角度 ng-repeat 表达式作为变量 [英] angular ng-repeat expressions as variables

问题描述

我正在尝试做这样的事情:

I'm trying to do something like this:

<ul>
    <li ng-repeat="{{myRepeatExpression}}">{{row.name}}</li>
</ul>

但是因为 ng-repeat 逻辑处于指令的编译状态，它将 {{myRepeatExpression}} 视为普通字符串而不是变量.这显然行不通.

But because the ng-repeat logic is in the compile state of the directive it treats the {{myRepeatExpression}} as a normal string instead of a variable. Which doesn't work, obviously.

有什么解决方法吗?

推荐答案

您只能使用 ng-repeat 而不是 interpolated 值来使用和表达.现在为了创建一个动态的可重复列表，您可以尝试:

You can only use and expression with ng-repeat and not an interpolated value. Now in order to create a dynamic repeatable list you can try either:

1. 使用在 ng-repeat 中动态返回列表的函数 - 这可能更昂贵，因为 angular 需要先调用该函数，然后在执行以下操作时确定集合是否已更改$digest 循环
2. $watch 用于触发列表更改的作用域上的特定变量 - 可能更有效，但如果您的动态列表依赖于多个变量，它会变得更加冗长和可能会导致在需要新变量时忘记添加新 $watch 的潜在错误

1. using a function that returns the list dynamically in the ng-repeat - this is potentially more expensive since angular needs to call the function first then determine if the collection has changed when doing a $digest cycle
2. $watch for a particular variable on the scope that trigger a change of the list - potentially more efficient but if your dynamic list depends on more than one variable it can get more verbose and can lead to potential bugs from forgetting to add a new $watch when a new variable is required

演示plunker

JS:

app.controller('MainCtrl', function($scope) {
  var values1 = [{name:'First'}, {name:'Second'}];
  var values2 = [{name:'Third'}, {name:'Fourth'}, {name:'Fifth'}];

  //1. function way
  $scope.getValues = function(id) {
    if(id === 1) {
      return values1;
    }
    if(id === 2) {
      return values2;
    }
  }

  //2. watch way
  $scope.values = undefined;
  $scope.$watch('id', function(newVal) {
    $scope.values = $scope.getValues(newVal);
  });
});

HTML:

<!-- Here we pass the required value directly to the function -->
<!-- this is not mandatory as you can use other scope variables and/or private variables -->
<ul>
  <li ng-repeat="v in getValues(id)">{{v.name}}</li>
</ul>
<!-- Nothing special here, plain old ng-repeat -->
<ul>
  <li ng-repeat="v in values">{{v.name}}</li>
</ul>

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