you try enhancing the entities and see if that resolves the problem?
The OpenJPA manual covers enhancement at the following location :
http://openjpa.apache.org/docs/latest/manual/manual.html#ref_guide_pc_enhance
-Mike
On Mon, Apr 21, 2008 at 1:21 AM, Lars Vogel <la...@googlemail.com>
wrote:
> Hi Mike,
>
> even if I remove the @OrderBy annotation the error occurs. It seems that
> JPA
> cannot access the content of the list List<Jobs>. Please see my response
> to
> Janko.
>
> Best regards, Lars
>
>
> 2008/4/16, Michael Dick <mi...@gmail.com>:
> >
> > Hi Janko and Lars
> >
> > I'd forgotten about the restriction. When I saw that there was different
> > behavior between property and field access I guessed it was something
> with
> > the access level of his fields - maybe something in the subclassing
> > support.
> >
> >
> > I took a closer look at the example and I think the problem of is that
> it
> > uses a List of Strings as the target of the @OrderBy annotation. The
> > target
> > of the @OrderBy annotation is expected to be an entity which is causing
> a
> > NPE.
> >
> > I'm not sure it was the same NPE that Lars hit though. Here's what I've
> > been
> > seeing (with OpenJPA 1.2.0-SNAPSHOT):
> >
> > java.lang.NullPointerException
> > at
> > org.apache.openjpa.meta.FieldMetaData.getOrders(FieldMetaData.java:1127)
> > at
> >
> >
> org.apache.openjpa.jdbc.meta.strats.StoreCollectionFieldStrategy.selectEager(StoreCollectionFieldStrategy.java:209)
> > at
> >
> >
> org.apache.openjpa.jdbc.meta.strats.StoreCollectionFieldStrategy.selectEagerJoin(StoreCollectionFieldStrategy.java:174)
> > at
> >
> >
> org.apache.openjpa.jdbc.meta.FieldMapping.selectEagerJoin(FieldMapping.java:713)
> > <snip>
> >
> > What's confusing is that I ran into the problem regardless of the access
> > type.
> >
> > Lars, if you're seeing the same NPE then I think you can resolve the
> issue
> > by creating an Entity for the nickname field, or removing the @OrderBy
> > annotation.
> >
> > If this does resolve the problem and you would like to use the @OrderBy
> > annotation along with @PersistentCollection, please open a JIRA at
> > http://issues.apache.org/jira/browse/OPENJPA.
> >
> > Sorry for the red herring last night and I hope this helps,
> >
> > -Mike
> >
> >
> >
> > On Tue, Apr 15, 2008 at 12:50 AM, Janko Heilgeist <
> > janko.heilgeist@rzg.mpg.de> wrote:
> >
> > > Hi Michael,
> > >
> > > Michael Dick wrote:
> > >
> > > > If you put the annotations on a get or set method then the JPA
> > > > provider will expect property access to be used (ie
> > > > PersonNew.setFirstName("John")).
> > > >
> > >
> > > JPA specification, section 2.1.1:
> > >
> > > "[...] When property-based access is used, the object/relational
> mapping
> > > annotations for the entity class annotate the getter property
> > accessors[2].
> > > [...]
> > >
> > > [2] These annotations must not be applied to the setter methods."
> > >
> > > In the example below the fields are private which is probably the
> > > > root problem when you use field access.
> > > >
> > >
> > > JPA specification, section 2.1.1:
> > >
> > > "[...] The persistent state of an entity is represented by instance
> > > variables [...] Instance variables must be private, protected, or
> > package
> > > visibility. [...]"
> > >
> > > So this should not be the problem. But I can't see anything wrong
> > either.
> > > Lars, can you post the stacktrace of your NPE?
> > >
> > > Regards, Janko
> > >
> > >
> > >
> > >
> > > > Have you tried making the fields public in the Person class you
> > > > provided?
> > > >
> > > > hth, Mike
> > > >
> > > >
> > > >
> > > > On Mon, Apr 14, 2008 at 2:04 AM, Lars Vogel
> > > > <la...@googlemail.com> wrote:
> > > >
> > > > Hi,
> > > > >
> > > > > my understanding so far was that it doesn't matter if I have the
> > > > > annotation on the instance variable or on the the getter method of
> > > > > the class.
> > > > >
> > > > > It that true? Because I have an example where I receive a Null
> > > > > pointer exception if I put the annotation on the instance variable
> > > > > and not on the getter. Example below. The error occurs during the
> > > > > access of the JobList variable. The whole project is attached in
> > > > > case someone would like to have a look. For testing just exchange
> > > > > PersonNew.java with Person.java.
