Vuex中通过Axios初始化状态后mapGetters返回undefined问题求助

我正在学习Vue 2和Vuex，测试通过Axios从API初始化状态。流程是：初始状态为空对象，组件beforeMount钩子触发initState action，再通过startState mutation把状态更新为API返回的数据。但mapGetters返回undefined，页面加载不出数据。Vue Devtools显示状态已经更新成功，附上代码和截图，求解决思路。

代码片段 #

TodoModule.js #

import axios from "axios";

const state = {};

const getters = {
    allTodos: state => state.todos
};

const actions = {
    async initState({commit}) {
        await axios.get(`https://mockapi.io/api/todo/v1/endpoint`)
        .then((res) => {commit('startState', res.data)})
        .catch((err) => console.log(err))
    }
};

const mutations = {
    startState: (state, payload) => state.todos = payload
};

export default {
    state,
    getters,
    actions,
    mutations
}

Store(Index.js) #

import Vuex from 'vuex';
import Vue from 'vue';
import TodoModule from './modules/TodoModule.js';

// Load vuex
Vue.use(Vuex);

// Create store
export default new Vuex.Store({
    modules: {
        TodoModule
    }
});

TodoApp.vue #

<template>
  <div>
    <h3>Vuex Todo App</h3>
    <div class="todos">
      <div class="todo" v-for="todo in allTodos" :key="todo.id">
        {{ todo.name }}
      </div>
    </div>
  </div>
</template>

<script>
import { mapGetters} from 'vuex';

export default {
  name: "TodoApp",
  beforeMount(){
    this.$store.dispatch("initState");
  },
  computed: {
    ...mapGetters(["allTodos"])
  }
};
</script>

<style>
</style>

App.vue #

<template>
  <div id="app">
    <!-- <img alt="Vue logo" src="./assets/logo.png"> -->
    <!-- <HelloWorld msg="Welcome to Your Vue.js App"/> -->
    <TodoApp />
  </div>
</template>

<script>
// import HelloWorld from './components/HelloWorld.vue'
import TodoApp from './components/TodoApp.vue';

export default {
  name: 'App',
  components: {
    // HelloWorld,
    TodoApp
}
}
</script>
  body {
    font-family: "Franklin Gothic Medium", "Arial Narrow", Arial, sans-serif;
    line-height: 1.6;
    background: #e8f7f0;
  }
  .container {
    max-width: 1100px;
    margin: auto;
    overflow: auto;
    padding: 0 2rem;
  }
<style>
#app {
  font-family: Avenir, Helvetica, Arial, sans-serif;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-align: center;
  color: #2c3e50;
  margin-top: 60px;
}
</style>

Vue Devtools状态截图 #

问题核心是Vuex模块的命名空间未启用，导致mapGetters无法正确定位到模块内的allTodos getter。

修复步骤： #

1. 在TodoModule.js中开启命名空间：

export default {
    namespaced: true, // 添加这一行启用命名空间
    state,
    getters,
    actions,
    mutations
}

2. 在TodoApp.vue中调整mapGetters，指定所属模块：

computed: {
  ...mapGetters("TodoModule", ["allTodos"])
}

3. 触发action时也要加上模块前缀：

beforeMount(){
  this.$store.dispatch("TodoModule/initState");
}

额外优化建议： #

• 初始状态提前声明todos为空数组，避免首次渲染时allTodos为undefined导致v-for报错：

const state = {
  todos: []
};

• 统一async/await写法，避免混用.then/.catch：

async initState({commit}) {
  try {
    const res = await axios.get(`https://mockapi.io/api/todo/v1/endpoint`);
    commit('startState', res.data);
  } catch (err) {
    console.log(err);
  }
}

内容的提问来源于stack exchange，提问作者Zero Gear