Validation strategies with AngularJS

Question

I'm evaluating AngularJS and so far I'm very enthusiastic about it. But there's something missing on the validation front: the available options, such as the built-in mechanisms and the AngularUI initiative, implement validators through directives and, as such, every validation should be declared in the view:

<form ng-controller="SomeController">
    <!-- Notice the 'required' attribute directive below: -->
    <input type="text" ng-model="user.name" name="uName" required />
</form>

In this example, the view is defining that user.name is required. It's like saying the view defines the proper shape of the model. Isn't it a little backwards? Shouldn't the view reflect the states, including error states when it's the case?

Am I mistaken? I'm wondering if it's possible to apply any validators in the controller, signaling the model's data as valid/invalid, and updating the view accordingly (painting form controls with red, showing error messages, clearing previous errors and so on). I'm assuming AngularJS is powerful enough for this, but in the docs and samples so far I just haven't seen anything like I've described above. Thanks!

Answer 1

I guess its all about perspective. The way I see it is, you are defining a view which contains a form and that form contains an input of type text. It is this text input that you are marking as required. If you note, angular does not care if the text is user.name or user.age or whatever else. Its just associating that text input with required. So its just validating that text input and the model associated with that model is the final result ( the place where the value goes in if the validation passes! ).

Have a look at

http://docs.angularjs.org/guide/forms

for custom form validations, if you want to to be doing validations that are not the default ones.

Since you already know the view that is getting produced in advance ( lets call it at compile time! ) , you can associate all validators in the view and hence wouldnt have to do it in the controller (which perhaps is for run-time validation! ).