EclipseLink/UserGuide/JPA/Basic JPA Development/Mapping/Relationship Mappings/Common Relationship Configurations/JoinFetch

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Key API

• @JoinFetch

@JoinFetch

Use the @JoinFetch annotation to enable the joining and reading of the related objects in the same query as the source object.

Note: We recommend setting join fetching at the query level, as not all queries require joining.

You can specify the @JoinFetch annotation for the following mappings:

• @OneToOne
• @OneToMany
• @ManyToOne
• @ManyToMany
• @BasicCollection (deprecated)
• @BasicMap (deprecated)

Alternatively, you can use batch reading, especially for collection relationships.]].

@JoinFetch Annotation Attributes

Attribute	Description	Default	Required?
value	Set this attribute to the org.eclipse.persistence.annotations.JoinFetchType enumerated type of the fetch that you will be using. The following are the valid values for the JoinFetchType: INNER – This option provides the inner join fetching of the related object. Note: Inner joining does not allow for null or empty values. OUTER – This option provides the outer join fetching of the related object. Note: Outer joining allows for null or empty values.	JoinFetchType.INNER	No

The following example shows how to use the @JoinFetch annotation to specify Employee field managedEmployees.

Example: @JoinFetch Annotation

 @Entity
 public class Employee implements Serializable {
     ...
     @OneToMany(cascade=ALL, mappedBy="owner")
     @JoinFetch(value=OUTER)
     public Collection<Employee> getManagedEmployees() {
         return managedEmployees;
     }
     ...
 }

Version: 2.2.0 DRAFT
Other versions...

Common Relationship Configurations	Common Relationship Configurations	Collection Mappings
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