> > > > >
> > > > > Best regards, Lars
> > > > >
> > > > > ----------
> > > > >
> > > > > This works: ------------------------------
> > > > >
> > > > > package datamodel.impl;
> > > > >
> > > > > import java.util.ArrayList; import java.util.List;
> > > > >
> > > > > import javax.persistence.Column; import javax.persistence.Entity;
> > > > > import javax.persistence.GeneratedValue; import
> > > > > javax.persistence.GenerationType; import javax.persistence.Id;
> > import
> > > > > javax.persistence.OneToMany; import
> > > > > javax.persistence.OrderBy; import javax.persistence.Transient;
> > > > >
> > > > > import org.apache.openjpa.persistence.PersistentCollection;
> > > > >
> > > > > import datamodel.IPerson;
> > > > >
> > > > > @Entity public class PersonNew implements IPerson { private String
> > > > > id; private String firstName; private String lastName;
> > > > >
> > > > > private String nonsenseField = "";
> > > > >
> > > > > private List<Job> jobList = new ArrayList<Job>();
> > > > >
> > > > > private List<String> nickNameList = new ArrayList<String>();
> > > > >
> > > > > @Id @GeneratedValue(strategy=GenerationType.SEQUENCE) public
> String
> > > > > getId() { return id; }
> > > > >
> > > > > public void setId(String Id) { this.id = Id; }
> > > > >
> > > > >
> > > > > public String getFirstName() { return firstName; }
> > > > >
> > > > > public void setFirstName(String firstName) { this.firstName =
> > > > > firstName; }
> > > > >
> > > > > // Leave the standard column name of the table public String
> > > > > getLastName() { return lastName; }
> > > > >
> > > > > public void setLastName(String lastName) { this.lastName =
> > > > > lastName; }
> > > > >
> > > > > @Transient public String getNonsenseField() { return
> nonsenseField;
> > > > > }
> > > > >
> > > > > public void setNonsenseField(String nonsenseField) {
> > > > > this.nonsenseField = nonsenseField; }
> > > > >
> > > > > @OneToMany public List<Job> getJobsList() { return this.jobList; }
> > > > >
> > > > > public void setJobsList(List<Job> nickName) { this.jobList =
> > > > > nickName; }
> > > > >
> > > > > @PersistentCollection @OrderBy public List<String>
> > > > > getNickNameList() { return nickNameList; }
> > > > >
> > > > > public void setNickNameList(List<String> nickNameString) {
> > > > > this.nickNameList = nickNameString; } }
> > > > >
> > > > >
> > > > > This results in an error:
> > > > >
> > > > > package datamodel.impl;
> > > > >
> > > > > import java.util.ArrayList; import java.util.List;
> > > > >
> > > > > import javax.persistence.Column; import javax.persistence.Entity;
> > > > > import javax.persistence.GeneratedValue; import
> > > > > javax.persistence.GenerationType; import javax.persistence.Id;
> > import
> > > > > javax.persistence.OneToMany; import
> > > > > javax.persistence.OrderBy; import javax.persistence.Transient;
> > > > >
> > > > > import org.apache.openjpa.persistence.PersistentCollection;
> > > > >
> > > > > import datamodel.IPerson;
> > > > >
> > > > > @Entity public class Person implements IPerson { @Id
> > > > > @GeneratedValue(strategy=GenerationType.SEQUENCE) private String
> > > > > id; private String firstName; private String lastName;
> > > > >
> > > > > @Transient private String nonsenseField = ""; @OneToMany private
> > > > > List<Job> jobList = new ArrayList<Job>(); @PersistentCollection
> > > > > @OrderBy private List<String> nickNameList = new
> > > > > ArrayList<String>();
> > > > >
> > > > >
> > > > > public String getId() { return id; }
> > > > >
> > > > > public void setId(String Id) { this.id = Id; }
> > > > >
> > > > >
> > > > > public String getFirstName() { return firstName; }
> > > > >
> > > > > public void setFirstName(String firstName) { this.firstName =
> > > > > firstName; }
> > > > >
> > > > > // Leave the standard column name of the table public String
> > > > > getLastName() { return lastName; }
> > > > >
> > > > > public void setLastName(String lastName) { this.lastName =
> > > > > lastName; }
> > > > >
> > > > > public String getNonsenseField() { return nonsenseField; }
> > > > >
> > > > > public void setNonsenseField(String nonsenseField) {
> > > > > this.nonsenseField = nonsenseField; }
> > > > >
> > > > >
> > > > > public List<Job> getJobsList() { return this.jobList; }
> > > > >
> > > > > public void setJobsList(List<Job> nickName) { this.jobList =
> > > > > nickName; }
> > > > >
> > > > >
> > > > > public List<String> getNickNameList() { return nickNameList; }
> > > > >
> > > > > public void setNickNameList(List<String> nickNameString) {
> > > > > this.nickNameList = nickNameString; } }
> > > > >
> > > > >
> > > >
> > >
> >
>
Re: JPAAnnotations on the instance variable or on the getter
Posted by Lars Vogel <la...@googlemail.com>.
Hi Mike,
even if I remove the @OrderBy annotation the error occurs. It seems that JPA
cannot access the content of the list List<Jobs>. Please see my response to
Janko.
Best regards, Lars
2008/4/16, Michael Dick <mi...@gmail.com>:
>
> Hi Janko and Lars
>
> I'd forgotten about the restriction. When I saw that there was different
> behavior between property and field access I guessed it was something with
> the access level of his fields - maybe something in the subclassing
> support.
>
>
> I took a closer look at the example and I think the problem of is that it
> uses a List of Strings as the target of the @OrderBy annotation. The
> target
> of the @OrderBy annotation is expected to be an entity which is causing a
> NPE.
>
> I'm not sure it was the same NPE that Lars hit though. Here's what I've
> been
> seeing (with OpenJPA 1.2.0-SNAPSHOT):
>
> java.lang.NullPointerException
> at
> org.apache.openjpa.meta.FieldMetaData.getOrders(FieldMetaData.java:1127)
> at
>
> org.apache.openjpa.jdbc.meta.strats.StoreCollectionFieldStrategy.selectEager(StoreCollectionFieldStrategy.java:209)
> at
>
> org.apache.openjpa.jdbc.meta.strats.StoreCollectionFieldStrategy.selectEagerJoin(StoreCollectionFieldStrategy.java:174)
> at
>
> org.apache.openjpa.jdbc.meta.FieldMapping.selectEagerJoin(FieldMapping.java:713)
> <snip>
>
> What's confusing is that I ran into the problem regardless of the access
> type.
