带有对象数组的 ngOptions 不设置第一个值

Question

我有一个对象数组，格式如下：

[
  {key: 'SC', name: 'Santa Catarina'},
  {key: 'SP', name: 'São Paulo'},
  {key: 'RJ', name: 'Rio de Janeiro'}
]

我想使用 select 和 ng-options 来显示这些值：

<select ng-model="vm.state"
    ng-options="state.name for state in vm.states">
</select>

但是，如果 vm.state 已经有一个值，则 select 不会以它 selected 开头。有谁知道如何实现它？

谢谢！ :)

Answer 1

要自己设置，类似

$scope.states=[...]
$scope.state=$scope.states[0]

Answer 2

首先你必须自己设置它，因为 vm.state 将从你的 vm.state 中获取值。你可以使用 ng-init 来设置它。

  <select ng-model="vm.state"
        ng-options="state.name for state in vm.states" ng-init="vm.state = $scope.states[0]">
    </select>

Answer 3

在这种情况下，您可以使用 track by，从某些 ajax 调用中检索选定的对象。

<select ng-model="vm.state"
      ng-options="state.name for state in vm.states track by state.key">
</select>

NOTE: track by will not work if you are using select as in ng-options expression.`

ngOptions with array of objects does not set the first value