为Vuex添加同步Action

为什么要添加同步 Action？

在某些操作中，如获取内存中的数据时，需要立即返回对应的值，而 Vuex 的 Action 规定了只能返回一个 Promise，这时，如果我们想获取返回值就需要使用 then 或者 await，代码就会变得不直观，而如果触发 Mutation 再从 State 获取值也是同理，所以如何能让 Action 不是异步的又能保持和 Vuex 的 Action 拥有一样的功能呢？

添加同步 Action

首先我们先看看 Vuex 的 Action 的结构是如何的：

const actions = {
  asyncAction(context, data) {
    // do soming...
  },
};

const actions = {
  asyncAction(context, data) {
    // do soming...
  },
};

可以看到，action 中传入了 context 和 data，所以我们添加的同步 action 也需要增加这两个参数，同时将 store 绑定到 action 的 this。

const actions = {
  asyncAction(context, data) {
    // do soming...
  },
};

export const syncActions = {
  // 同时导出，以便后续的操作
  syncActin(context, data) {
    // do soming...
    return val;
  },
};

//...

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

const actions = {
  asyncAction(context, data) {
    // do soming...
  },
};

export const syncActions = {
  // 同时导出，以便后续的操作
  syncActin(context, data) {
    // do soming...
    return val;
  },
};

//...

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

在 index.js 导入对应的模块和同步 actions 对象，同时导出修改过的同步 action，用于 mapSyncActions，并为每个同步 action 绑定 this 和注入参数。

import note, { syncActions as syncNote } from "./modules/note";
import { dispatchSync } from "./syncActions";

export const syncActions = {
  note: syncNote,
};

for (const nKey in syncActions) {
  let getters = {};
  for (const gKey of Object.keys(store.getters)) {
    let k = gKey.split("/");
    if (k[0] === nKey) {
      Object.defineProperty(getters, k[1], {
        get() {
          return store.getters[gKey];
        },
      });
    }
  }
  for (const iKey in syncActions[nKey]) {
    syncActions[nKey][iKey] = syncActions[nKey][iKey].bind(store, {
      state: store.state[nKey],
      rootState: store.state,
      commit: function (type, payload = null, options = null) {
        store.commit(nKey + "/" + type, payload, options);
      }.bind(store),
      dispatch: function (type, payload = null, options = { root: false }) {
        let t = options.root ? type : nKey + "/" + type;
        return store.dispatch(t, payload);
      }.bind(store),
      dispatchSync: function (type, payload = null, options = { root: false }) {
        let t = options.root ? type : nKey + "/" + type;
        return dispatchSync(t, payload);
      }.bind(store),
      rootGetters: store.getters,
      getters: getters,
    });
  }
}

store.syncActions = syncActions;
store.dispatchSync = dispatchSync;

import note, { syncActions as syncNote } from "./modules/note";
import { dispatchSync } from "./syncActions";

export const syncActions = {
  note: syncNote,
};

for (const nKey in syncActions) {
  let getters = {};
  for (const gKey of Object.keys(store.getters)) {
    let k = gKey.split("/");
    if (k[0] === nKey) {
      Object.defineProperty(getters, k[1], {
        get() {
          return store.getters[gKey];
        },
      });
    }
  }
  for (const iKey in syncActions[nKey]) {
    syncActions[nKey][iKey] = syncActions[nKey][iKey].bind(store, {
      state: store.state[nKey],
      rootState: store.state,
      commit: function (type, payload = null, options = null) {
        store.commit(nKey + "/" + type, payload, options);
      }.bind(store),
      dispatch: function (type, payload = null, options = { root: false }) {
        let t = options.root ? type : nKey + "/" + type;
        return store.dispatch(t, payload);
      }.bind(store),
      dispatchSync: function (type, payload = null, options = { root: false }) {
        let t = options.root ? type : nKey + "/" + type;
        return dispatchSync(t, payload);
      }.bind(store),
      rootGetters: store.getters,
      getters: getters,
    });
  }
}

store.syncActions = syncActions;
store.dispatchSync = dispatchSync;