>
> Lars, if you're seeing the same NPE then I think you can resolve the issue
> by creating an Entity for the nickname field, or removing the @OrderBy
> annotation.
>
> If this does resolve the problem and you would like to use the @OrderBy
> annotation along with @PersistentCollection, please open a JIRA at
> http://issues.apache.org/jira/browse/OPENJPA.
>
> Sorry for the red herring last night and I hope this helps,
>
> -Mike
>
>
>
> On Tue, Apr 15, 2008 at 12:50 AM, Janko Heilgeist <
> janko.heilgeist@rzg.mpg.de> wrote:
>
> > Hi Michael,
> >
> > Michael Dick wrote:
> >
> > > If you put the annotations on a get or set method then the JPA
> > > provider will expect property access to be used (ie
> > > PersonNew.setFirstName("John")).
> > >
> >
> > JPA specification, section 2.1.1:
> >
> > "[...] When property-based access is used, the object/relational mapping
> > annotations for the entity class annotate the getter property
> accessors[2].
> > [...]
> >
> > [2] These annotations must not be applied to the setter methods."
> >
> > In the example below the fields are private which is probably the
> > > root problem when you use field access.
> > >
> >
> > JPA specification, section 2.1.1:
> >
> > "[...] The persistent state of an entity is represented by instance
> > variables [...] Instance variables must be private, protected, or
> package
> > visibility. [...]"
> >
> > So this should not be the problem. But I can't see anything wrong
> either.
> > Lars, can you post the stacktrace of your NPE?
> >
> > Regards, Janko
> >
> >
> >
> >
> > > Have you tried making the fields public in the Person class you
> > > provided?
> > >
> > > hth, Mike
> > >
> > >
> > >
> > > On Mon, Apr 14, 2008 at 2:04 AM, Lars Vogel
> > > <la...@googlemail.com> wrote:
> > >
> > > Hi,
> > > >
> > > > my understanding so far was that it doesn't matter if I have the
> > > > annotation on the instance variable or on the the getter method of
> > > > the class.
> > > >
> > > > It that true? Because I have an example where I receive a Null
> > > > pointer exception if I put the annotation on the instance variable
> > > > and not on the getter. Example below. The error occurs during the
> > > > access of the JobList variable. The whole project is attached in
> > > > case someone would like to have a look. For testing just exchange
> > > > PersonNew.java with Person.java.
> > > >
> > > > Best regards, Lars
> > > >
> > > > ----------
> > > >
> > > > This works: ------------------------------
> > > >
> > > > package datamodel.impl;
> > > >
> > > > import java.util.ArrayList; import java.util.List;
> > > >
> > > > import javax.persistence.Column; import javax.persistence.Entity;
> > > > import javax.persistence.GeneratedValue; import
> > > > javax.persistence.GenerationType; import javax.persistence.Id;
> import
> > > > javax.persistence.OneToMany; import
> > > > javax.persistence.OrderBy; import javax.persistence.Transient;
> > > >
> > > > import org.apache.openjpa.persistence.PersistentCollection;
> > > >
> > > > import datamodel.IPerson;
> > > >
> > > > @Entity public class PersonNew implements IPerson { private String
> > > > id; private String firstName; private String lastName;
> > > >
> > > > private String nonsenseField = "";
> > > >
> > > > private List<Job> jobList = new ArrayList<Job>();
> > > >
> > > > private List<String> nickNameList = new ArrayList<String>();
> > > >
> > > > @Id @GeneratedValue(strategy=GenerationType.SEQUENCE) public String
> > > > getId() { return id; }
> > > >
> > > > public void setId(String Id) { this.id = Id; }
> > > >
> > > >
> > > > public String getFirstName() { return firstName; }
> > > >
> > > > public void setFirstName(String firstName) { this.firstName =
> > > > firstName; }
> > > >
> > > > // Leave the standard column name of the table public String
> > > > getLastName() { return lastName; }
> > > >
> > > > public void setLastName(String lastName) { this.lastName =
> > > > lastName; }
> > > >
> > > > @Transient public String getNonsenseField() { return nonsenseField;
> > > > }
> > > >
> > > > public void setNonsenseField(String nonsenseField) {
> > > > this.nonsenseField = nonsenseField; }
> > > >
> > > > @OneToMany public List<Job> getJobsList() { return this.jobList; }
> > > >
> > > > public void setJobsList(List<Job> nickName) { this.jobList =
> > > > nickName; }
> > > >
> > > > @PersistentCollection @OrderBy public List<String>
> > > > getNickNameList() { return nickNameList; }
> > > >
> > > > public void setNickNameList(List<String> nickNameString) {
> > > > this.nickNameList = nickNameString; } }
> > > >
> > > >
> > > > This results in an error:
> > > >
> > > > package datamodel.impl;
> > > >
> > > > import java.util.ArrayList; import java.util.List;
> > > >
> > > > import javax.persistence.Column; import javax.persistence.Entity;
> > > > import javax.persistence.GeneratedValue; import
> > > > javax.persistence.GenerationType; import javax.persistence.Id;
> import
> > > > javax.persistence.OneToMany; import
> > > > javax.persistence.OrderBy; import javax.persistence.Transient;
> > > >
