Is it possible to extend Breeze Metadata received from the server?

Question

Wondering if anyone knows of any way to extend or configure Breeze so that the server returns additional info in the entity metadata? I'd like to use this additional data to assist with validation.

Assume I have an entity model like so with some Data Annotations applied:

public class Person {    
    [RegularExpression(@"^$|^http\://[a-zA-Z0-9\-\.]+\.[a-zA-Z]{2,3}(/\S*)?", 
      ErrorMessage="The Website address does not appear to be valid.")]
    public string Website { get; set; }

    [Required(ErrorMessage="The Name field is required."), 
      MaxLength(150, ErrorMessage = "The Name field cannot exceed 150 characters."), 
      MinLength(5, ErrorMessage = "The Name field must be at least 5 characters.")]
    public string Name { get; set; }
    //...
}

Right now, Breeze only hooks up a MaxLength and Required Validator based on the metadata it receives since this is all it supports out of the box. If Breeze could include in the metadata the info described in the Data Annotation Attributes on the server entity, I'm thinking it would then be possible for Breeze to automatically add additional stock validators to the client EntityType (e.g. for RegEx, Range, MinLength, etc... ). This would cover the majority of basic validation use cases. Or, it could also allow developers to inspect the metadata and pull out useful info like the regEx string which we could use to hook up our own custom RegEx validator.

Also, is there any way to have Breeze include the value of the ErrorMessage validation attribute property in the metadata and then have the breeze client use that instead of the default required and maxLength messageTemplates? This would mean you would only have to define the error message in one place on the server and wouldn't have to customize it for each entity.

I'm trying to avoid having to create and register a bunch of custom validators on the client for what seems like basic validations that could be handled by Breeze automatically.

Thanks, Richard

Jay Traband Jay Traband · Accepted Answer · 2013-03-18T16:15:25

It's a great question.

We haven't yet done a good job of documenting how the server serializes metadata but this should be coming "real soon now". However, if you take a look at the json coming over the wire you'll notice that validators are serialized simply by name. This name is then looked up among the registered validators ( or validator factories) on the client and then added to the client side metadata. So the idea would be to register you validator "implementation" on the client with a unique name, and then have the server reference this name when sending metadata down from the server.

Hopefully this will be clearer in a week or so once we have documented how to create your own server side metadata to send down to the client.

Is it possible to extend Breeze Metadata received from the server?

2 Answers