AngularJS - Create a directive that uses ng-model

Angularjs Problem Overview

I am trying to create a directive that would create an input field with the same ng-model as the element that creates the directive.

Here's what I came up with so far:

HTML

<!doctype html>
<html ng-app="plunker" >
<head>
  <meta charset="utf-8">
  <title>AngularJS Plunker</title>
  <link rel="stylesheet" href="style.css">
  <script>document.write("<base href=\"" + document.location + "\" />");</script>
  <script src="https://ajax.googleapis.com/ajax/libs/jquery/1.8.3/jquery.min.js"></script>
  <script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.0.2/angular.js"></script>
  <script src="app.js"></script>
</head>
<body ng-controller="MainCtrl">
  This scope value <input ng-model="name">
  <my-directive ng-model="name"></my-directive>
</body>
</html>

JavaScript

var app = angular.module('plunker', []);

app.controller('MainCtrl', function($scope) {
  $scope.name = "Felipe";
});

app.directive('myDirective', function($compile) {
  return {
    restrict: 'E',
    scope: {
      ngModel: '='
    },
    template: '<div class="some"><label for="{{id}}">{{label}}</label>' +
      '<input id="{{id}}" ng-model="value"></div>',
    replace: true,
    require: 'ngModel',
    link: function($scope, elem, attr, ctrl) {
      $scope.label = attr.ngModel;
      $scope.id = attr.ngModel;
      console.debug(attr.ngModel);
      console.debug($scope.$parent.$eval(attr.ngModel));
      var textField = $('input', elem).
        attr('ng-model', attr.ngModel).
        val($scope.$parent.$eval(attr.ngModel));

      $compile(textField)($scope.$parent);
    }
  };
});

However, I am not confident this is the right way to handle this scenario, and there is a bug that my control is not getting initialized with the value of the ng-model target field.

Here's a Plunker of the code above: http://plnkr.co/edit/IvrDbJ

What's the correct way of handling this?

EDIT: After removing the ng-model="value" from the template, this seems to be working fine. However, I will keep this question open because I want to double check this is the right way of doing this.

Angularjs Solutions

Solution 1 - Angularjs

EDIT: This answer is old and likely out of date. Just a heads up so it doesn't lead folks astray. I no longer use Angular so I'm not in a good position to make improvements.

It's actually pretty good logic but you can simplify things a bit.

###Directive

var app = angular.module('plunker', []);

app.controller('MainCtrl', function($scope) {
  $scope.model = { name: 'World' };
  $scope.name = "Felipe";
});

app.directive('myDirective', function($compile) {
  return {
    restrict: 'AE', //attribute or element
    scope: {
      myDirectiveVar: '=',
     //bindAttr: '='
    },
    template: '<div class="some">' +
      '<input ng-model="myDirectiveVar"></div>',
    replace: true,
    //require: 'ngModel',
    link: function($scope, elem, attr, ctrl) {
      console.debug($scope);
      //var textField = $('input', elem).attr('ng-model', 'myDirectiveVar');
      // $compile(textField)($scope.$parent);
    }
  };
});

###Html with directive

<body ng-controller="MainCtrl">
  This scope value <input ng-model="name">
  <my-directive my-directive-var="name"></my-directive>
</body>

###CSS

.some {
  border: 1px solid #cacaca;
  padding: 10px;
}

You can see it in action with this Plunker.

Here's what I see:

I understand why you want to use 'ng-model' but in your case it's not necessary. ng-model is to link existing html elements with a value in the scope. Since you're creating a directive yourself you're creating a 'new' html element, so you don't need ng-model.

EDIT As mentioned by Mark in his comment, there's no reason that you can't use ng-model, just to keep with convention.

By explicitly creating a scope in your directive (an 'isolated' scope), the directive's scope cannot access the 'name' variable on the parent scope (which is why, I think, you wanted to use ng-model).
I removed ngModel from your directive and replaced it with a custom name that you can change to whatever.
The thing that makes it all still work is that '=' sign in the scope. Checkout the docs docs under the 'scope' header.

In general, your directives should use the isolated scope (which you did correctly) and use the '=' type scope if you want a value in your directive to always map to a value in the parent scope.

Solution 2 - Angularjs

I took a combo of all answers, and now have two ways of doing this with the ng-model attribute:

With a new scope which copies ngModel
With the same scope which does a compile on link

var app = angular.module('model', []);

app.controller('MainCtrl', function($scope) {
  $scope.name = "Felipe";
  $scope.label = "The Label";
});

app.directive('myDirectiveWithScope', function() {
  return {
    restrict: 'E',
    scope: {
      ngModel: '=',
    },
    // Notice how label isn't copied
    template: '<div class="some"><label>{{label}}: <input ng-model="ngModel"></label></div>',
    replace: true
  };
});
app.directive('myDirectiveWithChildScope', function($compile) {
  return {
    restrict: 'E',
    scope: true,
    // Notice how label is visible in the scope
    template: '<div class="some"><label>{{label}}: <input></label></div>',
    replace: true,
    link: function ($scope, element) {
      // element will be the div which gets the ng-model on the original directive
      var model = element.attr('ng-model');
      $('input',element).attr('ng-model', model);
      return $compile(element)($scope);
    }
  };
});
app.directive('myDirectiveWithoutScope', function($compile) {
  return {
    restrict: 'E',
    template: '<div class="some"><label>{{$parent.label}}: <input></label></div>',
    replace: true,
    link: function ($scope, element) {
      // element will be the div which gets the ng-model on the original directive
      var model = element.attr('ng-model');
      return $compile($('input',element).attr('ng-model', model))($scope);
    }
  };
});
app.directive('myReplacedDirectiveIsolate', function($compile) {
  return {
    restrict: 'E',
    scope: {},
    template: '<input class="some">',
    replace: true
  };
});
app.directive('myReplacedDirectiveChild', function($compile) {
  return {
    restrict: 'E',
    scope: true,
    template: '<input class="some">',
    replace: true
  };
});
app.directive('myReplacedDirective', function($compile) {
  return {
    restrict: 'E',
    template: '<input class="some">',
    replace: true
  };
});

