com.avaje.ebean.annotation.EnumMapping Maven / Gradle / Ivy
package com.avaje.ebean.annotation;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
/**
* For mapping the values of an Enum to and from Database values.
*
* Also refer to the {@link EnumValue} approach which probably the preferred now
* (preferred over using this EnumMapping annotation).
*
*
* Both of the approaches defined in the JPA have significant problems!!!
*
*
* Using the ordinal value is VERY RISKY because that depends on the compile
* order of the enum values. Aka if you change the order of the enum values you
* have changed their ordinal values and now your DB values are WRONG - a HUGE
* disaster!!!.
*
*
* Using the String values of enums is fairly restrictive because in a Database
* these values are usually truncated into short codes (e.g. "A" short for
* "ACTIVE") so space used in the database is minimised. Making your enum names
* match the database values would give them very short less meaningful names -
* not a great solution.
*
*
* You can use this annotation to control the mapping of your enums to database
* values.
*
*
* The design of this using nameValuePairs is not optimal for safety or
* refactoring so if you have a better solution I'm all ears. The other
* solutions would probably involve modifying each enumeration with a method
* which may be ok.
*
*
* An example mapping the UserState enum.
*
*
*
* ...
* @EnumMapping(nameValuePairs="NEW=N, ACTIVE=A, INACTIVE=I")
* public enum UserState {
* NEW,
* ACTIVE,
* INACTIVE;
* }
*
*
* @see EnumValue
*/
@Target({ ElementType.TYPE })
@Retention(RetentionPolicy.RUNTIME)
public @interface EnumMapping {
/**
* A comma delimited list of name=value pairs.
*
* e.g. "ACTIVE=A, INACTIVE=I, NEW=N".
*
*
* Where ACTIVE, INACTIVE and NEW are the enumeration values and "A", "I" and
* "N" are the database values.
*
*
* This is not really an optimal approach so if you have a better one I'm all
* ears - thanks.
*
*/
String nameValuePairs();
/**
* Defaults to mapping values to database VARCHAR type. If this is set to true
* then the values will be converted to INTEGER and mapped to the database
* integer type.
*
* e.g. "ACTIVE=1, INACTIVE=0, NEW=2".
*
*/
boolean integerType() default false;
/**
* The length of DB column if mapping to string values.
*/
int length() default 0;
}