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From Elias Torres <el...@torrez.us>
Subject Re: How to map multiple properties to same column as writable in jpa
Date Fri, 27 Jul 2007 12:34:33 GMT
I was wondering the same thing (but with JPA of course). I tried and was
getting a message that the members were out of sync.

@ManyToOne(fetch=FetchType.LAZY)
@JoinColumn(name="userid", referencedColumnName="id")
private User user;

and

@Column(name="userid")
private String userId;

How would I go about keeping them in sync? Especially, when someone
calls setUser(user) with a new instance that might not have an id.

Is there a way in OpenJPA to say that the userId column is only for
read-only and not persist operations?

Thanks.

-Elias

Patrick Linskey wrote:
> Hi,
> 
> This forum is for the OpenJPA product, so we don't have much
> experience with Toplink.
> 
> However, from an OpenJPA standpoint, you can map the same column to
> multiple fields without a problem, as long as you don't attempt to set
> the fields to different values during the same transaction.
> 
> -Patrick
> 
> On 7/26/07, saravanan_tvm <skumar_rect2000@yahoo.com> wrote:
>> Hi,
>> I am using toplink from oracle to support JPA.
>> I have the following requirement...
>> i have to map same column for multiple properties using @joincolumn
>> annotation.. eg its something like this
>>
>> @joincolumn(name="PARENT_RECORD_ID")
>> private Drug drug
>>
>> @joincolumn(name="PARENT_RECORD_ID")
>> private Reaction reaction
>>
>> PARENT_RECORD_ID is nothing but primary key of parent table.
>> but while accessing the application i am getting the following exception....
>>
>>  MULTIPLE_WRITE_MAPPINGS_FOR_FIELD
>>
>> Cause: Multiple writable mappings for the field fieldName are defined in the
>> descriptor. Exactly one must be defined as writable; the others must be
>> specified as read-only. When multiple write mappings are defined for the
>> field, TopLink is unable to choose the appropriate mapping for writing the
>> value of the field in the database row. Therefore, the exception is raised
>> during the validation process of descriptors.
>>
>> Action: Make one of those mappings read-only
>>
>> But i cannot make read only, if i make read only then while inserting new
>> records it will be problem
>>
>> please can anyone provide the solution for this...
>> Regards,
>> Saravanan.
>>
>> --
>> View this message in context: http://www.nabble.com/How-to-map-multiple-properties-to-same-column-as-writable-in-jpa-tf4155235.html#a11822480
>> Sent from the OpenJPA Developers mailing list archive at Nabble.com.
>>
>>
> 
> 

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