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Posted to users@tomcat.apache.org by Alexander Hartner <al...@j2anywhere.com> on 2008/10/19 22:04:49 UTC

Using Convert to handle NULL values for empty Strings "" 

After having had the problem with null values not being returned as  
nulls and reading some suggestion solution I added a converter to my  
application.

...
   <converter>
     <converter-id>NullStringConverter</converter-id>
     <converter-for-class>java.lang.String</converter-for-class>
     <converter- 
class>com.j2anywhere.addressbookserver.web.NullStringConverter</ 
converter-class>
   </converter>
...


I then implemented it as follows:

...
   public String getAsString(FacesContext context, UIComponent  
component, Object object)
   {
     System.out.println("Converting to String : "+object);

     if (object == null)
     {
       System.out.println("READING null");
       return "NULL";
     }
     else
     {
       if (((String)object).equals(""))
       {
         System.out.println("READING null (Second Check)");
         return null;
       }
       else
       {
         return object.toString();
       }
     }
   }

   public Object getAsObject(FacesContext context, UIComponent  
component, String value)
   {
     System.out.println("Converting to Object: "+value 
+"-"+value.trim().length());
     if (value.trim().length()==0 || value.equals("NULL"))
     {
       System.out.println("WRITING null");
       return null;
     }
     else
     {
       return value.toUpperCase();
     }
   }
...


I can see that it is converting my values, however the object to which  
the inputText fields are bound are still set to empty strings ""

<h:inputText size="50"  
value="#{addressBookController.contactDetails.information}"  
converter="NullStringConverter"/>


Also when reading the object values any nulls are already converted to  
empty strings before ariving at the converter. It seems that there is  
a default converter handling string values.

How can I resolve this problem as set nulls when the input value is an  
empty string other then checking every string in my class  
individually. I would really hate to pollute my object model with  
empty string tests.

Thanks in advance

Re: Using Convert to handle NULL values for empty Strings ""

Posted by Mark Thomas <ma...@apache.org>.
Alexander Hartner wrote:
> Setting the COERCE_TO_ZERO to false in 6.0.18 did the trick for me.

Just a word of warning. Setting COERCE_TO_ZERO to false is not spec
compliant. If you switch containers then you may see different behaviour.

Mark

> Initially I only tested this on 6.0.16.
> 
> Thanks Chuck.
> On 20 Oct 2008, at 00:12, Alexander Hartner wrote:
> 
>> Hi Chuck,
>>
>> Thanks for coming back to me to quickly. I have tried this, but this
>> only seems to work for numbers. I am looking at Strings.
>>
>> So far I have tested this with Sun's JSF 1.2_04-b20-p03 as well as
>> 1.2_09-b02-FCS and myfaces-core-1.2.4.
>>
>> MyFaces gave me some other errors, but now behaves in exactly the same
>> way at Sun implementation, converting any nulls returned by the
>> converter into an empty string.
>>
>> I am hoping that there is a simple solution for this as I surely can't
>> be the first one to pick this up.
>>
>> Thanks for all your support.
>> Alex
>>
>>
>> On 19 Oct 2008, at 23:41, Caldarale, Charles R wrote:
>>
>>>> From: Alexander Hartner [mailto:alex@j2anywhere.com]
>>>> Subject: Re: Using Convert to handle NULL values for empty Strings ""
>>>>
>>>> The problem indeed does not appear in 6.0.14, however both
>>>> 6.0.16 and 18 are affected by it.
>>>>
>>>> I wonder what has changed, and how I can fix this
>>>
>>> This might be related:
>>> https://issues.apache.org/bugzilla/show_bug.cgi?id=43285
>>>
>>> Try playing with the associated COERCE_TO_ZERO system property to see
>>> if it has an effect:
>>> http://tomcat.apache.org/tomcat-6.0-doc/config/systemprops.html#Expression%20Language
>>>
>>>
>>> - Chuck
>>>
>>>
>>> THIS COMMUNICATION MAY CONTAIN CONFIDENTIAL AND/OR OTHERWISE
>>> PROPRIETARY MATERIAL and is thus for use only by the intended
>>> recipient. If you received this in error, please contact the sender
>>> and delete the e-mail and its attachments from all computers.
>>>
>>> ---------------------------------------------------------------------
>>> To start a new topic, e-mail: users@tomcat.apache.org
>>> To unsubscribe, e-mail: users-unsubscribe@tomcat.apache.org
>>> For additional commands, e-mail: users-help@tomcat.apache.org
>>>
>>
> 
> 
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> 
> 