.some {
  border: 1px solid #cacaca;
  padding: 10px;
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.2.0/angular.min.js"></script>
<div ng-app="model" ng-controller="MainCtrl">
  This scope value <input ng-model="name">, label: "{{label}}"
  <ul>
    <li>With new isolate scope (label from parent):
      <my-directive-with-scope ng-model="name"></my-directive-with-scope>
    </li>
    <li>With new child scope:
      <my-directive-with-child-scope ng-model="name"></my-directive-with-child-scope>
    </li>
    <li>Same scope:
      <my-directive-without-scope ng-model="name"></my-directive-without-scope>
    </li>
    <li>Replaced element, isolate scope:
      <my-replaced-directive-isolate ng-model="name"></my-replaced-directive-isolate>
    </li>
    <li>Replaced element, child scope:
      <my-replaced-directive-child ng-model="name"></my-replaced-directive-child>
    </li>
    <li>Replaced element, same scope:
      <my-replaced-directive ng-model="name"></my-replaced-directive>
    </li>
  </ul>
  <p>Try typing in the child scope ones, they copy the value into the child scope which breaks the link with the parent scope.
  <p>Also notice how removing jQuery makes it so only the new-isolate-scope version works.
  <p>Finally, note that the replace+isolate scope only works in AngularJS >=1.2.0
</div>

I'm not sure I like the compiling at link time. However, if you're just replacing the element with another you don't need to do that.

All in all I prefer the first one. Simply set scope to {ngModel:"="} and set ng-model="ngModel" where you want it in your template.

Update: I inlined the code snippet and updated it for Angular v1.2. Turns out that isolate scope is still best, especially when not using jQuery. So it boils down to:

Are you replacing a single element: Just replace it, leave the scope alone, but note that replace is deprecated for v2.0:

  app.directive('myReplacedDirective', function($compile) {
    return {
      restrict: 'E',
      template: '<input class="some">',
      replace: true
    };
  });

Otherwise use this:

  app.directive('myDirectiveWithScope', function() {
    return {
      restrict: 'E',
      scope: {
        ngModel: '=',
      },
      template: '<div class="some"><input ng-model="ngModel"></div>'
    };
  });

Solution 3 - Angularjs

it' s not so complicated: in your dirctive, use an alias: scope:{alias:'=ngModel'}

.directive('dateselect', function () {
return {
    restrict: 'E',
    transclude: true,
    scope:{
        bindModel:'=ngModel'
    },
    template:'<input ng-model="bindModel"/>'
}

in your html, use as normal

<dateselect ng-model="birthday"></dateselect>

Solution 4 - Angularjs

You only need ng-model when you need to access the model's $viewValue or $modelValue. See NgModelController. And in that case, you would use require: '^ngModel'.

For the rest, see Roys answer.

Solution 5 - Angularjs

This is a little late answer, but I found this awesome post about NgModelController, which I think is exactly what you were looking for.

TL;DR - you can use require: 'ngModel' and then add NgModelController to your linking function:

link: function(scope, iElement, iAttrs, ngModelCtrl) {
  //TODO
}

This way, no hacks needed - you are using Angular's built-in ng-model

Solution 6 - Angularjs

I wouldn't set the ngmodel via an attribute, you can specify it right in the template:

template: '<div class="some"><label>{{label}}</label><input data-ng-model="ngModel"></div>',

plunker: http://plnkr.co/edit/9vtmnw?p=preview

Solution 7 - Angularjs

Since Angular 1.5 it's possible to use Components. Components are the-way-to-go and solves this problem easy.

<myComponent data-ng-model="$ctrl.result"></myComponent>

app.component("myComponent", {
    templateUrl: "yourTemplate.html",
    controller: YourController,
    bindings: {
        ngModel: "="
    }
});

Inside YourController all you need to do is:

this.ngModel = "x"; //$scope.$apply("$ctrl.ngModel"); if needed

Solution 8 - Angularjs

Creating an isolate scope is undesirable. I would avoid using the scope attribute and do something like this. scope:true gives you a new child scope but not isolate. Then use parse to point a local scope variable to the same object the user has supplied to the ngModel attribute.

app.directive('myDir', ['$parse', function ($parse) {
	return {
		restrict: 'EA',
		scope: true,
		link: function (scope, elem, attrs) {
			if(!attrs.ngModel) {return;}
			var model = $parse(attrs.ngModel);
			scope.model = model(scope);
		}
	};
}]);

Content Type	Original Author	Original Content on Stackoverflow
Question	kolrie	View Question on Stackoverflow
Solution 1 - Angularjs	Roy Truelove	View Answer on Stackoverflow
Solution 2 - Angularjs	w00t	View Answer on Stackoverflow
Solution 3 - Angularjs	AiShiguang	View Answer on Stackoverflow
Solution 4 - Angularjs	asgoth	View Answer on Stackoverflow
Solution 5 - Angularjs	Yaniv Efraim	View Answer on Stackoverflow
Solution 6 - Angularjs	Mathew Berg	View Answer on Stackoverflow
Solution 7 - Angularjs	Niels Steenbeek	View Answer on Stackoverflow
Solution 8 - Angularjs	btm1	View Answer on Stackoverflow