I have this code to figure out if the element is valid or invalid in my directive :
myModule.directive('myDirective',function(){ return { restrict: 'A', scope: {}, require:'ngModel', link: function(scope,element,attrs,ctrl){ if(ctrl.$invalid){ //do something } } }}); So my problem is how can I determine which type of validation is invalid, required? max-length? my other custom-validations?
Because I need to generate proper validation-message to show.
NgModelController (or ctrl, in your example) has an $error property that you can use to see what the validation errors are.
So if the "required" validation has failed, this property will be truthy: ctrl.$error.required
It sounds like you might need to look into $error of your ctrl object.
Take a look at the following:
https://docs.angularjs.org/guide/forms#custom-validation
Look for references of $error. There are some specific examples there that might be of help to you.
For example:
<div ng-show="form.uEmail.$dirty && form.uEmail.$invalid">Invalid: <span ng-show="form.uEmail.$error.required">Tell us your email.</span> <span ng-show="form.uEmail.$error.email">This is not a valid email.</span> </div> 