然后，我们还要实现对应的 dispatch 方法和 mapActions 方法，来实现调用该 action，在 index.js 同级文件夹下添加一个 syncActions.js

import { syncActions } from "./index";

function addMethod(object, name, fn) {
  var old = object[name];
  object[name] = function () {
    if (fn.length === arguments.length) {
      return fn.apply(this, arguments);
    } else if (typeof old === "function") {
      return old.apply(this, arguments);
    }
  };
}

const mod = {};

addMethod(mod, "mapSyncActions", (map) => {
  let fn = {};
  let namespace = "";
  let action = "";
  for (let i = 0; i < map.length; i++) {
    [namespace, action] = map[i].split("/");
    if (syncActions[namespace]) {
      fn[action] = syncActions[namespace][action];
    }
  }
  return fn;
});

addMethod(mod, "mapSyncActions", (namespace, map) => {
  let fn = {};
  for (let i = 0; i < map.length; i++) {
    if (syncActions[namespace]) {
      fn[map[i]] = syncActions[namespace][map[i]];
    }
  }
  return fn;
});

export const mapSyncActions = mod.mapSyncActions;
export function dispatchSync(type, payload = null) {
  let namespace = "";
  let action = "";
  [namespace, action] = type.split("/");
  if (syncActions[namespace]) {
    return syncActions[namespace][action](payload);
  }
}

import { syncActions } from "./index";

function addMethod(object, name, fn) {
  var old = object[name];
  object[name] = function () {
    if (fn.length === arguments.length) {
      return fn.apply(this, arguments);
    } else if (typeof old === "function") {
      return old.apply(this, arguments);
    }
  };
}

const mod = {};

addMethod(mod, "mapSyncActions", (map) => {
  let fn = {};
  let namespace = "";
  let action = "";
  for (let i = 0; i < map.length; i++) {
    [namespace, action] = map[i].split("/");
    if (syncActions[namespace]) {
      fn[action] = syncActions[namespace][action];
    }
  }
  return fn;
});

addMethod(mod, "mapSyncActions", (namespace, map) => {
  let fn = {};
  for (let i = 0; i < map.length; i++) {
    if (syncActions[namespace]) {
      fn[map[i]] = syncActions[namespace][map[i]];
    }
  }
  return fn;
});

export const mapSyncActions = mod.mapSyncActions;
export function dispatchSync(type, payload = null) {
  let namespace = "";
  let action = "";
  [namespace, action] = type.split("/");
  if (syncActions[namespace]) {
    return syncActions[namespace][action](payload);
  }
}

如果要在 Vuex 模块中使用，只需要导入 syncActions.js 然后同 Vuex 的 action 调用一样即可。

import { dispatchSync } from "../syncActions";

let info = dispatchSync("note/listOperate", {
  operate: "get",
  storage: storage,
  path: path,
});

import { dispatchSync } from "../syncActions";

let info = dispatchSync("note/listOperate", {
  operate: "get",
  storage: storage,
  path: path,
});

若要在组件中使用，只需要同 mapActions 一样使用 mapSyncActions 即可，或者使用 dispatchSync。

import { mapSyncActions } from "./store/syncActions";

export default {
  methods: {
    ...mapSyncActions("note", ["listOperate"]),
    fun() {
      this.$store.dispatchSync("note/listOperate");
    },
  },
};

import { mapSyncActions } from "./store/syncActions";

export default {
  methods: {
    ...mapSyncActions("note", ["listOperate"]),
    fun() {
      this.$store.dispatchSync("note/listOperate");
    },
  },
};

结语

说实在搞这个其实没啥用，因为用到的机会其实也很小，只是当初我把 XK-Note 重构到 Vuex 时，不想修改太多的代码逻辑搞出来的，本文的实例具体可以查看 XK-Note。

为Vuex添加同步Action

https://blog.ixk.me/post/add-sync-action-for-vuex

许可协议
BY-NC-SA
本文作者
Otstar Lin
发布于
2019/11/16

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