> > > > import org.apache.openjpa.persistence.PersistentCollection;
> > > >
> > > > import datamodel.IPerson;
> > > >
> > > > @Entity public class Person implements IPerson { @Id
> > > > @GeneratedValue(strategy=GenerationType.SEQUENCE) private String
> > > > id; private String firstName; private String lastName;
> > > >
> > > > @Transient private String nonsenseField = ""; @OneToMany private
> > > > List<Job> jobList = new ArrayList<Job>(); @PersistentCollection
> > > > @OrderBy private List<String> nickNameList = new
> > > > ArrayList<String>();
> > > >
> > > >
> > > > public String getId() { return id; }
> > > >
> > > > public void setId(String Id) { this.id = Id; }
> > > >
> > > >
> > > > public String getFirstName() { return firstName; }
> > > >
> > > > public void setFirstName(String firstName) { this.firstName =
> > > > firstName; }
> > > >
> > > > // Leave the standard column name of the table public String
> > > > getLastName() { return lastName; }
> > > >
> > > > public void setLastName(String lastName) { this.lastName =
> > > > lastName; }
> > > >
> > > > public String getNonsenseField() { return nonsenseField; }
> > > >
> > > > public void setNonsenseField(String nonsenseField) {
> > > > this.nonsenseField = nonsenseField; }
> > > >
> > > >
> > > > public List<Job> getJobsList() { return this.jobList; }
> > > >
> > > > public void setJobsList(List<Job> nickName) { this.jobList =
> > > > nickName; }
> > > >
> > > >
> > > > public List<String> getNickNameList() { return nickNameList; }
> > > >
> > > > public void setNickNameList(List<String> nickNameString) {
> > > > this.nickNameList = nickNameString; } }
> > > >
> > > >
> > >
> >
>
Re: JPAAnnotations on the instance variable or on the getter
Posted by Michael Dick <mi...@gmail.com>.
Hi Janko and Lars
I'd forgotten about the restriction. When I saw that there was different
behavior between property and field access I guessed it was something with
the access level of his fields - maybe something in the subclassing support.
I took a closer look at the example and I think the problem of is that it
uses a List of Strings as the target of the @OrderBy annotation. The target
of the @OrderBy annotation is expected to be an entity which is causing a
NPE.
I'm not sure it was the same NPE that Lars hit though. Here's what I've been
seeing (with OpenJPA 1.2.0-SNAPSHOT):
java.lang.NullPointerException
at
org.apache.openjpa.meta.FieldMetaData.getOrders(FieldMetaData.java:1127)
at
org.apache.openjpa.jdbc.meta.strats.StoreCollectionFieldStrategy.selectEager(StoreCollectionFieldStrategy.java:209)
at
org.apache.openjpa.jdbc.meta.strats.StoreCollectionFieldStrategy.selectEagerJoin(StoreCollectionFieldStrategy.java:174)
at
org.apache.openjpa.jdbc.meta.FieldMapping.selectEagerJoin(FieldMapping.java:713)
<snip>
What's confusing is that I ran into the problem regardless of the access
type.
Lars, if you're seeing the same NPE then I think you can resolve the issue
by creating an Entity for the nickname field, or removing the @OrderBy
annotation.
If this does resolve the problem and you would like to use the @OrderBy
annotation along with @PersistentCollection, please open a JIRA at
http://issues.apache.org/jira/browse/OPENJPA.
Sorry for the red herring last night and I hope this helps,
-Mike
On Tue, Apr 15, 2008 at 12:50 AM, Janko Heilgeist <
janko.heilgeist@rzg.mpg.de> wrote:
> Hi Michael,
>
> Michael Dick wrote:
>
> > If you put the annotations on a get or set method then the JPA
> > provider will expect property access to be used (ie
> > PersonNew.setFirstName("John")).
> >
>
> JPA specification, section 2.1.1:
>
> "[...] When property-based access is used, the object/relational mapping
> annotations for the entity class annotate the getter property accessors[2].
> [...]
>
> [2] These annotations must not be applied to the setter methods."
>
> In the example below the fields are private which is probably the
> > root problem when you use field access.
> >
>
> JPA specification, section 2.1.1:
>
> "[...] The persistent state of an entity is represented by instance
> variables [...] Instance variables must be private, protected, or package
> visibility. [...]"
>
> So this should not be the problem. But I can't see anything wrong either.
> Lars, can you post the stacktrace of your NPE?
>
> Regards, Janko
>
>
>
>
> > Have you tried making the fields public in the Person class you
> > provided?
> >
> > hth, Mike
> >
> >
> >
> > On Mon, Apr 14, 2008 at 2:04 AM, Lars Vogel
> > <la...@googlemail.com> wrote:
> >
> > Hi,
> > >
> > > my understanding so far was that it doesn't matter if I have the
> > > annotation on the instance variable or on the the getter method of
> > > the class.
> > >
> > > It that true? Because I have an example where I receive a Null
> > > pointer exception if I put the annotation on the instance variable
> > > and not on the getter. Example below. The error occurs during the
> > > access of the JobList variable. The whole project is attached in
> > > case someone would like to have a look. For testing just exchange
> > > PersonNew.java with Person.java.
