No form validation in my angular app - angularjs

Question

I tried and searched a lot, but no solution. The form validation in my angular app still not working.
I tried for example:
<form data-ng-controller="ValidationController" name="validationForm" novalidate="novalidate">
<div class="form-group">
<label for="username">Mail</label>
<input name="username"
type="email"
data-ng-model="formData.username"
required="required">
<span ng-show="form.username.$invalid">Invalid mail address</span>
</div>
<button type="submit" class="btn btn-primary" data-ng-disabled="formData.$invalid">Submit</button>
<pre>
<tt>formData = {{formData}}</tt><br/>
<tt>formData.$valid = {{formData.$valid}}</tt><br/>
<tt>formData.username.$valid = {{formData.username.$valid}}</tt><br/>
<tt>formData.username.$error = {{formData.username.$error}}</tt><br/>
<hr>
</pre>
</form>
Another one I tried:
<div class="row">
<div class="large-12 columns">
<label>Your email</label> <input type="email" placeholder="Email"
name="email" ng-model="signup.email" ng-minlength=3 ng-maxlength=20
required />
<div class="error-container"
ng-show="signup_form.email.$dirty && signup_form.email.$invalid">
<small class="error" ng-show="signup_form.email.$error.required">
Your email is required. </small> <small class="error"
ng-show="signup_form.email.$error.minlength"> Your email is required
to be at least 3 characters </small> <small class="error"
ng-show="signup_form.email.$error.email"> That is not a valid email.
Please input a valid email. </small> <small class="error"
ng-show="signup_form.email.$error.maxlength"> Your email cannot be
longer than 20 characters </small>
</div>
</div>
</div>
But the validation does not work. If I have to enable the validation? But for this I also didn't find anything. It seems, that validation is still enabled in Angular. But why it does not work in my app? All other things works fine.
Regards
Bytecounter

Answer 1

Try this:
<form data-ng-controller="ValidationController" name="validationForm" novalidate="novalidate">
<div class="form-group">
<label for="username">Mail</label>
<input name="username"
type="email"
data-ng-model="username"
required>
<span ng-show="validationForm.username.$invalid && validationForm.username.$dirty">Invalid mail address</span>
</div>
<button type="submit" class="btn btn-primary" data-ng-disabled="formData.$invalid">Submit</button>
<pre>
<tt>formData = {{validationForm}}</tt><br/>
<tt>formData.$valid = {{validationForm.$valid}}</tt><br/>
<tt>formData.username.$valid = {{validationForm.username.$valid}}</tt><br/>
<tt>formData.username.$error = {{validationForm.username.$error}}</tt><br/>
<hr>
</pre>
</form>
Actually your form is available by its name.
Check this plnkr.

Answer 2

You have some errors there.
First:
ng-show="form.username.$invalid"
You are referencing a variable form that does not exist in your scope. You should reference validationForm:
ng-show="validationForm.username.$invalid"
Second:
data-ng-disabled="formData.$invalid"
You are referencing the model of the input, instead of it's form object, that is, again, validationForm:
data-ng-disabled="validationForm.$invalid"
That should do.