package org.trails.descriptor.annotation;

 import java.lang.annotation.ElementType;

 import java.lang.annotation.Retention;

 import java.lang.annotation.RetentionPolicy;

 import java.lang.annotation.Target;

 /**

  * Annotation used to initialize a field based on an OGNL expression, usually

  * another field.

  * <p/>

  * For example, assume you have a car of certain model made by certain make.

  * The car has a relation to the model, but not the make. So you create a

  * transient property make initialized by model.make.<br>

  *

  * @author pruggia

  * @InitialValue("model.make")<br> This expression is only evaluated when editing the entity.

  * <p/>

  * See also {@link PossibleValues}.

  */

 @Retention(RetentionPolicy.RUNTIME)

 @Target({ElementType.FIELD, ElementType.METHOD})

 @DescriptorAnnotation(InitialValueAnnotationHandler.class)

 public @interface InitialValue

 {

         /**

          * The expression that when executed provides the initial value for the

          * property.

          */

         String value();

 }