> > >
> > > Best regards, Lars
> > >
> > > ----------
> > >
> > > This works: ------------------------------
> > >
> > > package datamodel.impl;
> > >
> > > import java.util.ArrayList; import java.util.List;
> > >
> > > import javax.persistence.Column; import javax.persistence.Entity;
> > > import javax.persistence.GeneratedValue; import
> > > javax.persistence.GenerationType; import javax.persistence.Id; import
> > > javax.persistence.OneToMany; import
> > > javax.persistence.OrderBy; import javax.persistence.Transient;
> > >
> > > import org.apache.openjpa.persistence.PersistentCollection;
> > >
> > > import datamodel.IPerson;
> > >
> > > @Entity public class PersonNew implements IPerson { private String
> > > id; private String firstName; private String lastName;
> > >
> > > private String nonsenseField = "";
> > >
> > > private List<Job> jobList = new ArrayList<Job>();
> > >
> > > private List<String> nickNameList = new ArrayList<String>();
> > >
> > > @Id @GeneratedValue(strategy=GenerationType.SEQUENCE) public String
> > > getId() { return id; }
> > >
> > > public void setId(String Id) { this.id = Id; }
> > >
> > >
> > > public String getFirstName() { return firstName; }
> > >
> > > public void setFirstName(String firstName) { this.firstName =
> > > firstName; }
> > >
> > > // Leave the standard column name of the table public String
> > > getLastName() { return lastName; }
> > >
> > > public void setLastName(String lastName) { this.lastName =
> > > lastName; }
> > >
> > > @Transient public String getNonsenseField() { return nonsenseField;
> > > }
> > >
> > > public void setNonsenseField(String nonsenseField) {
> > > this.nonsenseField = nonsenseField; }
> > >
> > > @OneToMany public List<Job> getJobsList() { return this.jobList; }
> > >
> > > public void setJobsList(List<Job> nickName) { this.jobList =
> > > nickName; }
> > >
> > > @PersistentCollection @OrderBy public List<String>
> > > getNickNameList() { return nickNameList; }
> > >
> > > public void setNickNameList(List<String> nickNameString) {
> > > this.nickNameList = nickNameString; } }
> > >
> > >
> > > This results in an error:
> > >
> > > package datamodel.impl;
> > >
> > > import java.util.ArrayList; import java.util.List;
> > >
> > > import javax.persistence.Column; import javax.persistence.Entity;
> > > import javax.persistence.GeneratedValue; import
> > > javax.persistence.GenerationType; import javax.persistence.Id; import
> > > javax.persistence.OneToMany; import
> > > javax.persistence.OrderBy; import javax.persistence.Transient;
> > >
> > > import org.apache.openjpa.persistence.PersistentCollection;
> > >
> > > import datamodel.IPerson;
> > >
> > > @Entity public class Person implements IPerson { @Id
> > > @GeneratedValue(strategy=GenerationType.SEQUENCE) private String
> > > id; private String firstName; private String lastName;
> > >
> > > @Transient private String nonsenseField = ""; @OneToMany private
> > > List<Job> jobList = new ArrayList<Job>(); @PersistentCollection
> > > @OrderBy private List<String> nickNameList = new
> > > ArrayList<String>();
> > >
> > >
> > > public String getId() { return id; }
> > >
> > > public void setId(String Id) { this.id = Id; }
> > >
> > >
> > > public String getFirstName() { return firstName; }
> > >
> > > public void setFirstName(String firstName) { this.firstName =
> > > firstName; }
> > >
> > > // Leave the standard column name of the table public String
> > > getLastName() { return lastName; }
> > >
> > > public void setLastName(String lastName) { this.lastName =
> > > lastName; }
> > >
> > > public String getNonsenseField() { return nonsenseField; }
> > >
> > > public void setNonsenseField(String nonsenseField) {
> > > this.nonsenseField = nonsenseField; }
> > >
> > >
> > > public List<Job> getJobsList() { return this.jobList; }
> > >
> > > public void setJobsList(List<Job> nickName) { this.jobList =
> > > nickName; }
> > >
> > >
> > > public List<String> getNickNameList() { return nickNameList; }
> > >
> > > public void setNickNameList(List<String> nickNameString) {
> > > this.nickNameList = nickNameString; } }
> > >
> > >
> >
>
Re: JPAAnnotations on the instance variable or on the getter
Posted by Lars Vogel <la...@googlemail.com>.
Hi Janko,
the sytem gives me a NPE if I try to access the collection for Jobs.
Exception in thread "main" java.lang.NullPointerException
at main.Main.main(Main.java:77)
This part is where my test code tries to access the list of jobs (indicated
via // This is line 77) In my example this works if the annotation is on the
getter. The complete coding is in my first posting.
Best regards, Lars
------
// Go through each of the entities and print out each of their
// messages, as well as the date on which it was created
for (Person m : (List<Person>) q.getResultList()) {
System.out.println("Say hello to " + m.getFirstName() + " "
+ m.getLastName());
// Job will always be filled in this example
IJob2 job = m.getJobList().get(0); // This is line 77
System.out.println("He earns " + job.getSalery()
+ " in his job as " + job.getJobDescr());
// Lets printout the family he belongs to
System.out.println("Family " +m.getFamily().getDescription());
// Same here, nickname will in this example always be filled.
System.out.println("His nickname is " +
m.getNickNameList().get(0));
}
2008/4/15, Janko Heilgeist <ja...@rzg.mpg.de>:
>
> Hi Michael,
>
> Michael Dick wrote:
>
> > If you put the annotations on a get or set method then the JPA
> > provider will expect property access to be used (ie
> > PersonNew.setFirstName("John")).
