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

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* [http://www.eclipse.org/eclipselink/api/latest/javax/persistence/Lob.html @Lob]
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By default, EclipseLink persistence provider assumes that all persistent data can be represented as typical database data types.
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By default, the EclipseLink persistence provider assumes that all persistent data can be represented as typical database data types.
  
 
Use the <tt>@Lob</tt> annotation with the [[EclipseLink/UserGuide/JPA/Basic_JPA_Development/Mapping/Basic_Mappings|<tt>@Basic</tt> mapping]] to specify that a persistent property or field should be persisted as a large object to a database-supported large object type.
 
Use the <tt>@Lob</tt> annotation with the [[EclipseLink/UserGuide/JPA/Basic_JPA_Development/Mapping/Basic_Mappings|<tt>@Basic</tt> mapping]] to specify that a persistent property or field should be persisted as a large object to a database-supported large object type.

Revision as of 10:34, 2 May 2011


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Elug api package icon.png Key API


@Lob

By default, the EclipseLink persistence provider assumes that all persistent data can be represented as typical database data types.

Use the @Lob annotation with the @Basic mapping to specify that a persistent property or field should be persisted as a large object to a database-supported large object type.

A Lob may be either a binary or character type. The persistence provider infers the Lob type from the type of the persistent field or property.

For String and character-based types, the default is Clob. In all other cases, the default is Blob.

You can also use the @Column attribute columnDefinition to further refine the Lob type.

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For more information, see Section 9.1.5 "Column Annotation" in the JPA Specification.

The @Lob annotation does not have attributes.

The following example shows how to use this @Lob annotation to specify that persistent field pic should be persisted as a Blob.

Example: @Lob
 @Entity
 public class Employee implements Serializable {
     ...
     @Lob
     @Basic(fetch=LAZY)
     @Column(name="EMP_PIC", columnDefinition="BLOB NOT NULL")
     protected byte[] pic;
     ...
 }
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For more information, see Section 9.1.20 "Temporal Annotation" in the JPA Specification.


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