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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> | + | 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
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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.
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; ... }
For more information, see Section 11.1.24 "Lob Annotation" in the JPA Specification.