如何在ng-if和变量中使用过滤器? [英] How to use filter in ng-if and variable?

问题描述

在此示例中，我在 ng-repeat 中使用过滤器，但是如何在变量和ng-if中使用它，例如:

In this example, I use filter in the ng-repeat, but how do I use it in a variable and ng-if, something like:

{{languages.length | filter: {available: true}}}

和

ng-if="languages.length == 0 | filter: {available: true}"

请参见小提琴.

HTML

<div ng-controller="mainController">
    <div>There are {{languages.length}} languages in total.</div>
    <div>??? There are {{languages.length}} languages available.</div>
    <div ng-if="languages.length == 0">??? Sorry, there are no languages available.</div>

    <ol>
        <li ng-repeat="language in languages | filter: {available: true}">{{language.name}}</li>
    </ol>
</div>

AngularJS

$scope.languages = [
    {id:1, name:"German", available: false},    
    {id:2, name:"English", available: true},    
    {id:3, name:"French", available: false},  
    {id:4, name:"Italian", available: true},  
    {id:5, name:"Spanish", available: false}
];

推荐答案

可以尝试吗?

<div ng-controller="mainController">
    <div>There are {{languages.length}} languages in total.</div>
    <div>There are {{(languages|filter:{available:true}).length}} languages available.</div>
    <div ng-if="(languages|filter:{available:true}).length == 0">Sorry, there are no languages available.</div>

    <ol>
        <li ng-repeat="language in languages | filter: {available: true}">{{language.name}}</li>
    </ol>
</div>

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