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我在重用记录来填充交叉引用表时遇到问题。Hibernate 尝试更新外键记录而不是填充交叉引用表。

插入新记录工作正常。

数据库图 在此处输入图像描述

当我添加新位置并将它们链接到交叉引用表中时，它可以正常工作：

//Get specific object
TestContainer tc = (TestContainer) session.createQuery("from TestContainer where id = :id")
        .setParameter("id", id).list().get(0);

//Locations
Set<TestContainerLocation> tcl = new HashSet<TestContainerLocation>();

TestContainerLocation loc1 = new TestContainerLocation();
loc1.setLocationName("String1"); 
TestContainerLocation loc2 = new TestContainerLocation();
loc2.setLocationName("String2");

tcl.add(loc1);
tcl.add(loc2);

tc.setTestContainerLocation(tcl);

session.saveOrUpdate(tc);

当我尝试重用现有位置时，它不会通过。它不是插入交叉引用表，而是尝试通过提供空值来更新外键表，但由于约束而失败。

//Get specific object
TestContainer tc = (TestContainer) session.createQuery("from TestContainer where id = :id")
        .setParameter("id", id).list().get(0);

Set<TestContainerLocation> tcl = new HashSet<TestContainerLocation>();

TestContainerLocation loc1 = new TestContainerLocation();
loc1.setLocationId(1);//existing Id 
TestContainerLocation loc2 = new TestContainerLocation();
loc2.setLocationId(2);//existing Id

tcl.add(loc1);
tcl.add(loc2);

tc.setTestContainerLocation(tcl);

session.saveOrUpdate(tc);

错误：

Hibernate: select testcontai0_.id as id0_, testcontai0_.step_one as step2_0_, testcontai0_.step_two as step3_0_, testcontai0_.step_three as step4_0_, testcontai0_.type_id as type5_0_ from test_container testcontai0_ where testcontai0_.id=?
Hibernate: update test_container_location set location_name=? where location_id=?
Hibernate: update test_container_location set location_name=? where location_id=?
org.hibernate.exception.ConstraintViolationException: Could not execute JDBC batch update
...
Caused by: java.sql.BatchUpdateException: Column 'location_name' cannot be null

映射

测试容器.hbm.xml

<class name="TestContainer"
    table="test_container">
    <id name="id" column="id" type="long" unsaved-value="null">
        <generator class="identity"></generator>
    </id>

    <property name="stepOne" type="string" length="255" column="step_one" not-null="false" />
    <property name="stepTwo" type="integer" column="step_two" not-null="false" />
    <property name="stepThree" type="string" length="255" column="step_three" not-null="false" />

    <many-to-one name="testContainerType" class="org.test.data.TestContainerType" fetch="select">
        <column name="type_id" not-null="true"/>
    </many-to-one>

    <set name="testContainerLocation" table="test_container_location_lookup"
     inverse="false" lazy="true" fetch="select" cascade="all">
        <key>
            <column name="id" not-null="true"/>
        </key>
        <many-to-many entity-name="org.test.data.TestContainerLocation">
            <column name="location_id" not-null="true" />
        </many-to-many>
    </set>

</class>

测试容器位置.hbm.xml

    <class name="TestContainerLocation"
        table="test_container_location">
        <id name="locationId" column="location_id" type="integer" unsaved-value="null">
            <generator class="identity"></generator>
        </id>
        <property name="locationName" type="string" length="255" column="location_name" not-null="false" />

        <set name="testContainer" table="test_container_location_lookup"
         inverse="true" lazy="true" fetch="select" cascade="all">
            <key>
                <column name="location_id" not-null="true"/>
            </key>
            <many-to-many entity-name="org.test.data.TestContainer">
                <column name="id" not-null="true" />
            </many-to-many>
        </set>
    </class>
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2 回答 2

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Use session.get() or load() instead of new TestContainerLocation(). For example:

TestContainerLocation loc1 = (TestContainerLocation) session.load(TestContainerLocation.class, 1);

EDIT: Hibernate tries to update the TestContainerLocation entity when you use new() and then set the id.

于 2013-06-10T18:09:29.497 回答
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此错误由您的默认字符串大小字符
引起您有两种选择来解决此问题
1.您必须增加字符串字符大小
示例

<property name="companyname" column="company_name" length='25' />

您的公司名称大小必须小于 25
2. 将类型更改为文本示例

<property name="companyname" column="company_name" type='text' />
于 2013-12-03T22:30:58.700 回答