Re: relationship between inherited entities

From: sabiha (sdilovi..ahoo.com)
Date: Fri Apr 16 2004 - 15:41:31 EDT

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    Hi Andrus,

     

    Thanks for your help. I had success with this relationship. I did exactly what you suggested me to do and it works.

     

    I added an extra attribute �is_manager� (relevant only for �developer� that it can be aware of corresponding �manager�) to �Employee� DbEntity and its value is �employee_id� of corresponding �manager�.

    And I created 2 DbRelationhips for �Employee� DbEntity: 1st is �employees�, to-many relationship, with *target* �Employee�, and joined with *source* �employee_id�, *target* �is_manager�.

    2nd is �toManager�, with *target* �Employee�, and joined with *source* �is_manager�, *target* �employee_id�.

    And then I created ObjRelationship in �Manager� that maps to �employees� DbRelationship.

     

    Thanks

    Sabiha

     

    Andrus Adamchik <andru..bjectstyle.org> wrote:
    Hi Sabiha,

    > if I want to have relationship (to-many) between �Manager� and
    > �Developer�, how to implement it?

    Actually I haven't tested such case yet, but I don't see why it
    wouldn't work... To map such relationship, create a corresponding
    self-referencing pair of DbRelationships in Employee *DbEntity*, for
    instance called "employees" and "toManager". Then create a new
    ObjRelationship in Manager ObjEntity (but not in Employee ObjEntity)
    that maps to "employees" DbRelationship.

    Let us know how this worked.

    > Did I miss something here or did something wrong?

    You also need to do some "magic" with your data objects per chapter
    8.6.1 buried deep in the user guide:
    http://objectstyle.org/cayenne/userguide/dataobjects/dataobjects-
    inheritance.html . This step is probably just a temporary thing.
    Hopefully in the next releases we will move this information it to the
    mapping.

    Cheers
    Andrus

                    
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