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Re: Using Convert to handle NULL values for empty Strings ""

Posted by Alexander Hartner <al...@j2anywhere.com>.
Setting the COERCE_TO_ZERO to false in 6.0.18 did the trick for me.  
Initially I only tested this on 6.0.16.

Thanks Chuck.
On 20 Oct 2008, at 00:12, Alexander Hartner wrote:

> Hi Chuck,
>
> Thanks for coming back to me to quickly. I have tried this, but this  
> only seems to work for numbers. I am looking at Strings.
>
> So far I have tested this with Sun's JSF 1.2_04-b20-p03 as well as  
> 1.2_09-b02-FCS and myfaces-core-1.2.4.
>
> MyFaces gave me some other errors, but now behaves in exactly the  
> same way at Sun implementation, converting any nulls returned by the  
> converter into an empty string.
>
> I am hoping that there is a simple solution for this as I surely  
> can't be the first one to pick this up.
>
> Thanks for all your support.
> Alex
>
>
> On 19 Oct 2008, at 23:41, Caldarale, Charles R wrote:
>
>>> From: Alexander Hartner [mailto:alex@j2anywhere.com]
>>> Subject: Re: Using Convert to handle NULL values for empty Strings  
>>> ""
>>>
>>> The problem indeed does not appear in 6.0.14, however both
>>> 6.0.16 and 18 are affected by it.
>>>
>>> I wonder what has changed, and how I can fix this
>>
>> This might be related:
>> https://issues.apache.org/bugzilla/show_bug.cgi?id=43285
>>
>> Try playing with the associated COERCE_TO_ZERO system property to  
>> see if it has an effect:
>> http://tomcat.apache.org/tomcat-6.0-doc/config/systemprops.html#Expression%20Language
>>
>> - Chuck
>>
>>
>> THIS COMMUNICATION MAY CONTAIN CONFIDENTIAL AND/OR OTHERWISE  
>> PROPRIETARY MATERIAL and is thus for use only by the intended  
>> recipient. If you received this in error, please contact the sender  
>> and delete the e-mail and its attachments from all computers.
>>
>> ---------------------------------------------------------------------
>> To start a new topic, e-mail: users@tomcat.apache.org
>> To unsubscribe, e-mail: users-unsubscribe@tomcat.apache.org
>> For additional commands, e-mail: users-help@tomcat.apache.org
>>
>


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Re: Using Convert to handle NULL values for empty Strings ""

Posted by Alexander Hartner <al...@j2anywhere.com>.
Hi Chuck,

Thanks for coming back to me to quickly. I have tried this, but this  
only seems to work for numbers. I am looking at Strings.

So far I have tested this with Sun's JSF 1.2_04-b20-p03 as well as  
1.2_09-b02-FCS and myfaces-core-1.2.4.

MyFaces gave me some other errors, but now behaves in exactly the same  
way at Sun implementation, converting any nulls returned by the  
converter into an empty string.

I am hoping that there is a simple solution for this as I surely can't  
be the first one to pick this up.

Thanks for all your support.
Alex


On 19 Oct 2008, at 23:41, Caldarale, Charles R wrote:

>> From: Alexander Hartner [mailto:alex@j2anywhere.com]
>> Subject: Re: Using Convert to handle NULL values for empty Strings ""
>>
>> The problem indeed does not appear in 6.0.14, however both
>> 6.0.16 and 18 are affected by it.
>>
>> I wonder what has changed, and how I can fix this
>
> This might be related:
> https://issues.apache.org/bugzilla/show_bug.cgi?id=43285
>
> Try playing with the associated COERCE_TO_ZERO system property to  
> see if it has an effect:
> http://tomcat.apache.org/tomcat-6.0-doc/config/systemprops.html#Expression%20Language
>
> - Chuck
>
>
> THIS COMMUNICATION MAY CONTAIN CONFIDENTIAL AND/OR OTHERWISE  
> PROPRIETARY MATERIAL and is thus for use only by the intended  
> recipient. If you received this in error, please contact the sender  
> and delete the e-mail and its attachments from all computers.
>
> ---------------------------------------------------------------------
> To start a new topic, e-mail: users@tomcat.apache.org
> To unsubscribe, e-mail: users-unsubscribe@tomcat.apache.org
> For additional commands, e-mail: users-help@tomcat.apache.org
>

