如何在 Vuex 中为 mapbox 地图设置集中状态？

Question

我刚开始使用 vuex 和 vue。我确实（大致）了解文档。我有一个具体的问题，我不确定我是否应该使用 vuex，如果是的话该怎么做。

我有一个应用程序，其中 mapbox 地图在各种布局和组件等中无所不在。因为我将制作几个 vue 单文件组件，但正在使用一个相同的 mapbox 地图实例，我认为它使得在 vuex 存储中启动和管理 mapbox 地图是有意义的。所以例如当我更改地图布局或其他内容时，它会反映在所有组件中。

当我继续朝这个方向前进时，我对一些事情感到困惑：

地图不只是一个变量/数组，而是 mapbox class 地图的一个实例。所以我假设初始状态是一个空对象，然后需要对其进行初始化。正确吗？
我想初始化是异步的，只能在页面加载后发生。这可能就是我下面的代码不起作用的原因！？

我试过以下方法：

制作了一个mapboxmap模块，

mapboxmap.js

import simple from '../../components/simplestyle'
let mapboxgl = require('mapbox-gl/dist/mapbox-gl.js')

// initial state
const state = {
  myMap: {},
  mapLoaded: false
}

const mutations = {
  loadMap (state, myMap) {
    state.myMap = myMap
    state.mapLoaded = true
  }
}

const actions = {
  loadMap (context) {
    'use strict'
    mapboxgl.accessToken = 'mysecretmapboxcode'
    let myMap = new mapboxgl.Map({
      container: 'map',
      style: simple,
      hash: true,
      center: [-74.0073, 40.7124],
      zoom: 16
    })
    context.commit('loadMap', myMap)
  }
}

export default {
  state,
  mutations,
  actions
}

作为组件：

Maplayout.vue

<template>
  <div>
    <div id='map' class='map'>
    </div>
  </div>
</template>

<script type='text/babel'>
export default {
  mounted () {
    this.computed.myMapForView.set().then(() => this.computed.myMapForView.get())
  },
  computed: {
    myMapForView: {
      // getter
      get: function () {
        return this.$store.state.myMap
      },
      // setter
      set: function () {
        this.$store.dispatch('loadMap')
      }
    }
  }
}
</script>

这是行不通的。非常感谢任何关于解决方法和具体方法的建议。

我在浏览器中收到的错误消息：

vue.runtime.common.js?d43f:433 TypeError: Cannot read property 'myMapForView' of undefined
    at VueComponent.mounted (eval at 162 (0.ce2d9bf….js:21), <anonymous>:8:18)
    at callHook (eval at <anonymous> (app.js:794), <anonymous>:2335:19)
    at Object.insert (eval at <anonymous> (app.js:794), <anonymous>:2525:5)
    at invokeInsertHook (eval at <anonymous> (app.js:794), <anonymous>:4352:28)
    at VueComponent.patch [as __patch__] (eval at <anonymous> (app.js:794), <anonymous>:4508:5)
    at VueComponent.Vue._update (eval at <anonymous> (app.js:794), <anonymous>:2222:19)
    at VueComponent.eval (eval at <anonymous> (app.js:794), <anonymous>:2189:10)
    at Watcher.get (eval at <anonymous> (app.js:794), <anonymous>:1652:27)
    at Watcher.run (eval at <anonymous> (app.js:794), <anonymous>:1721:22)
    at flushSchedulerQueue (eval at <anonymous> (app.js:794), <anonymous>:1539:13)
logError @ vue.runtime.common.js?d43f:433

编辑：从 this.computed.myMapForView 更改为 this.myMapForView 后，我在浏览器中收到以下错误消息：

vue.runtime.common.js?d43f:433 
TypeError: Cannot read property 'set' of undefined
    at VueComponent.mounted (eval at 162 (0.85b2be9….js:21), <anonymous>:6:22)
    at callHook (eval at <anonymous> (app.js:794), <anonymous>:2335:19)
    at Object.insert (eval at <anonymous> (app.js:794), <anonymous>:2525:5)
    at invokeInsertHook (eval at <anonymous> (app.js:794), <anonymous>:4352:28)
    at VueComponent.patch [as __patch__] (eval at <anonymous> (app.js:794), <anonymous>:4508:5)
    at VueComponent.Vue._update (eval at <anonymous> (app.js:794), <anonymous>:2222:19)
    at VueComponent.eval (eval at <anonymous> (app.js:794), <anonymous>:2189:10)
    at Watcher.get (eval at <anonymous> (app.js:794), <anonymous>:1652:27)
    at Watcher.run (eval at <anonymous> (app.js:794), <anonymous>:1721:22)
    at flushSchedulerQueue (eval at <anonymous> (app.js:794), <anonymous>:1539:13)
logError @ vue.runtime.common.js?d43f:433

Answer 1

在我看来 new mapboxgl.Map() 是一个异步函数并且在 vuex Actions can contain arbitrary asynchronous operations not mutations not from mutations 中。 突变处理函数必须是同步的。

因此，您应该 new mapboxgl.Map() 执行以下操作：

import simple from '../../components/simplestyle'
let mapboxgl = require('mapbox-gl/dist/mapbox-gl.js')

// initial state
const state = {
  myMap: {},
  mapLoaded: false
}

const mutations = {
  loadMap (state, myMap) {
    state.myMap = myMap
  }
}

const actions = {
  loadMap (context) {
    'use strict'
    mapboxgl.accessToken = 'mysecretmapboxkey'
    var myMap = new mapboxgl.Map({
      container: 'map',
      style: simple,
      hash: true,
      center: [-74.0073, 40.7124],
      zoom: 16
    })
    context.commit('loadMap', myMap)
  }
}

export default {
  state,
  mutations,
  actions
}

编辑:

鉴于您的鼠标交互导致状态发生变化，您可以computed property in you vue instance with getter and setter，如下所示：

computed: {
  myMapForView: {
    // getter
    get: function () {
      return this.$store.state. myMap
    },
    // setter
    set: function (newMap) {
      this.$store.commit('loadMap', newMap)
    }
  }
}

工作Fiddle：http://jsfiddle.net/aucqteLn/

同时检查：

如何在 Vuex 中为 mapbox 地图设置集中状态？

How to setup a centralized state for a mapbox map in Vuex?

vue.js

mapbox-gl-js

vue-component

vuex

vuejs2

工作Fiddle：http://jsfiddle.net/aucqteLn/