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

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By default, the EclipseLink persistence provider assumes that all persistent data can be represented as typical database data types.
 
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.
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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.
  
 
A <tt>Lob</tt> may be either a binary or character type. The persistence provider infers the <tt>Lob</tt> type from the type of the persistent field or property.
 
A <tt>Lob</tt> may be either a binary or character type. The persistence provider infers the <tt>Lob</tt> type from the type of the persistent field or property.

Revision as of 11:56, 27 October 2011

EclipseLink JPA

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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 11.1.9 "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 11.1.24 "Lob Annotation" in the JPA Specification.



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