> >
>
> JPA specification, section 2.1.1:
>
> "[...] When property-based access is used, the object/relational mapping
> annotations for the entity class annotate the getter property accessors[2].
> [...]
>
> [2] These annotations must not be applied to the setter methods."
>
> In the example below the fields are private which is probably the
> > root problem when you use field access.
> >
>
> JPA specification, section 2.1.1:
>
> "[...] The persistent state of an entity is represented by instance
> variables [...] Instance variables must be private, protected, or package
> visibility. [...]"
>
> So this should not be the problem. But I can't see anything wrong either.
> Lars, can you post the stacktrace of your NPE?
>
> Regards, Janko
>
>
>
> > Have you tried making the fields public in the Person class you
> > provided?
> >
> > hth, Mike
> >
> >
> >
> > On Mon, Apr 14, 2008 at 2:04 AM, Lars Vogel
> > <la...@googlemail.com> wrote:
> >
> > Hi,
> > >
> > > my understanding so far was that it doesn't matter if I have the
> > > annotation on the instance variable or on the the getter method of
> > > the class.
> > >
> > > It that true? Because I have an example where I receive a Null
> > > pointer exception if I put the annotation on the instance variable
> > > and not on the getter. Example below. The error occurs during the
> > > access of the JobList variable. The whole project is attached in
> > > case someone would like to have a look. For testing just exchange
> > > PersonNew.java with Person.java.
> > >
> > > Best regards, Lars
> > >
> > > ----------
> > >
> > > This works: ------------------------------
> > >
> > > package datamodel.impl;
> > >
> > > import java.util.ArrayList; import java.util.List;
> > >
> > > import javax.persistence.Column; import javax.persistence.Entity;
> > > import javax.persistence.GeneratedValue; import
> > > javax.persistence.GenerationType; import javax.persistence.Id; import
> > > javax.persistence.OneToMany; import
> > > javax.persistence.OrderBy; import javax.persistence.Transient;
> > >
> > > import org.apache.openjpa.persistence.PersistentCollection;
> > >
> > > import datamodel.IPerson;
> > >
> > > @Entity public class PersonNew implements IPerson { private String
> > > id; private String firstName; private String lastName;
> > >
> > > private String nonsenseField = "";
> > >
> > > private List<Job> jobList = new ArrayList<Job>();
> > >
> > > private List<String> nickNameList = new ArrayList<String>();
> > >
> > > @Id @GeneratedValue(strategy=GenerationType.SEQUENCE) public String
> > > getId() { return id; }
> > >
> > > public void setId(String Id) { this.id = Id; }
> > >
> > >
> > > public String getFirstName() { return firstName; }
> > >
> > > public void setFirstName(String firstName) { this.firstName =
> > > firstName; }
> > >
> > > // Leave the standard column name of the table public String
> > > getLastName() { return lastName; }
> > >
> > > public void setLastName(String lastName) { this.lastName =
> > > lastName; }
> > >
> > > @Transient public String getNonsenseField() { return nonsenseField;
> > > }
> > >
> > > public void setNonsenseField(String nonsenseField) {
> > > this.nonsenseField = nonsenseField; }
> > >
> > > @OneToMany public List<Job> getJobsList() { return this.jobList; }
> > >
> > > public void setJobsList(List<Job> nickName) { this.jobList =
> > > nickName; }
> > >
> > > @PersistentCollection @OrderBy public List<String>
> > > getNickNameList() { return nickNameList; }
> > >
> > > public void setNickNameList(List<String> nickNameString) {
> > > this.nickNameList = nickNameString; } }
> > >
> > >
> > > This results in an error:
> > >
> > > package datamodel.impl;
> > >
> > > import java.util.ArrayList; import java.util.List;
> > >
> > > import javax.persistence.Column; import javax.persistence.Entity;
> > > import javax.persistence.GeneratedValue; import
> > > javax.persistence.GenerationType; import javax.persistence.Id; import
> > > javax.persistence.OneToMany; import
> > > javax.persistence.OrderBy; import javax.persistence.Transient;
> > >
> > > import org.apache.openjpa.persistence.PersistentCollection;
> > >
> > > import datamodel.IPerson;
> > >
> > > @Entity public class Person implements IPerson { @Id
> > > @GeneratedValue(strategy=GenerationType.SEQUENCE) private String
> > > id; private String firstName; private String lastName;
> > >
> > > @Transient private String nonsenseField = ""; @OneToMany private
> > > List<Job> jobList = new ArrayList<Job>(); @PersistentCollection
> > > @OrderBy private List<String> nickNameList = new
> > > ArrayList<String>();
> > >
> > >
> > > public String getId() { return id; }
> > >
> > > public void setId(String Id) { this.id = Id; }
> > >
> > >
> > > public String getFirstName() { return firstName; }
> > >
> > > public void setFirstName(String firstName) { this.firstName =
> > > firstName; }
> > >
> > > // Leave the standard column name of the table public String
> > > getLastName() { return lastName; }
> > >
> > > public void setLastName(String lastName) { this.lastName =
> > > lastName; }
> > >
> > > public String getNonsenseField() { return nonsenseField; }
> > >
> > > public void setNonsenseField(String nonsenseField) {
> > > this.nonsenseField = nonsenseField; }
> > >
> > >
> > > public List<Job> getJobsList() { return this.jobList; }
> > >
> > > public void setJobsList(List<Job> nickName) { this.jobList =
> > > nickName; }
> > >
> > >
> > > public List<String> getNickNameList() { return nickNameList; }
> > >
> > > public void setNickNameList(List<String> nickNameString) {
> > > this.nickNameList = nickNameString; } }
> > >
> > >
> >
>
Re: JPAAnnotations on the instance variable or on the getter
Posted by Janko Heilgeist <ja...@rzg.mpg.de>.
