Add directives from directive in AngularJS

In cases where you have multiple directives on a single DOM element and where theorder in which they’re applied matters, you can use the priority property to order theirapplication. Higher numbers run first. The default priority is 0 if you don’t specify one.

EDIT: after the discussion, here's the complete working solution. The key was to remove the attribute: element.removeAttr("common-things");, and also element.removeAttr("data-common-things"); (in case users specify data-common-things in the html)

angular.module('app')  .directive('commonThings', function ($compile) {    return {      restrict: 'A',      replace: false,       terminal: true, //this setting is important, see explanation below      priority: 1000, //this setting is important, see explanation below      compile: function compile(element, attrs) {        element.attr('tooltip', '{{dt()}}');        element.attr('tooltip-placement', 'bottom');        element.removeAttr("common-things"); //remove the attribute to avoid indefinite loop        element.removeAttr("data-common-things"); //also remove the same attribute with data- prefix in case users specify data-common-things in the html        return {          pre: function preLink(scope, iElement, iAttrs, controller) {  },          post: function postLink(scope, iElement, iAttrs, controller) {              $compile(iElement)(scope);          }        };      }    };  });

Working plunker is available at: http://plnkr.co/edit/Q13bUt?p=preview

Or:

angular.module('app')  .directive('commonThings', function ($compile) {    return {      restrict: 'A',      replace: false,      terminal: true,      priority: 1000,      link: function link(scope,element, attrs) {        element.attr('tooltip', '{{dt()}}');        element.attr('tooltip-placement', 'bottom');        element.removeAttr("common-things"); //remove the attribute to avoid indefinite loop        element.removeAttr("data-common-things"); //also remove the same attribute with data- prefix in case users specify data-common-things in the html        $compile(element)(scope);      }    };  });

DEMO

Explanation why we have to set terminal: true and priority: 1000 (a high number):

When the DOM is ready, angular walks the DOM to identify all registered directives and compile the directives one by one based on priority if these directives are on the same element. We set our custom directive's priority to a high number to ensure that it will be compiled first and with terminal: true, the other directives will be skipped after this directive is compiled.

When our custom directive is compiled, it will modify the element by adding directives and removing itself and use $compile service to compile all the directives (including those that were skipped).

If we don't set terminal:true and priority: 1000, there is a chance that some directives are compiled before our custom directive. And when our custom directive uses $compile to compile the element => compile again the already compiled directives. This will cause unpredictable behavior especially if the directives compiled before our custom directive have already transformed the DOM.

For more information about priority and terminal, check out How to understand the `terminal` of directive?

An example of a directive that also modifies the template is ng-repeat (priority = 1000), when ng-repeat is compiled, ng-repeat make copies of the template element before other directives get applied.

Thanks to @Izhaki's comment, here is the reference to ngRepeat source code: https://github.com/angular/angular.js/blob/master/src/ng/directive/ngRepeat.js

You can actually handle all of this with just a simple template tag. See http://jsfiddle.net/m4ve9/ for an example. Note that I actually didn't need a compile or link property on the super-directive definition.

During the compilation process, Angular pulls in the template values before compiling, so you can attach any further directives there and Angular will take care of it for you.

If this is a super directive that needs to preserve the original internal content, you can use transclude : true and replace the inside with <ng-transclude></ng-transclude>

Hope that helps, let me know if anything is unclear

Alex

Here's a solution that moves the directives that need to be added dynamically, into the view and also adds some optional (basic) conditional-logic. This keeps the directive clean with no hard-coded logic.

The directive takes an array of objects, each object contains the name of the directive to be added and the value to pass to it (if any).

I was struggling to think of a use-case for a directive like this until I thought that it might be useful to add some conditional logic that only adds a directive based on some condition (though the answer below is still contrived). I added an optional if property that should contain a bool value, expression or function (e.g. defined in your controller) that determines if the directive should be added or not.

I'm also using attrs.$attr.dynamicDirectives to get the exact attribute declaration used to add the directive (e.g. data-dynamic-directive, dynamic-directive) without hard-coding string values to check for.

Plunker Demo

angular.module('plunker', ['ui.bootstrap'])    .controller('DatepickerDemoCtrl', ['$scope',        function($scope) {            $scope.dt = function() {                return new Date();            };            $scope.selects = [1, 2, 3, 4];            $scope.el = 2;            // For use with our dynamic-directive            $scope.selectIsRequired = true;            $scope.addTooltip = function() {                return true;            };        }    ])    .directive('dynamicDirectives', ['$compile',        function($compile) {                         var addDirectiveToElement = function(scope, element, dir) {                var propName;                if (dir.if) {                    propName = Object.keys(dir)[1];                    var addDirective = scope.$eval(dir.if);                    if (addDirective) {                        element.attr(propName, dir[propName]);                    }                } else { // No condition, just add directive                    propName = Object.keys(dir)[0];                    element.attr(propName, dir[propName]);                }            };                        var linker = function(scope, element, attrs) {                var directives = scope.$eval(attrs.dynamicDirectives);                        if (!directives || !angular.isArray(directives)) {                    return $compile(element)(scope);                }                               // Add all directives in the array                angular.forEach(directives, function(dir){                    addDirectiveToElement(scope, element, dir);                });                                // Remove attribute used to add this directive                element.removeAttr(attrs.$attr.dynamicDirectives);                // Compile element to run other directives                $compile(element)(scope);            };                    return {                priority: 1001, // Run before other directives e.g.  ng-repeat                terminal: true, // Stop other directives running                link: linker            };        }    ]);

<!doctype html><html ng-app="plunker"><head>    <script src="//code.angularjs.org/1.2.20/angular.js"></script>    <script src="//angular-ui.github.io/bootstrap/ui-bootstrap-tpls-0.6.0.js"></script>    <script src="example.js"></script>    <link href="//netdna.bootstrapcdn.com/twitter-bootstrap/2.3.1/css/bootstrap-combined.min.css" rel="stylesheet"></head><body>    <div data-ng-controller="DatepickerDemoCtrl">        <select data-ng-options="s for s in selects" data-ng-model="el"             data-dynamic-directives="[                { 'if' : 'selectIsRequired', 'ng-required' : '{{selectIsRequired}}' },                { 'tooltip-placement' : 'bottom' },                { 'if' : 'addTooltip()', 'tooltip' : '{{ dt() }}' }            ]">            <option value=""></option>        </select>    </div></body></html>