Difference between revisions of "EclipseLink/UserGuide/JPA/Basic JPA Development/Mapping/Basic Mappings/Transient"

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(Example: @Transient Annotation)
 
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By default, EclipseLink persistence provider assumes that all the fields of an entity are persistent.
 
By default, EclipseLink persistence provider assumes that all the fields of an entity are persistent.
  
Use the <tt>@Transient</tt> annotation to specify a field or property of an entity that is not persistent (for example, a field or property that is used at run time, but that is not part of the entity's state).
+
Use the <tt>@Transient</tt> annotation or <code><nowiki><transient></nowiki></code> XML to specify a field or property of an entity that is not persistent (for example, a field or property that is used at run time, but that is not part of the entity's state).
  
 
EclipseLink persistence provider will not persist (or create database schema) for a property or field annotated with <tt>@Transient</tt>.
 
EclipseLink persistence provider will not persist (or create database schema) for a property or field annotated with <tt>@Transient</tt>.
  
This annotation can be used with <tt>@Entity</tt>, [[#@MappedSuperclass|<tt>@MappedSuperclass</tt>]]), and [[#@Embeddable|<tt>@Embeddable</tt>]].
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This annotation can be used with <tt>@Entity</tt>, <tt>@MappedSuperclass</tt>, and <tt>@Embeddable</tt>.
 
{{EclipseLink_Spec
 
{{EclipseLink_Spec
 
|section=Section 8.1 "Entity"}}
 
|section=Section 8.1 "Entity"}}
  
 
The <tt>@Transient</tt> annotation does not have attributes.
 
The <tt>@Transient</tt> annotation does not have attributes.
 +
 +
If a field is marked as Java <code>transient</code> it will also be ignored.
  
 
The following example shows how to use the <tt>@Transient</tt> annotation to specify <tt>Employee</tt> field <tt>currentSession</tt> as not persistent. EclipseLink persistence provider will not persist this field.
 
The following example shows how to use the <tt>@Transient</tt> annotation to specify <tt>Employee</tt> field <tt>currentSession</tt> as not persistent. EclipseLink persistence provider will not persist this field.
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======'' Example: @Transient Annotation''======
 
======'' Example: @Transient Annotation''======
 
<source lang="java">
 
<source lang="java">
@Entity
+
@Entity
public class Employee implements Serializable {
+
public class Employee implements Serializable {
    ...
+
    @Id
    @Id
+
    int id;
    int id;
+
 
+
    @Transient
    @Transient
+
    Session currentSession;
    Session currentSession;
+
    ...
    ...
+
}
}
+
</source>
 +
 
 +
======''Example: Using <code><nowiki><transient></nowiki></code> XML''======
 +
<source lang="xml">
 +
<entity class="Employee">
 +
    <attributes>
 +
        <id name="id"/>
 +
        <transient name="currentSession"/>
 +
        ...
 +
    </attributes>
 +
</entity>
 
</source>
 
</source>
  

Latest revision as of 15:16, 27 October 2011

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[edit] @Transient

By default, EclipseLink persistence provider assumes that all the fields of an entity are persistent.

Use the @Transient annotation or <transient> XML to specify a field or property of an entity that is not persistent (for example, a field or property that is used at run time, but that is not part of the entity's state).

EclipseLink persistence provider will not persist (or create database schema) for a property or field annotated with @Transient.

This annotation can be used with @Entity, @MappedSuperclass, and @Embeddable.

Elug javaspec icon.gif

For more information, see Section 8.1 "Entity" in the JPA Specification.

The @Transient annotation does not have attributes.

If a field is marked as Java transient it will also be ignored.

The following example shows how to use the @Transient annotation to specify Employee field currentSession as not persistent. EclipseLink persistence provider will not persist this field.

[edit] Example: @Transient Annotation
@Entity
public class Employee implements Serializable {
    @Id
    int id;
 
    @Transient
    Session currentSession;
    ...
}
[edit] Example: Using <transient> XML
<entity class="Employee">
    <attributes>
        <id name="id"/>
        <transient name="currentSession"/>
        ...
    </attributes>
</entity>
Elug javaspec icon.gif

For more information, see Section 11.1.48 "Transient Annotation" in the JPA Specification.


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