始终选择第一个值选择 vue.js

Question

我如何始终使用选择（在 vue.js 中）选择第一个项目？

 <div class="ride-item-content">
  <select v-model="ride.location_id">
    <option v-for="location in locations" v-bind:value="location.id">
      {{ location.from }} - {{ location.to }}
    </option>
  </select>
</div>

JSON

 {
  "locations": {
    "total": 2,
    "per_page": 20,
    "current_page": 1,
    "last_page": 1,
    "next_page_url": null,
    "prev_page_url": null,
    "from": 1,
    "to": 2,
    "data": [
      {
        "id": 1,
        "user_id": 1,
        "description": "sdg",
        "from": "asdf",
        "to": "asdf",
        "kmz": "12",
        "kmp": "13",
        "time": 0,
        "hour": 0,
        "maps": "www.blablabla.nl",
        "created_at": null,
        "updated_at": null
      },
      {
        "id": 2,
        "user_id": 1,
        "description": "asdf",
        "from": "asdf",
        "to": "asdf",
        "kmz": "3",
        "kmp": "1",
        "time": 1,
        "hour": 0,
        "maps": "www.test.nl",
        "created_at": null,
        "updated_at": null
      }
    ]
  }
}

- 编辑 -

<div class="ride-item-content">
  <select v-model="ride.location_id">
    <option v-for="location in locations" v-bind:selected="$index === 0 ? 'selected' : false">
      {{ location.from }} - {{ location.to }}
    </option>
  </select>
</div>

原文由 Jamie 发布，翻译遵循 CC BY-SA 4.0 许可协议

Answer 1

VueJS 1：

 <option v-for="location in locations" v-bind:value="location.id" v-bind:selected="$index === 0 ? 'selected' : false">
  {{ location.from }} - {{ location.to }}
</option>

VueJS 2：

 <option v-for="(location, index) in locations" v-bind:value="location.id" v-bind:selected="index === 0">
  {{ location.from }} - {{ location.to }}
</option>

在 Vue 1 中， $index 在 v-for 循环中自动可用。

在 Vue 2 中，您需要为索引显式声明一个变量。

原文由 J. Bruni 发布，翻译遵循 CC BY-SA 3.0 许可协议