Data type for multi-select combo

Support
#1

For saving the selected values in a multi-select combo what is the data structure/field recommended?

#2

Usually it’s a many-to-many collection property.

For example:

Hobby.java

@JmixEntity
@Entity
public class Hobby {
// ...
}

User.java

@JmixEntity
@Entity
public class User {
// ...
    @JoinTable(name = "USER_HOBBY_LINK",
            joinColumns = @JoinColumn(name = "USER_ID", referencedColumnName = "ID"),
            inverseJoinColumns = @JoinColumn(name = "HOBBY_ID", referencedColumnName = "ID"))
    @ManyToMany
    private List<Hobby> hobbies;
}

user-detail-view.xml

<data>
  <instance id="userDc"
            class="com.company.untitled2.entity.User">
      <fetchPlan extends="_base">
          <property name="hobbies" fetchPlan="_base"/>
      </fetchPlan>
      <loader/>
  </instance>
  <collection id="hobbiesDc" class="com.company.untitled2.entity.Hobby">
      <fetchPlan   extends="_base"/>
      <loader id="hobbiesDl" readOnly="true">
          <query>
              <![CDATA[select e from Hobby e]]>
          </query>
      </loader>
  </collection>
</data>
<layout>
  <formLayout id="form" dataContainer="userDc">
      <!-- ... -->
      <multiSelectComboBox property="hobbies" itemsContainer="hobbiesDc"/>
  </formLayout>
#3

Thank you Konstantin.
Can this be used for one-to-may collection property too?

#4

Yes, it will link the selected entities to the master one (User in the example above) by setting the reference to the master.
But I struggle to imagine a use case for this scenario. Do you have any idea?