CODEWITHSUNDEEP
javaspringhibernatehibernate-mapping
Sri
Sri

Reputation: 1505

foreign key must have same number of columns as the reference primary key hibernate - many to many

I have domain Classes - User, Role, Group, Group Role

User Domain

private long id, 
private String userName, 
private String password, 
Set<Role> roles = new HashSet<Role>();

User.hbm.xml

<hibernate-mapping package="uk.co.jmr.sdp.domain">
<class name="User" table="user">
        <id name="id" unsaved-value="-1">
            <generator class="native"/>
        </id>
        <property name="userName" column="user_name"/>
        <property name="password" column="password"/>
        <property name="emailId" column="email_id"/>

        <set name="roles" table="user_role" lazy="false" cascade="all">
            <key column="user_id"/>
            <many-to-many column="role_id" class="Role" fetch="join"/>
        </set>

        <set name="groupRoles" table="user_grouprole" lazy="false" cascade="all">
            <key column="user_id"/>
            <many-to-many column="group_role_id" class="GroupRole" fetch="join"/>
        </set> 

</class>
</hibernate-mapping>

I have user_grouprole table as a join table for an User and Set of grouproles I have user_role table as a join table for an user and set of roles

Group Domain

private long id;
private String groupName;
private Set<Role> roles = new HashSet<Role>();

Group.hbm.xml

<hibernate-mapping package="uk.co.jmr.sdp.domain">
 <class name="Group" table="group">
 <id name="id" unsaved-value="-1">
        <generator class="native"/>
 </id>
 <property name="groupName" column="group_name"></property>

 <set name="roles" table="group_role" lazy="false" cascade="all">
        <key column="group_id"/>
        <many-to-many column="role_id" class="Role" fetch="join"/>
    </set>

GroupRole

private long id;
private Role role;
private Group group;

GroupRole.hbm.xml

<class name="GroupRole" table="group_role">
    <id name="id" unsaved-value="-1">
            <generator class="native"/>
    </id>
    <many-to-one name="role" class="uk.co.jmr.sdp.domain.Role"
            column="role_id" lazy="false" not-null="true" />

    <many-to-one name="group" class="uk.co.jmr.sdp.domain.Group"
            column="group_id" lazy="false" not-null="true" /> 

 </class>
</hibernate-mapping>

When I try to test with a main class, I get a mapping error like a hibernate mapping error like Foreign key (FK5110401A8398947:user_grouprole [group_role_id])) must have same number of columns as the referenced primary key (group_role [group_id,role_id])

What is this error? Why I get this error? What should I do to rectify this error??? Any Solutions ? Can anyone explain what is this error?

Thanks in Advance

Upvotes: 2

Views: 20169

Answers (1)

Thiago Uriel Garcia
Thiago Uriel Garcia

Reputation: 142

Your error is telling that your table USER contains a foreign key on a column named GROUP_ROLE_ID, but your referenced table, GROUP_ROLE, defines it's primary key with two columns ROLE_ID and GROUP_ID, which by the way is very common for relationship tables.

Seems to me that the only reason that you are mapping GroupRole is because you need it in your User entity. Well, if your domain model is really correct, then you need to think about how you want to synchronize your User's FK and GroupRole's PK. For that you might:

  1. Create a PK object for your composite key or define your ID's correctly in your mappings;
  2. Change your PK definition in GroupRole table.

Best regards.

Upvotes: 3

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