Angularjs Form/Field validation using JavaScript function without directives

Question

Is there a way to validate a field in angular without using a directive? For example: I want to make following validation on an input field.

Answer 1

Take a look at the angularjs form documentation - http://docs.angularjs.org/guide/forms . In general, it is based on the HTML5 attributes like required, min, max, etc.

To get, for example, your first requirement done - "an empty field should show "Field must contain a value" message, yo uwould do something like that:

<input type="text" ng-model="user.name" name="uName" required /><br />
<div ng-show="form.uName.$invalid">
  <span ng-show="form.uName.$error.required">Field must contain a value.</span>
</div>

For digits only field you can use the pattern attribute with a matching regular expression (example: http://www.wufoo.com/html5/attributes/10-pattern.html).

For even number validation, I'm not sure - I think you'd have to go with custom validation for that (meaning you'd have to create a directive) or use the pattern attribute somehow.

Last but not least - remember to add novalidate to the <form> tag. Otherwise the browser will try to validate your fields as well and you don't want that:

<form ... novalidate>
 ...
</form>

Answer 2

Well you can try to create a func

<span ng-show='isEven(theText)'>Value must be an even number</span>

$scope.isEven=function(data) {
    if(data) {
        return data%2===0
    }
    return true;
}

The method can either be defined on the current controller scope or on $rootScope.

Not a very angular way, as directives would be better but i think it would work.

Answer 3

I know the question is old and I know you didn't want a directive but you may consider using a directive if it's "Angular" way... Well here is my Angular-Validation. I made a project on Github and I think that it just rocks compare to whatever is/was available...I based myself on the excellent Laravel PHP Framework and made it available under Angular... It is so crazy simple, you need 2 lines 1 line of code, 1 line for the input, 1 line for error display, that's it... never more and never less!!! Enough said, let's give some examples:

<!-- example 1 -->
<label for="input1">Email</label>
<input type="text" validation="email|min_len:3|max_len:25|required" ng-model="form1.input1" name="input1" />

<!-- example 2 -->
<label for="input2">Alphanumeric + Exact(3) + required</label>
<input type="text" validation="alpha|exact_len:3|required" ng-model="form1.input2" name="input2" />

So I can define whatever amount of validation rules (already 25+ type of validators) which I want in a simple directive validation="min_len:2|max_len:10|required|integer" and the error message will always display in the next <span> Don't you guys like it already? 1 line of code for your input, 1 line of code for the error display, you can't be simpler than that...oh and I even support your custom Regex if you want to add. Another bonus, I also support whichever trigger event you want, most common are probably onblur and onkeyup. Oh and I also support multiple localization languages via JSON external files. I really added all the imaginable features I wanted into 1 crazy simple directive.

No more clustered Form with 10 lines of code for 1 input (sorry but always found that a little extreme) when the only thing you need is 2 lines, no more, even for an input with 5 validators on it. And no worries about the form not becoming invalid, I took care of that as well, it's all handled the good "Angular" way.

Take a look at my Github project Angular-Validation... I'm sure you'll love it =)

UPDATE
Another candy bonus! To make an even more smoother user experience, I added validation on timer. The concept is simple, don't bother the user while he's typing but do validate if he makes a pause or change input (onBlur)... Love it!!!
You can even customize the timer as per your liking, I've decided to default it to 1 second within the directive but if you want to customize you can call as for example typing-limit="5000" to make a 5 sec. timeout. Full example:

<input type="text" ng-model="form1.input1" typing-limit="5000" validation="integer|required" name="input1" />
<span class="validation text-danger"></span>

UPDATE #2
Also added input match confirmation validation (ex.: password confirmation), here is a sample code

<!-- input match confirmation, as for example: password confirmation -->
<label for="input4">Password</label>
<input type="password" name="input4" ng-model="form1.input4" validation="alpha|min_len:4|required"  />
<label for="input4c">Password Confirmation</label>
<input type="password" name="input4c" ng-model="form1.input4c" validation="match:form1.input4,Password|required"  />

UPDATE #3
Refactored the directive so that the requirement of having a <span> to display the error is unnecessary, the directive now handles it by itself, see the code change reflected on top.

DEMO
Added a live demo on Plunker

Answer 4

I'm surprised no one has mentioned ui-validate

$scope.isOdd = function($value){
  return $value % 2;
}
...
<form name="myform">
  <input ng-model="myVal" name="value" required
    ng-pattern="/^[0-9]*$/" ui-validate=" 'isOdd($value)' "></input>
  <pre>{{myform.value.$error|json}}</pre>
</form>

Doesn't get any simpler than that, and it's PROPER AngularJS validation (not silly watches)

Here's a working demo