Fer*_*c T 39 parameters scope directive callback angularjs
我创建了一个包含按钮的自定义指令.此按钮从'callback'属性指定的父作用域调用方法.
<!DOCTYPE html>
<html ng-app="app">
<head>
<title>Simple directive</title>
<script src="js/lib/angular/angular.js"></script>
<script type="text/javascript">
var app = angular.module('app', []);
app.controller('TestController', function($scope) {
$scope.doSomething = function(param) {
alert('Something called with: ' + param);
}
})
app.directive('myDirective', function() {
var ret = {
restrict: 'E',
scope: {
user: '@',
callback: '&' // bound a function from the scope
},
template: '<div>Hello {{user}}<button ng-show="hasCallback()" ng-click="callback({userData: user})">Callback</button>',
controller: function($scope) {
$scope.hasCallback2 = function() {
var t = typeof $scope.callback;
return t == 'function';
}
$scope.hasCallback = function() {
return angular.isDefined($scope.callback);
}
}
};
return ret;
});
</script>
</head>
<body ng-controller="TestController">
<my-directive user="cat" callback="doSomething(userData)"></my-directive>
<my-directive user="dog" callback="doSomething(userData)"></my-directive>
<my-directive user="pig"></my-directive>
</body>
</html>
我的问题是:
如何控制模板内按钮的可见性？如果在自定义标记中未指定回调属性,我想隐藏它(请参阅第3个my-directive标记).当我检查回调类型时,我总是得到'function'而angular.isDefined(...)也返回true.
Bul*_*lom 87
使用'&？' 如果尚未设置属性,则返回undefined.
'&'=始终定义回调函数.
'&？' =只有在html模板中定义属性时才定义回调函数.
bindToController: {
callback: '&?'
},
controller: function() {
if (this.callback === undefined) {
// attribute "callback" was not defined
}
}
注意:适用于Angular 1.4.8.我不确定它是否适用于旧版本.
Kha*_* TO 45
看看angularjs的源代码,我看到了这个:
case '&':
parentGet = $parse(attrs[attrName]);
isolateScope[scopeName] = function(locals) {
return parentGet(scope, locals);
};
break;
的parentGet是结合的函数表达式.不幸的是,这是一个局部变量,只能用于分配给isolateScope[scopeName]via闭包的函数.
一个简单的解决方案就是检查一下,而不是试图找到获得该变量的方法attrs.尝试:
link: function(scope,elem,attrs) {
scope.hasCallback = function() {
return angular.isDefined(attrs.callback);
}
}