Jump to: navigation, search

Difference between revisions of "EclipseLink/Examples/JPA/EnumToCode"

m (References)
 
(One intermediate revision by one other user not shown)
Line 1: Line 1:
 
[[Category:EclipseLink/Example/JPA|EnumToCode]]
 
[[Category:EclipseLink/Example/JPA|EnumToCode]]
  
== How to map Enum to coded values ==
+
== How to Map Enum to Coded Values ==
  
 
The JPA specification allows for mappings of Enums to database columns using the @Enumerated where the database value is either the Enum's name or ordinal value. EclipseLink allows a developer to map an enum to coded values as well using a converter.  
 
The JPA specification allows for mappings of Enums to database columns using the @Enumerated where the database value is either the Enum's name or ordinal value. EclipseLink allows a developer to map an enum to coded values as well using a converter.  
Line 58: Line 58:
  
 
==References==
 
==References==
* [http://blog.xebia.com/2009/08/28/using-enums-with-jpa-without-the-evil-ordinal/ An article on insulating you JPA entities from changes to the enum values in database]
+
* [http://blog.xebia.com/2009/08/28/using-enums-with-jpa-without-the-evil-ordinal/ An article on insulating your JPA entities from changes to the enum values in database]

Latest revision as of 20:56, 11 February 2011


How to Map Enum to Coded Values

The JPA specification allows for mappings of Enums to database columns using the @Enumerated where the database value is either the Enum's name or ordinal value. EclipseLink allows a developer to map an enum to coded values as well using a converter.

In this example the enum Gender(MALE, FEMALE) is mapped to a single character in the database where M=MALE and F=FEMALE.

Gender Enum

The Gender enum in this example is defined as:

public enum Gender {
    Female, 
    Male
}

Defining the Converter

An ObjectTypeConverter is used and can be defined in an annotation and any entity class of persistence unit. It requires a unique name across all converters in this persistence unit.

@ObjectTypeConverter(name = "gender", objectType = Gender.class, dataType = String.class, conversionValues = {
		@ConversionValue(objectValue = "Male", dataValue = "M"),
		@ConversionValue(objectValue = "Female", dataValue = "F") })

Alternatively the converter can be defined in an EclipseLink specific ORM XML file as:

<object-type-converter name="gender" object-type="model.Gender"	data-type="java.lang.String">
	<conversion-value object-value="Male" data-value="M" />
	<conversion-value object-value="Female" data-value="F" />
</object-type-converter>

Using the Converter

The converter can then be used on any attribute in the domain model of the given enum type.

@Basic
@Convert("gender")
private Gender gender = Gender.Male;

Or in the ORM.XML:

<basic name="gender">
	<column name="GENDER" />
	<convert>gender</convert>
</basic>


References