Model does not update within ng-if

问题:

I've got a strange behavior in an angular application and I don't know if that's a bug or a known limitation:

'use strict';

var ctrl = function ($scope) {
    $scope.foo = false;
};

<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.2.23/angular.min.js"></script>
<div ng-app ng-controller="ctrl">
  foo: {{foo}}
  <div ng-if="foo" style="background-color: #f00;">
    <p>foo</p>
  </div>
  <div ng-if="!foo">
    <br/><button ng-click="foo = true;">Show foo</button>
  </div>
  <button ng-click="foo = true">Show foo</button>
</div>

http://jsfiddle.net/78R52/

I would expect that clicking one of the buttons would set foo = true, but clicking the first button (within the ng-if="!foo") doesn't change the model.

Tested version is 1.2.1.

回答1:

ng-if has its own scope, so you need to use:

<br/><button ng-click="$parent.foo = true;">Show foo</button>

Updated fiddle: http://jsfiddle.net/78R52/1/

回答2:

Ah, ng-if creates a new scope! So, "there has to be a dot in the model name"!

http://jsfiddle.net/78R52/2/

回答3:

As others have said, ng-if has its own scope. What i want to say, it's a bad practice to put expressions in the view. The good practice is to have a scope function that's called within the view.

var ctrl = function($scope){
$scope.foo = false;
$scope.fn = fn;
function fn(){
$scope.foo = true;
}
/////

<div ng-app ng-controller="ctrl">
  foo: {{foo}}
  <div ng-if="foo" style="background-color: #f00;">
    <p>foo</p>
  </div>
  <div ng-if="!foo">
    <br/><button ng-click="fn()">Show foo</button>
  </div>
  <button ng-click="fn()">Show foo</button>
</div>