如何在模块命名空间中使用 Vuex 类型常量？

Question

我有这个 Vuex 模块：

//modules/things.js
const state = {
  firstThing: 'abc',
  secondThing: 'def',
};

const getters = {
  getFirstThing: state => state.firstThing,
  getSecondThing: state => state.secondThing,
};

const mutations = {
  setFirstThing: (state, payload) => state.firstThing = payload,
  setSecondThing: (state, payload) => state.secondThing = payload
};

const actions = {};

export default {
  namespaced: true,   // <------
  state,
  mutations,
  actions,
  getters
};

我使用namespaced: true flag 并且可以像这样使用这个模块：

this.$store.state.things.firstThing             // <-- return abc here
this.$store.commit('things/setFirstThing', 10)
this.$store.getters['things/getFirstThing']     // <-- return abc here

如果我将使用像 Vuex 中的 official example 这样的常量，并像这样重构我的 modules/things.js 文件：

export const Types = {
  getters: {
    GET_FIRST_THING: 'GET_FIRST_THING',
    GET_SECOND_THING: 'GET_SECOND_THING',
  },
  mutations: {
    SET_FIRST_THING: 'SET_FIRST_THING',
    SET_SECOND_THING: 'SET_SECOND_THING',
  }
};

const getters = {
  [Types.getters.GET_FIRST_THING]: state => state.firstThing,
  [Types.getters.GET_SECOND_THING]: state => state.secondThing,
};

const mutations = {
  [Types.mutations.SET_FIRST_THING]: (state, payload) => state.firstThing = payload,
  [Types.mutations.SET_SECOND_THING]: (state, payload) => state.secondThing = payload
};

我将不得不使用命名空间前缀：

this.$store.commit('things/' + Types.mutations.SET_FIRST_THING, 10);
this.$store.getters['things/' +  + Types.getters.GET_FIRST_THING]  

如果我将模块命名空间前缀包含到 Types 常量中，我将不得不使用字符串前缀 things/ 来声明突变/动作/getters：

const getters = {
  ['things/' + Types.getters.GET_FIRST_THING]: state => state.firstThing,
  ['things/' + Types.getters.GET_SECOND_THING]: state => state.secondThing,
};

如何避免？

Answer 1

来自@hedin 的The answer 为我工作出色，谢谢！

我遇到的唯一问题是：

1. 我正在使用 Typescript。

2. 这可能有点过于冗长，影响可读性。但是类型安全对我来说更重要，我愿意容忍一些冗长的类型检查。

受他的设计启发，我对其进行了打字并减少了冗长。

（我正在使用 Vue 3（带有组合 API）+ Vuex 4（带有命名空间模块）。）

首先，我创建了如下所示的namespace-helper.ts：

import _ from "lodash";

type NamespaceHelper = {
  [name: string]: string;
};

// Enhanced from @hedin, see https://stackoverflow.com/a/47646215/1360592
export default (
  namespace: string,
  types: any,
  section: "getters" | "actions" | "mutations",
): NamespaceHelper => {
  return _.reduce(
    types,
    (typeObj: NamespaceHelper, typeValue, typeName) => {
      if (typeName === section) {
        return _.reduce(
          typeValue,
          (obj: NamespaceHelper, v, k) => {
            obj[k] = v.replace(namespace, "");
            return obj;
          },
          {},
        );
      }
      return typeObj;
    },
    {},
  );
};

然后在我的商店模块中，我有：

const namespace = "things";

// For external use
export const Types = {
  getters: {
    GET_FIRST_THING: `${namespace}/GET_FIRST_THING`,
    GET_SECOND_THING: `${namespace}/GET_SECOND_THING`,
  },
  actions: {
    DO_FIRST_THING: `${namespace}/DO_FIRST_THING`,
    DO_SECOND_THING: `${namespace}/DO_SECOND_THING`,
  },
  mutations: {
    SET_FIRST_THING: `${namespace}/SET_FIRST_THING`,
    SET_SECOND_THING: `${namespace}/SET_SECOND_THING`,
  },
};

// For internal use in the same store
const _getters = removeNamespace(`${namespace}/`, Types, "getters");
const _actions = removeNamespace(`${namespace}/`, Types, "actions");
const _mutations = removeNamespace(`${namespace}/`, Types, "mutations");

// getters
const getters: GetterTree<MyStoreState, RootState> = {
  [_getters. GET_FIRST_THING]: (state) => {
    return state.blah;
  },
  ...
};

// actions
const actions: ActionTree<MyStoreState, RootState> = {
  [_actions.DO_FIRST_THING]: ({ commit }) => {
    // do stuff here
    ...
    commit(_mutations.SET_FIRST_THING);
  },
};

// mutations
const mutations = {
  [_mutations.SET_FIRST_THING]: (state: MyStoreState) => {
    state.blah = "foo";
  },
};

export default {
  namespaced: true,
  state,
  getters,
  actions,
  mutations,
};

这是我从组件中使用它的方式：

<script lang="ts">
// imports go here, not shown for brevity

import { Types } from "@/store/modules/things";

export default defineComponent({
  name: "Thing",
  setup(props) {
    const store = useStore<RootState>();

    // I prefer singular for consuming getters and actions externally.
    const { getters: getter, actions: action } = Types;

    const firstThing = computed<ThingType>(() =>
      store.getters[getter.GET_FIRST_THING],
    );

    store.dispatch(action.DO_FIRST_THING);

    return {
      firstThing,
    };
  },
});
</script>

Answer 2

您可以通过namespaced: false 禁用命名空间，只使用带前缀的常量：

export const Types = {
  getters: {
    GET_FIRST_THING: 'THINGS_GET_FIRST_THING',    // your namespace without '/' slash
    GET_SECOND_THING: 'THINGS_GET_SECOND_THING',
  },
  // ...
}

-它会起作用的。

但是如果您仍然想在模块中保留namespaced: true 并使用常量，您可以定义两种类型的常量：public 和 private：

export const Types = {                                               // <-- public
  getters: {
    GET_FIRST_THING: 'things/GET_FIRST_THING',
    GET_SECOND_THING: 'things/GET_SECOND_THING',
  },
  mutations: {
    SET_FIRST_THING: 'things/SET_FIRST_THING',
    SET_SECOND_THING: 'things/SET_SECOND_THING',
  }
};

const _types = removeNamespace('things/', Types);                    // <-- private

然后只在 Vuex 模块中使用私有 _types：

const getters = {
  [_types.getters.GET_FIRST_THING]: state => state.firstThing,       
  [_types.getters.GET_SECOND_THING]: state => state.secondThing,
};

//...

和公开Types模块外：

// some-component.vue
this.$store.commit(Types.mutations.SET_FIRST_THING, 10);
this.$store.getters[Types.getters.GET_FIRST_THING]
// ...

还在新的namespace-helper.js 文件中实现简单的removeNamespace 函数：

export default function removeNamespace(namespace, types){
  return _.reduce(types, (typeObj, typeValue, typeName) => {
    typeObj[typeName] = _.reduce(typeValue, (obj, v, k)=>{
      obj[k] = v.replace(namespace, '');
      return obj;
    }, {});
    return typeObj;
  }, {});
}