Question

Got classical Hibernate problem:

Caused by: org.hibernate.MappingException: Repeated column in mapping for entity: entry.Authority column: username (should be mapped with insert="false" update="false")

users.hbm.xml:

<class name="entry.User" table="users">
    <property name="username" column="username"/>
    <set name="authorities" table="authorities" lazy="false" cascade="all">
        <key column="username" not-null="true"/>
        <one-to-many class="entry.Authority"/>
    </set>

authorities.hbm.xml:

    <class name="entry.Authority" table="authorities">
        <id name="id"/>
        <property name="username" column="username"/>
    </class>

Tried classical solution:

<property name="username" column="username"  insert="false" update="false"/>

Got:

java.sql.BatchUpdateException: Field 'username' doesn't have a default value

Why I can’t specify username twice in .xml?
As I understand this declaration <property name="username" column="username"/> relates to User and <key column="username" not-null="true"/> relates to Authorities
.So why they clash?
How can it be fixed with minimum invasion?

EDITED:

    <class name="entry.User" table="users">
        <id name="id">
            <generator class="increment" />
        </id>
        <property name="username" column="username"/>     
        <set name="authorities" table="authorities" lazy="false" cascade="all" inverse="true">
            <key column="username" not-null="true"/>
            <one-to-many class="entry.Authority"/>
        </set>
...

and

<class name="entry.Authority" table="authorities">
    <id name="id"/>
    <property name="username" column="username"/>
    <property name="authority" column="authority"/>
    <many-to-one name="user" class="entry.User">
             <column name="username"/>
     </many-to-one>
</class>

Answer 1

With the key definition in users.hbm.xml <key column="username" not-null="true"/> you already handle the column username in Authorities. The line <property name="username" column="username"/> in authorities.hbm.xml is superfluous, even if used in many-to-one. Every time you load/update or insert the instances of Authorities via Users, the field is handled automatically by Hibernate. If you define the field also in authorities.hbm.xml then it is set twice – that’s why you got your error message.

If you by some special reasons really want to have the username also in authorities.hbm.xml, then you have to specify insert/update = false (as you already did) and a default value to avoid your error message (even if the default never is used). For example

<property name="username" insert="false" update="false">
  <column="username" default="anyValue"/>
</property>

But I would simply recommend this:

<class name="entry.Authority" table="authorities">
  <id name="id"/>
  <property name="authority" column="authority"/>
  <many-to-one name="user" class="entry.User">
         <column name="username"/>
   </many-to-one>
</class>

---

Added after your comment:

Now I see a problem in your new mapping: the <key> element has to reference to the key of the parent table, and that is not the case. The key in the Users table is id, but you use a normal property Username as the foreign key in Authority. There are two possibilities to resolve this:

1) You make Username the key of Users (drop column id and define the key in Users as

<id name="username">
 <column="username"/>
</id>

(I’m not sure if in this case in new instances of Authority hibernate will set the member username automatically or if you have to do it manually.)

new: Here is the complete mapping (not tested):

<class name="entry.User" table="users">
  <id name="username" type="String">
    <column="username"/>
  </id>
  <property name="password" column="password" type="String"/>
  <property name="enabled" column="enabled" type="boolean"/>

  <set name="authorities" table="authorities" lazy="false" cascade="all" inverse="true">
    <key column="username" not-null="true"/>
    <one-to-many class="entry.Authority"/>
  </set>
</class>

2) You make id the foreign key in Authority:
In users.hbm.xml

<key column="id" not-null="true"/>

, and in authority.hbm.xml you replace the column username with

<property name="userId" column="userId"/>

You also have to modify the database table then.