Fetching Entities from DB in a PropertyEditor

Question

When using PropertyEditors with Spring MVC is it bad to have them fetch entities from the database? Should I instead create an empty entity and set its Id.

For instance

Answer 1

I think it is legal. I used this technice for some time, and it worked well.

But Spring 3.0 has a better concept. So called Converter (Reference Chapter 5.5 Spring 3 Type Conversion)

This converters work like one way property editors. But they are Stateless, and because of this more performat, and can be reuesed!

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Added: There is an not (yet) documented feature of Spring 3.0.>3: the org.springframework.core.convert.support.IdToEntityConverter

It is automatically registered in the ConversationService by the ConcersationServiceFactory.

This IdToEntityConverter will automatically convert everything (Object) to an Entity, if the entity!! has a static method find<entityName> which has one parameter and the return type is of type of the entity.

/**
 * Converts an entity identifier to a entity reference by calling a static finder method
 * on the target entity type.
 *
 * <p>For this converter to match, the finder method must be public, static, have the signature
 * <code>find[EntityName]([IdType])</code>, and return an instance of the desired entity type.
 *
 * @author Keith Donald
 * @since 3.0
 */

If you have doubt how to implement such a static finder method in your entity. Then have a look at Spring Roo generated entities.