RE: Using Convert to handle NULL values for empty Strings ""

Posted by "Caldarale, Charles R" <Ch...@unisys.com>.
> From: Alexander Hartner [mailto:alex@j2anywhere.com]
> Subject: Re: Using Convert to handle NULL values for empty Strings ""
>
> The problem indeed does not appear in 6.0.14, however both
> 6.0.16 and 18 are affected by it.
>
> I wonder what has changed, and how I can fix this

This might be related:
https://issues.apache.org/bugzilla/show_bug.cgi?id=43285

Try playing with the associated COERCE_TO_ZERO system property to see if it has an effect:
http://tomcat.apache.org/tomcat-6.0-doc/config/systemprops.html#Expression%20Language

 - Chuck


THIS COMMUNICATION MAY CONTAIN CONFIDENTIAL AND/OR OTHERWISE PROPRIETARY MATERIAL and is thus for use only by the intended recipient. If you received this in error, please contact the sender and delete the e-mail and its attachments from all computers.

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Re: Using Convert to handle NULL values for empty Strings ""

Posted by Alexander Hartner <al...@j2anywhere.com>.
This problems seems to be related to the version of tomcat being used:

I came accross this post online :

http://forums.sun.com/thread.jspa?forumID=427&threadID=5273588

and then tried 6.0.18 and 6.0.14. Previously I was using 6.0.16. The  
problem indeed does not appear in 6.0.14, however both 6.0.16 and 18  
are affected by it.

I found some other posts on this issue as well :

http://www.icefaces.org/JForum/posts/list/8024.page and https://issues.apache.org/jira/browse/MYFACES-1979

I wonder what has changed, and how I can fix this
Alex

On 19 Oct 2008, at 21:04, Alexander Hartner wrote:

> After having had the problem with null values not being returned as  
> nulls and reading some suggestion solution I added a converter to my  
> application.
>
> ...
>  <converter>
>    <converter-id>NullStringConverter</converter-id>
>    <converter-for-class>java.lang.String</converter-for-class>
>    <converter- 
> class>com.j2anywhere.addressbookserver.web.NullStringConverter</ 
> converter-class>
>  </converter>
> ...
>
>
> I then implemented it as follows:
>
> ...
>  public String getAsString(FacesContext context, UIComponent  
> component, Object object)
>  {
>    System.out.println("Converting to String : "+object);
>
>    if (object == null)
>    {
>      System.out.println("READING null");
>      return "NULL";
>    }
>    else
>    {
>      if (((String)object).equals(""))
>      {
>        System.out.println("READING null (Second Check)");
>        return null;
>      }
>      else
>      {
>        return object.toString();
>      }
>    }
>  }
>
>  public Object getAsObject(FacesContext context, UIComponent  
> component, String value)
>  {
>    System.out.println("Converting to Object: "+value 
> +"-"+value.trim().length());
>    if (value.trim().length()==0 || value.equals("NULL"))
>    {
>      System.out.println("WRITING null");
>      return null;
>    }
>    else
>    {
>      return value.toUpperCase();
>    }
>  }
> ...
>
>
> I can see that it is converting my values, however the object to  
> which the inputText fields are bound are still set to empty strings ""
>
> <h:inputText size="50"  
> value="#{addressBookController.contactDetails.information}"  
> converter="NullStringConverter"/>
>
>
> Also when reading the object values any nulls are already converted  
> to empty strings before ariving at the converter. It seems that  
> there is a default converter handling string values.
>
> How can I resolve this problem as set nulls when the input value is  
> an empty string other then checking every string in my class  
> individually. I would really hate to pollute my object model with  
> empty string tests.
>
> Thanks in advance


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