Hi Michael,
Michael Dick wrote:
> If you put the annotations on a get or set method then the JPA
> provider will expect property access to be used (ie
> PersonNew.setFirstName("John")).
JPA specification, section 2.1.1:
"[...] When property-based access is used, the object/relational mapping
annotations for the entity class annotate the getter property
accessors[2]. [...]
[2] These annotations must not be applied to the setter methods."
> In the example below the fields are private which is probably the
> root problem when you use field access.
JPA specification, section 2.1.1:
"[...] The persistent state of an entity is represented by instance
variables [...] Instance variables must be private, protected, or
package visibility. [...]"
So this should not be the problem. But I can't see anything wrong
either. Lars, can you post the stacktrace of your NPE?
Regards, Janko
>
> Have you tried making the fields public in the Person class you
> provided?
>
> hth, Mike
>
>
>
> On Mon, Apr 14, 2008 at 2:04 AM, Lars Vogel
> <la...@googlemail.com> wrote:
>
>> Hi,
>>
>> my understanding so far was that it doesn't matter if I have the
>> annotation on the instance variable or on the the getter method of
>> the class.
>>
>> It that true? Because I have an example where I receive a Null
>> pointer exception if I put the annotation on the instance variable
>> and not on the getter. Example below. The error occurs during the
>> access of the JobList variable. The whole project is attached in
>> case someone would like to have a look. For testing just exchange
>> PersonNew.java with Person.java.
>>
>> Best regards, Lars
>>
>> ----------
>>
>> This works: ------------------------------
>>
>> package datamodel.impl;
>>
>> import java.util.ArrayList; import java.util.List;
>>
>> import javax.persistence.Column; import javax.persistence.Entity;
>> import javax.persistence.GeneratedValue; import
>> javax.persistence.GenerationType; import javax.persistence.Id;
>> import javax.persistence.OneToMany; import
>> javax.persistence.OrderBy; import javax.persistence.Transient;
>>
>> import org.apache.openjpa.persistence.PersistentCollection;
>>
>> import datamodel.IPerson;
>>
>> @Entity public class PersonNew implements IPerson { private String
>> id; private String firstName; private String lastName;
>>
>> private String nonsenseField = "";
>>
>> private List<Job> jobList = new ArrayList<Job>();
>>
>> private List<String> nickNameList = new ArrayList<String>();
>>
>> @Id @GeneratedValue(strategy=GenerationType.SEQUENCE) public String
>> getId() { return id; }
>>
>> public void setId(String Id) { this.id = Id; }
>>
>>
>> public String getFirstName() { return firstName; }
>>
>> public void setFirstName(String firstName) { this.firstName =
>> firstName; }
>>
>> // Leave the standard column name of the table public String
>> getLastName() { return lastName; }
>>
>> public void setLastName(String lastName) { this.lastName =
>> lastName; }
>>
>> @Transient public String getNonsenseField() { return nonsenseField;
>> }
>>
>> public void setNonsenseField(String nonsenseField) {
>> this.nonsenseField = nonsenseField; }
>>
>> @OneToMany public List<Job> getJobsList() { return this.jobList; }
>>
>> public void setJobsList(List<Job> nickName) { this.jobList =
>> nickName; }
>>
>> @PersistentCollection @OrderBy public List<String>
>> getNickNameList() { return nickNameList; }
>>
>> public void setNickNameList(List<String> nickNameString) {
>> this.nickNameList = nickNameString; } }
>>
>>
>> This results in an error:
>>
>> package datamodel.impl;
>>
>> import java.util.ArrayList; import java.util.List;
>>
>> import javax.persistence.Column; import javax.persistence.Entity;
>> import javax.persistence.GeneratedValue; import
>> javax.persistence.GenerationType; import javax.persistence.Id;
>> import javax.persistence.OneToMany; import
>> javax.persistence.OrderBy; import javax.persistence.Transient;
>>
>> import org.apache.openjpa.persistence.PersistentCollection;
>>
>> import datamodel.IPerson;
>>
>> @Entity public class Person implements IPerson { @Id
>> @GeneratedValue(strategy=GenerationType.SEQUENCE) private String
>> id; private String firstName; private String lastName;
>>
>> @Transient private String nonsenseField = ""; @OneToMany private
>> List<Job> jobList = new ArrayList<Job>(); @PersistentCollection
>> @OrderBy private List<String> nickNameList = new
>> ArrayList<String>();
>>
>>
>> public String getId() { return id; }
>>
>> public void setId(String Id) { this.id = Id; }
>>
>>
>> public String getFirstName() { return firstName; }
>>
>> public void setFirstName(String firstName) { this.firstName =
>> firstName; }
>>
>> // Leave the standard column name of the table public String
>> getLastName() { return lastName; }
>>
>> public void setLastName(String lastName) { this.lastName =
>> lastName; }
>>
>> public String getNonsenseField() { return nonsenseField; }
>>
>> public void setNonsenseField(String nonsenseField) {
>> this.nonsenseField = nonsenseField; }
>>
>>
>> public List<Job> getJobsList() { return this.jobList; }
>>
>> public void setJobsList(List<Job> nickName) { this.jobList =
>> nickName; }
>>
>>
>> public List<String> getNickNameList() { return nickNameList; }
>>
>> public void setNickNameList(List<String> nickNameString) {
>> this.nickNameList = nickNameString; } }
>>
>
Re: JPAAnnotations on the instance variable or on the getter
Posted by Michael Dick <mi...@gmail.com>.
