From: David E Jones <d...@me.com>
Subject: Re: Discussion: Entity Engine Field Validators
To: dev@ofbiz.apache.org
Date: Saturday, June 26, 2010, 9:58 AM
The validators are only used in the WebTools Entity Data
Maintenance screens.
They are intentionally not used in other parts of the
project as validation is best in the logic layer, and not in
the data layer (makes things far more reusable and
flexible).
I actually consider these to be a bad design from very
early on in the project when the entity engine was one of
the only tools in the framework, and IMO it would be better
to remove them than to support them everywhere.
-David
On Jun 26, 2010, at 10:54 AM, Adrian Crum wrote:
The entity engine allows you to specify field
validators in two places: in the fieldtypeXxx.xml files and
in the the entity definition.
The validators in the fieldtype files are not used as
far as I can tell.
The validators in the entity definitions require
complicated client code to use them - they are not used
automatically by the entity engine.
The bottom line is, specifying a validator in either
location does absolutely nothing. I don't know if this was
designed this way or not.
I have a design in mind that I think will be
better...
1. Create a validator interface that can be used
throughout the project:
public interface Validator {
void isValid(Object obj;
}
The isValid method throws an IllegalArgumentException
if the object is not valid.
2. Set up a library of commonly used validators and
put them in a Validator factory. Modify ModelField and
ModelFieldType so they load validators from the factory.
3. Have ModelField and ModelFieldType implement
Validator. Those classes delegate the isValid method call to
their contained validators.
4. Modify GenericEntity.set method to call the
ModelField's isValid method.
The advantages to this approach are:
1. Validators are reusable. The same validators could
be used on service parameters for example.
2. Client code is shielded from validation details.
Just call the isValid method.
3. OFBiz users can implement custom Validator
implementations and add them to the Validator factory.
What do you think?
-Adrian
