How can I transclude into an attribute?

Question

Is is possible to somehow use ngTransclude for an attribute value, instead of replacing inner HTML content? For example this simple directive

var testapp = angular.module('testapp', [])

testapp.directive('tag', function() {
  return {
    template: '<h1><a href="{{transcludeHere}}" ng-transclude></a></h1>',
    restrict: 'E',
    transclude: true
  }
});

and use it as

<tag>foo</tag>

I want it to translate into

<h1><a href="foo">foo</a></h1>

Is there any way of doing that, or do I have to use an attribute instead of transcluding?

Here's a fiddle with the example

Answer 1

Something like this:

var testapp = angular.module('testapp', [])

testapp.directive('tag', function() {
  return {
    restrict: 'E',
    template: '<h1><a href="{{transcluded_content}}">{{transcluded_content}}</a></h1>',
    replace: true,
    transclude: true,
    compile: function compile(tElement, tAttrs, transclude) {
        return {
            pre: function(scope) {
                transclude(scope, function(clone) {
                  scope.transcluded_content = clone[0].textContent;
                });
            }
        }
    }
  }
});​

fiddle.

Answer 2

One more solution:

app.directive('tag', function($compile) {
  return {
    restrict: 'E',
    template:"<h1></h1>",
    transclude: 'element',
    replace: true,
    controller: function($scope, $element, $transclude) {
      $transclude(function(clone) {
        var a = angular.element('<a>');
        a.attr('href', clone.text());
        a.text(clone.text());        
        // If you wish to use ng directives in your <a>
        // it should be compiled
        //a.attr('ng-click', "click()");
        //$compile(a)($scope);       
        $element.append(a);
      });
    }
  };
});

Plunker: http://plnkr.co/edit/0ZfeLz?p=preview

Answer 3

I know originally your question was about transclusion, but this problem is MUCH more succinctly solved using an attribute.

var testapp = angular.module('testapp', [])

testapp.directive('tag', function() {
  return {
    template: '<h1><a href="{{url}}">{{url}}</a></h1>',
    restrict: 'E',
    scope: {
      url: '@'
    }
  }
});

and your html

<tag url="foo"></tag>

The translation:

<h1><a href="foo">foo</a></h1>

Also, with the very latest version of Angular, there is a feature called "one-time binding" that is perfect for situations just like this where you only want/need to fulfill the interpolated value one time, upon initialization. The syntax looks like this:

{{::url}}

Just replace all instances of {{url}} in your template with the above.

Answer 4

Vadim's answer can be easily fixed by using the compile function, and returning the postLink function, where tranclusion will happen.

app.directive('tag', function ($compile) {
  return {
    restrict: 'E',
    template: '<h1></h1>',
    transclude: 'element',
    replace: true,
    compile: function($element, $attrs) {
        return function ($scope, $element, $attrs, $controller, $transclude) {
          $transclude(function(clone) {
            var a = angular.element('<a></a>');
            a.attr('href', clone.text());
            a.text(clone.text());        
            // If you wish to use ng directives in your <a>
            // it should be compiled
            // a.attr('ng-click', 'click()');
            // $compile(a)($scope);
            $element.append(a);
          });
        };
    }
  };
});

Please refer to https://docs.angularjs.org/api/ng/service/$compile

The $transclude function used to be passed in the compile function, but it was deprecated, and is now in the link function.