How do I store angular directive in a scope variable? - angularjs

Question

I am implementing a form builder in AngularJS and need to insert and reorder directives at runtime.
Don't even know where to start looking - all examples seem to only demonstrate static tree of directives. Two options to achieve dynamic behaviour are: a) compiling and inserting templates on the fly and b) using huge ng-switch of all possible directives. Both ways are ugly.
Can anyone suggest a better implementation?
Below is JS and html code for how I think formbuilder should look in an ideal world, please help me fill in 3 instances of TODO.
JSFiddle JavaScript:
angular.module('components', [])
.directive('checkbox', function() {
return {
restrict: 'E',
template: '<div class=f><input type=checkbox>{{name}}</input></div>'
};
})
.directive('textfield', function() {
return {
restrict: 'E',
template: '<div class=f><input type=text placeholder="{{name}}"></input></div>'
};
})
function FormBuilder($scope, $locale) {
$scope.title = 'test form';
$scope.fields = [];
$scope.add_checkbox = function() {
console.log('adding checkbox');
var field = null; // TODO: how do I instantiate a directive?
$scope.fields.push(field);
};
$scope.add_textfield = function() {
console.log('adding textfield');
var field = null; // TODO: how do I instantiate a directive?
$scope.fields.push(field);
};
}
HTML:
<div ng-app=components ng-controller=FormBuilder>
<button ng:click="add_checkbox()">new checbox</button>
<button ng:click="add_textfield()">new text field</button>
<h3>{{ title }}</h3>
<checkbox></checkbox>
<textfield></textfield>
<div ng:repeat="field in fields">
<!-- TODO field.get_html() - how? -->
</div>
</div>

Answer 1

I think you have a couple ways to do this as you mentioned and since you don't want to do a switch you can create a template file for each directive. ie checkbox.html, textfield.html and put the directive in each one. Then populate your fields array with ['checkbox.html', 'textarea.html'] when you add in your loop you just simply <div ng-include='field'></div>
Here is a demo: http://plnkr.co/edit/w6n6xpng6rP5WJHDlJ3Y?p=preview
You could also create another directive where you pass in the input type and have it inject it into the template. Here is a demo of this which allows you to avoid having to declare templates and letting a directive create them based on the field type:
http://plnkr.co/jhWGuMXZTuSpz8otsVRY
<div ng:repeat="field in fields">
<master-field type='field'></master-field>
</div>
This master-field directive just compiles a template based on the value of field.
.directive('masterField', function($compile) {
return {
restrict: 'E',
replace:true,
transclude: true,
scope:{
type:'='
},
template: '<div></div>',
controller: function ( $scope, $element, $attrs ) {},
link: function(scope, element, attrs) {
element.append( $compile('<' + scope.type+ '/></' +scope.type + '>')(scope) );
}
};
})