Hi Lars,
Where you put the annotations indicates whether you want to use property or
field based access. If you put the annotations on a get or set method then
the JPA provider will expect property access to be used (ie
PersonNew.setFirstName("John")). If the annotations are on the field then a
JPA provider can expect the fields to be accessed directly (ie
Person.firstName="John"))
In the example below the fields are private which is probably the root
problem when you use field access.
Have you tried making the fields public in the Person class you provided?
hth,
Mike
On Mon, Apr 14, 2008 at 2:04 AM, Lars Vogel <la...@googlemail.com>
wrote:
> Hi,
>
> my understanding so far was that it doesn't matter if I have the
> annotation on the instance variable or on the the getter method of the
> class.
>
> It that true? Because I have an example where I receive a Null pointer
> exception if I put the annotation on the instance variable and not on the
> getter. Example below. The error occurs during the access of the JobList
> variable. The whole project is attached in case someone would like to have a
> look. For testing just exchange PersonNew.java with Person.java.
>
> Best regards, Lars
>
> ----------
>
> This works:
> ------------------------------
>
> package datamodel.impl;
>
> import java.util.ArrayList;
> import java.util.List;
>
> import javax.persistence.Column;
> import javax.persistence.Entity;
> import javax.persistence.GeneratedValue;
> import javax.persistence.GenerationType;
> import javax.persistence.Id;
> import javax.persistence.OneToMany;
> import javax.persistence.OrderBy;
> import javax.persistence.Transient;
>
> import org.apache.openjpa.persistence.PersistentCollection;
>
> import datamodel.IPerson;
>
> @Entity
> public class PersonNew implements IPerson {
> private String id;
> private String firstName;
> private String lastName;
>
> private String nonsenseField = "";
>
> private List<Job> jobList = new ArrayList<Job>();
>
> private List<String> nickNameList = new ArrayList<String>();
>
> @Id
> @GeneratedValue(strategy=GenerationType.SEQUENCE)
> public String getId() {
> return id;
> }
>
> public void setId(String Id) {
> this.id = Id;
> }
>
>
> public String getFirstName() {
> return firstName;
> }
>
> public void setFirstName(String firstName) {
> this.firstName = firstName;
> }
>
> // Leave the standard column name of the table
> public String getLastName() {
> return lastName;
> }
>
> public void setLastName(String lastName) {
> this.lastName = lastName;
> }
>
> @Transient
> public String getNonsenseField() {
> return nonsenseField;
> }
>
> public void setNonsenseField(String nonsenseField) {
> this.nonsenseField = nonsenseField;
> }
>
> @OneToMany
> public List<Job> getJobsList() {
> return this.jobList;
> }
>
> public void setJobsList(List<Job> nickName) {
> this.jobList = nickName;
> }
>
> @PersistentCollection
> @OrderBy
> public List<String> getNickNameList() {
> return nickNameList;
> }
>
> public void setNickNameList(List<String> nickNameString) {
> this.nickNameList = nickNameString;
> }
> }
>
>
> This results in an error:
>
> package datamodel.impl;
>
> import java.util.ArrayList;
> import java.util.List;
>
> import javax.persistence.Column;
> import javax.persistence.Entity;
> import javax.persistence.GeneratedValue;
> import javax.persistence.GenerationType;
> import javax.persistence.Id;
> import javax.persistence.OneToMany;
> import javax.persistence.OrderBy;
> import javax.persistence.Transient;
>
> import org.apache.openjpa.persistence.PersistentCollection;
>
> import datamodel.IPerson;
>
> @Entity
> public class Person implements IPerson {
> @Id
> @GeneratedValue(strategy=GenerationType.SEQUENCE)
> private String id;
> private String firstName;
> private String lastName;
>
> @Transient
> private String nonsenseField = "";
> @OneToMany
> private List<Job> jobList = new ArrayList<Job>();
> @PersistentCollection
> @OrderBy
> private List<String> nickNameList = new ArrayList<String>();
>
>
> public String getId() {
> return id;
> }
>
> public void setId(String Id) {
> this.id = Id;
> }
>
>
> public String getFirstName() {
> return firstName;
> }
>
> public void setFirstName(String firstName) {
> this.firstName = firstName;
> }
>
> // Leave the standard column name of the table
> public String getLastName() {
> return lastName;
> }
>
> public void setLastName(String lastName) {
> this.lastName = lastName;
> }
>
> public String getNonsenseField() {
> return nonsenseField;
> }
>
> public void setNonsenseField(String nonsenseField) {
> this.nonsenseField = nonsenseField;
> }
>
>
> public List<Job> getJobsList() {
> return this.jobList;
> }
>
> public void setJobsList(List<Job> nickName) {
> this.jobList = nickName;
> }
>
>
> public List<String> getNickNameList() {
> return nickNameList;
> }
>
> public void setNickNameList(List<String> nickNameString) {
> this.nickNameList = nickNameString;
> }
> }
>