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teknokrat
 Post subject: Two classes mapped to same table confuse bidirectionality
PostPosted: Tue Feb 03, 2004 7:35 am 
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Joined: Thu Aug 28, 2003 10:54 am
Posts: 67
I have two classes QuoteRequest and CallingListItem mapped to the same table quote_requests. The componenets making up the two classes are different of course but they both have a one-to-many mapping to another class Quote. Now, quote has a many-to-one mapping to QuoteRequest.

when i execute from QuoteRequest I get a luist of quote request objects as expected but when I execute from CallingListItem I get a WrongClassException with the message " Object with id 1234 was not of the specified class quoteRequest"

Is this a bug or are my mappings wrong? Is it ok to have more than one class mapped to the same table or am I doing something that hibernate does not allow?

thanks
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kantorn
 Post subject: Mappings
PostPosted: Tue Feb 03, 2004 7:54 am 
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Joined: Wed Nov 26, 2003 6:22 am
Posts: 76
Location: Stockholm
Hi!

Could you provide us with the mapping files involved?

Sincerely,

/F
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teknokrat
 Post subject:
PostPosted: Tue Feb 03, 2004 8:07 am 
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Joined: Thu Aug 28, 2003 10:54 am
Posts: 67
The QuoteRequest mapping is

Code:

<hibernate-mapping>

    <class name="com.lab.model.quote.QuoteRequest" table="quote_requests">
   
        <id name="id">
            <generator class="sequence">
                <param name="sequence">quote_requests_id_seq</param>
            </generator>
        </id>
       
       <many-to-one name="customer" column="cust_id" outer-join="true" not-null="true" update="false"/>
   
         <property name="product" column="product_type" update="false"/>
      <property name="benefit" column="benefit_type" update="false"/>
      <property name="waiver" column="waiver_basis" update="false"/>
        <property name="sumAssured" column="sum_assured" update="false"/>
        <property name="term" update="false"/>
        <property name="rates" update="false"/>
      <property name="indexLinked" type="boolean" column="index_linked" update="false"/>      
      <property name="specialOffer" type="boolean" column="special_offer" update="false"/>
       
        <component name="error" class="com.lab.common.QuoteError">
           <property name="code" column="error_code"/>
           <property name="message" column="error"/>
        </component>

      <many-to-one name="selectedQuote" column="selected_quote_id" class="com.lab.model.quote.Quote" cascade="delete" outer-join="true"/>


    </class>

</hibernate-mapping>



The CallingListItem mapping is

Code:

    <class name="com.lab.model.CallingListItem" table="quote_requests" polymorphism="explicit">

        <id name="id" column="id">
            <generator class="assigned"/>
        </id>
       
        <many-to-one name="customer" class="com.lab.model.customer.CustomerListItem" column="cust_id"/>

          <property name="lastStatusChangeTime" type="timestamp" column="last_status_change_time"/>
        <property name="lastStatusCheckTime" type="timestamp" column="last_status_check_time"/>
       
      <many-to-one name="quote" class="com.lab.model.quote.Quote" column="selected_quote_id"/>
      
    </class>


and the mapping for Quote is

Code:
   <class name="com.lab.model.quote.Quote" table="quotes">
   
       <cache usage="nonstrict-read-write"/>

        <id name="id">
            <generator class="sequence">
                <param name="sequence">quotes_id_seq</param>
            </generator>
        </id>
       
         <many-to-one name="quoteRequest" class="com.lab.model.quote.QuoteRequest" column="request_id" not-null="true" />

        <many-to-one name="provider" column="provider_id"  not-null="true" update="false"/>

        <property name="premium" update="false"/>
        <property name="rates" update="false"/>
        <property name="sumAssured" column="sum_assured" update="false"/>
        <property name="commissionPcRetained" column="commission_pc_retained" update="false"/>
        <property name="realCommission" column="real_commission" update="false"/>
        <property name="approxCommission" column="approx_commission" update="false"/>

        <property name="note" column="notes" update="false"/>
        <property name="error" column="errors" update="false"/>

     
    </class>
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michael
 Post subject:
PostPosted: Tue Feb 03, 2004 8:21 am 
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Joined: Tue Sep 09, 2003 2:10 pm
Posts: 3246
Location: Passau, Germany
It is not intended to keep two objects which map to the same database row in the session at the same time.
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teknokrat
 Post subject:
PostPosted: Tue Feb 03, 2004 8:23 am 
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Joined: Thu Aug 28, 2003 10:54 am
Posts: 67
If I made CallingListItem inherit from QuoteRequest would this solve the problem? Is there a better way to do this.

thnak you
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michael
 Post subject:
PostPosted: Tue Feb 03, 2004 8:25 am 
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Joined: Tue Sep 09, 2003 2:10 pm
Posts: 3246
Location: Passau, Germany
I suppose no, it is just not supported to associate multiple objects refering to the same row with one session, no matter how you map them.
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kantorn
 Post subject: I'm far from sure
PostPosted: Tue Feb 03, 2004 8:45 am 
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Joined: Wed Nov 26, 2003 6:22 am
Posts: 76
Location: Stockholm
I'm a confused newbie myself, but...

From what I can see you have a <many-to-one> mapping from Quote to QuoteRequest AND a <many-to-one> from QuoteRequest to Quote. What do yo mean by that? Shouldn't you map it as a <many-to-many>?
If you stay with the parent-child model I suggest a good look in the Hibernate2 Reference Documentation 2.1.1, especially chapter 6 and 9.
Pages 49-50 might be especially interesting.

Sincerely,

/F
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teknokrat
 Post subject:
PostPosted: Tue Feb 03, 2004 9:14 am 
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Joined: Thu Aug 28, 2003 10:54 am
Posts: 67
The many-to-one from QuoteRequest to Quote because every quote request has one and only one selected quote. The many-to-one from Quote to QuoteRequest is for bidirectionality, we often need to get the quote request object from the selected quote.

I am not sure what a many-to-many would acomplish as I am not dealing with any collections here. In fact the mapping between selectedQuote and QuoteRequest is one-to-one but we had problems implementing it that way back in hibernate 1.2 and we have not had the time try agin using hibernate 2.1.

My problem is that I need to reference a property of the quotes table from my CallingListItem class but I cannot use the Quote class because it references QuoteRequest which mapped to the same table as CallingListItem. Looks like I will have to create another quote-like class that I can use with calling list item.
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gavin
 Post subject:
PostPosted: Tue Feb 03, 2004 1:48 pm 
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Joined: Tue Aug 26, 2003 12:50 pm
Posts: 5130
Location: Melbourne, Australia
It is not possible (well, at least not without a custom persister) to have two objects representing the same row in the session simultaneously. This is not an unreasonable restriction, I think.
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