Copy attributes from custom directive to input

Question

I have a custom driective which wraps input with div and adds a label.

<my-input label="My Label" name="myname" ng-model="mymodel" ng-pattern="/^[a-z]+$/">

I want to use optionally all of possible angular directives for input like ng-pattern, ng-minlength etc. Now it looks like this:

app.directive('myInput',[function () {
    return {
        restrict: "E",
        replace: true,
        scope: {
            ngModel: '=',
            name: '@',

            ngMinlength: '=',
            ngMaxlength: '=',
            ngPattern: '@',                
            label: '@'                
        },
        compile: function(element, attrs){

            if(!_.isUndefined(attrs['ngMinlength'])) {
                element.find('input').attr('ng-minlength', 'ngMinlength');
            }
            if(!_.isUndefined(attrs['ngMaxlength'])) {
                element.find('input').attr('ng-maxlength', 'ngMaxlength');
            }                
            if(!_.isUndefined(attrs['ngPattern'])) {
                element.find('input').attr('ng-pattern', attrs['ngPattern']);
            }               


        },
        template: '<div class="form-group">'
        + '<label>{{ label | translate }}</label>'
        + '<div>'
        + '<input type="text" class="form-control input-sm" name="{{ name }}" ng-model="ngModel">'           
        + '</div></div>'
    };
}]);

The problem is that I want use ng-pattern exactly the same as ng-pattern works in input, so I want to have possibility to use regexp in the ng-pattern and also scope variable with pattern ($scope.mypattern = /^[a-z]+$/; ... ng-pattern="mypattern"). How to manage this?

I want both working:

1.

<my-input label="My Label" name="myname" ng-model="mymodel" ng-pattern="/^[a-z]+$/">

2.

$scope.myPattern = /^[a-z]+$/
...
<my-input label="My Label" name="myname" ng-model="mymodel" ng-pattern="myPattern">

Answer 1

I have three answers for you.

1. In general, it is not recommended to support both a model property, and directly a String. This case is handled by a = declaration in your directive scope, and if you want to pass a String, you would use simple quotes. For instance ngBind works like this: ng-bind="someModel" or ng-bind="'some string'"

2. If you really want to, you can try to parse the expression. If it is parsable, it means it is a scope model. Otherwise, it is likely a string. See working example in the code snippet below:

angular.module('test', [])

.controller('test', function($scope) {
  $scope.model = "string from scope model";
})

.directive('turlututu', function($parse) {
 return {
   restrict: 'E',
   scope: {},
   template: '<div class="tu">{{content}}</div>',
   link: function(scope, elem, attrs) {
     try {
       scope.content = $parse(attrs.text)(scope.$parent);
     } catch(err) {
     } finally {
       if (!scope.content) {
         scope.content = attrs.text;
       }
     }
   }
 };
});

body { font-family: monospace; }

.tu { padding: 10px; margin: 10px; background: #f5f5f5; border-bottom: 2px solid #e5e5e5; }

<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.2.23/angular.min.js"></script>
<div ng-app="test" ng-controller="test">
  
  <turlututu text="hardcoded string"></turlututu>
  <turlututu text="model"></turlututu>
  
</div>

3. In the case of ngPattern, because curiosity in code will always help you, you can see in the source code of Angular that they test the attribute first character: if it is / it is considered a regexp, otherwise a scope model (see example below)

angular.module('test', [])

.controller('test', function($scope) {
  $scope.model = /[a-z]*/;
})

.directive('turlututu', function($parse) {
 return {
   restrict: 'E',
   scope: {},
   template: '<div class="tu">{{content}}</div>',
   link: function(scope, elem, attrs) {
     if (attrs.regexp.charAt(0) === '/') {
       scope.reg = new RegExp( attrs.regexp.substring(1, attrs.regexp.length-1) );
     } else {     
       scope.reg = new RegExp( $parse(attrs.regexp)(scope.$parent) );
     }
     
     scope.content = scope.reg.toString()
   }
 };
});

body { font-family: monospace; }

.tu { padding: 10px; margin: 10px; background: #f5f5f5; border-bottom: 2px solid #e5e5e5; }

<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.2.23/angular.min.js"></script>
<div ng-app="test" ng-controller="test">
  
  <turlututu regexp="/[0-9]*/"></turlututu>
  <turlututu regexp="model"></turlututu>
  
</div>