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skoptelov
 Post subject: HQL and RTTI
PostPosted: Fri Sep 17, 2004 9:36 am 
Newbie

Joined: Thu Aug 05, 2004 1:54 am
Posts: 10
Location: Novosibirsk, Russia
Hibernate version:
2.1.6 ( MySQL DB )
Mapping documents:
Code:

    <class name="com.fis.om.Task" discriminator-value="20">
        <id column="id" name="id">
            <generator class="native" />
        </id>

        <discriminator column="discriminator" type="byte" />

        <property name="completionDate">
            <column name="completionDate" sql-type="DATETIME" />
        </property>
        <property name="approvalDate">
            <column name="approvalDate" sql-type="DATETIME" />
        </property>
        <property name="name">
            <column name="name" sql-type="VARCHAR( 100 ) COLLATE utf8_general_ci" />
        </property>
        <property name="description">
            <column name="description" sql-type="TEXT COLLATE utf8_general_ci" />
        </property>
        <property name="type" type="com.fis.om.TaskType" />

        <many-to-one name="company" class="com.fis.om.Company" />
        <many-to-one name="originator" class="com.fis.om.Employee" />
        <many-to-one name="owner" class="com.fis.om.Employee" />

        <set name="history"
             lazy="true"
             order-by="creationDate desc"
             cascade="delete"
        >
            <key column="task" />
            <one-to-many class="com.fis.om.TaskHistory" />
        </set>

        <subclass name="com.fis.om.PointTask" discriminator-value="21">
            <property name="assignedDate">
                <column name="assignedDate" sql-type="DATE" />
            </property>
            <property name="assignedTime">
                <column name="assignedTime" sql-type="TIME" />
            </property>
        </subclass>

        <subclass name="com.fis.om.SliceTask" discriminator-value="22">
            <many-to-one name="slice" class="com.fis.om.TimeSlice" />
        </subclass>

    </class>


How can I do something like instanceof and dynamic casts in HQL? I need a query like

Code:
            "FROM Task AS t" +
            " WHERE" +
                " IF(" +
                    " t instanceof SliceTask," +
                    " ( ( SliceTask )t ).slice.date >= :start," +
                    " ( ( PointTask )t ).assignedDate >= :start" +
                " )" +
            " ORDER BY" +
                " t.completionDate IS NULL ASC"
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david
 Post subject:
PostPosted: Fri Sep 17, 2004 10:41 pm 
Hibernate Team
Hibernate Team

Joined: Tue Aug 26, 2003 7:19 pm
Posts: 2364
Location: Brisbane, Australia
No - HQL is Hibernates SQL with object focus and extensions.
You can build the query string using Java.
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skoptelov
 Post subject:
PostPosted: Sat Sep 18, 2004 12:52 am 
Newbie

Joined: Thu Aug 05, 2004 1:54 am
Posts: 10
Location: Novosibirsk, Russia
I don't want to build query in some special way. I want the query to return me instances of subclasses which are ordered by field that is subclass-dependent. If I have the instance of SliceTask I want the order column contain task.slice.date field and if it's PointTask, I want it to contain task.assignedDate field.
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david
 Post subject:
PostPosted: Sun Sep 19, 2004 8:35 pm 
Hibernate Team
Hibernate Team

Joined: Tue Aug 26, 2003 7:19 pm
Posts: 2364
Location: Brisbane, Australia
But you are - its just a matter of where you place your conditional.

You want to do it in HQL you will have to place the logic in a form that builds the query string appropriately. Otherwise, move it into your database's stored procedure and call it using JDBC from the connection collected from the session.
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skoptelov
 Post subject: Solved
PostPosted: Sun Sep 19, 2004 10:54 pm 
Newbie

Joined: Thu Aug 05, 2004 1:54 am
Posts: 10
Location: Novosibirsk, Russia
The problem is solved. I just wrote SQL for tasks retrieval, where I

1) Left join Slice to Task

2) Check for discriminator value

3) Put proper column in ORDER BY clause according to discriminator.

And then createSqlQuery() and it works.
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david
 Post subject:
PostPosted: Mon Sep 20, 2004 7:46 pm 
Hibernate Team
Hibernate Team

Joined: Tue Aug 26, 2003 7:19 pm
Posts: 2364
Location: Brisbane, Australia
Cool.
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