Re: FW: How to set null for a column for which the corresponding java type is long

[ZZZ Liu <z2...@yahoo.com>]

Thanks a lot for all of your answers. I just realized
that OJB can convert from JDBC types to Number
(Integer, Long, BigInteger,BigDecimal) automatically.
For example, JDBC type BIGINT can be converted to
either primitive long or Object Long without any
FieldConversion. In this case, I can just use Long
instead of long to solve the problem. 

Just wondering anybody can update the document
http://db.apache.org/ojb/jdbc-types.html to make that
explicit?

Thanks,
Zhe

> 
> 
> -----Original Message-----
> From: Martin Kal�n [mailto:martin.kalen@curalia.se]
> Sent: Wednesday, January 28, 2004 1:04 AM
> To: OJB Users List
> Subject: Re: How to set null for a column for which
> the corresponding
> java type is long
> 
> 
> Danilo Tommasina wrote:
> 
> >> I have a data base column. The data type is
> number
> >> (10). It is nullable. The JDBC type defined in
> >> repository is BIGINT and the corresponding java
> type
> >> is long (default). Can anybody tell me how to
> save a
> >> record so that the value of that column is null
> >> instead of zero?
> >
> > Do not use a primitive data type in your
> persistent class, use instead a
> >  subtype of Number. (Integer, Long, BigInteger,
> BigDecimal,... )
> 
> Or; if you don't have control over the bean or want
> to keep long, use a
> field conversion class that converts long values of
> 0 as NULL.
> 
> There are quite a few pre-packaged field conversion
> classes that come
> with OJB, they can be found in the package:
> org.apache.ojb.broker.accesslayer.conversions
> 
> The Int2IntegerFieldConversion class can be used as
> a template for how
> to write a field conversion for a long with
> 0-inserts as NULL.
> 
> See
>
http://cvs.apache.org/viewcvs.cgi/*checkout*/db-ojb/src/java/org/apache/ojb/
>
broker/accesslayer/conversions/Int2IntegerFieldConversion.java?content-type=
> text%2Fplain&rev=1.3
> 
> 
> To use field conversions, specify them in your
> repository. Eg:
> 
> <class-descriptor class="{x}" table="{x}">
>   <field-descriptor name="{x}" column="{x}"
> jdbc-type="{x}"
>    
>
conversion="com.mycompany.PrimitiveLong2LongFieldConversion"/>
> 
> 
> HTH,
>   Martin
> 
> --
> Martin Kal�n
> Curalia AB              Web:  http://www.curalia.se
> Orrspelsv�gen 2B        Mail: info@curalia.se
> SE-182 79  Stocksund    Tel:  +46-8-410 064 40
> 
> 
>
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