vue2.0中使用mapState及mapActions的方式
// 使用mapState
computed: {
...mapState({
//...
})
}
methods: {
...mapActions(['fnA', 'fnB'])
}vue3.0中获取state和使用actions的方式
import {computed} from 'vue'
import {useStore} from 'vuex'
setup() {
const store = useStore();
const stateA = computed(() => store.state.stateA);
const stateB = computed(() => store.state.stateB);
const methodA = store.dispatch('methodA', {name: '张三'});
}如何才能在vue3下使用mapState这些api呢？
答案是封装mapState，mapGetters，mapActions方法。
1、新建useMapper.js
import { useStore } from 'vuex'
import { computed } from 'vue'
export function useStateMapper(mapper, mapFn) {
const store = useStore();
const storeStateFns = mapFn(mapper);
const storeState = {};
Object.keys(storeStateFns).forEach(fnKey => {
// vuex源码中mapState和mapGetters的方法中使用的是this.$store,所以更改this绑定
const fn = storeStateFns[fnKey].bind({ $store: store });
storeState[fnKey] = computed(fn)
})
return storeState
}
export function useActionMapper(mapper, mapFn) {
const store = useStore();
const storeActionsFns = mapFn(mapper);
const storeAction = {};
Object.keys(storeActionsFns).forEach(fnKey => {
storeAction[fnKey] = storeActionsFns[fnKey].bind({ $store: store })
})
return storeAction
}2、新建useState.js
import { mapState, createNamespacedHelpers } from 'vuex'
import { useStateMapper } from './useMapper'
import {checkType} from './index'
export function useState(moduleName, mapper) {
let mapperFn = mapState;
// 如果使用模块化，则使用vuex提供的createNamespacedHelpers方法找到对应模块的mapState方法
if (checkType(moduleName) === "[object String]" && moduleName.length > 0) {
mapperFn = createNamespacedHelpers(moduleName).mapState
}
return useStateMapper(mapper, mapperFn)
}3、新建useGetters.js
import { mapGetters, createNamespacedHelpers } from 'vuex'
import { useStateMapper } from './useMapper'
import {checkType} from './index'
export function useGetters(moduleName, mapper) {
let mapperFn = mapGetters;
// 如果使用模块化，则使用vuex提供的createNamespacedHelpers方法找到对应模块的mapGetters方法
if (checkType(moduleName) === "[object String]" && moduleName.length > 0) {
mapperFn = createNamespacedHelpers(moduleName).mapGetters
}
return useStateMapper(mapper, mapperFn)
}4、新建useActions.js
import { mapActions, createNamespacedHelpers } from 'vuex';
import {useActionMapper} from './useMapper'
import {checkType} from './index'
export function useActions(moduleName, mapper) {
let mapperFn = mapActions;
// 如果使用模块化，则使用vuex提供的createNamespacedHelpers方法找到对应模块的mapActions方法
if (checkType(moduleName) === "[object String]" && moduleName.length > 0) {
mapperFn = createNamespacedHelpers(moduleName).mapActions
}
return useActionMapper(mapper, mapperFn)
}5、页面中使用
<template>
<div class="home">
<span>姓名：{{name}} 年龄：{{age}} 性别：{{sex}}</span>
<button @click="changeName">改名</button>
</div>
</template><script>
// @ is an alias to /src
import {useState} from '@/utils/useState'
import {useActions} from '@/utils/useAction'
export default {
name: "home",
setup() {
const storeState = useState('home', ['name', 'age', 'sex'])
const storeActions = useActions('home', ['setName'])
const changeName = () => {
storeAction.setName('李四')
}
return {
changeName,
...storeState,
...storeActions
};
},
};
</script>vue3对vuex中mapState,mapGetters辅助函数封装
1. readonly API的使用
在我们传递给其他组件数据时，如果直接将响应式数据传递给子组件。子组件如果使用数据不规范，修改了父组件传进来的props值没有任何反馈。
// 父组件
// <ReadonlyChild :info="info" />
setup() {
const info = reactive({
name: "哇哈哈",
});
return {
info,
};
}
// 子组件
setup(props) {
const onChangeInfo = () => {
const info = props.info;
// 修改父组件传来的props 没有任何反馈。
info.name = "woowow";
};
return {
onChangeInfo,
};
}开发中我们往往希望其他组件使用我们传递的内容，但是不允许它们修改时，就可以使用 readonly了。
// 父组件
// <ReadonlyChild :info="infoReadonly" />
setup() {
const info = reactive({
name: "哇哈哈",
});
const infoReadonly = readonly(info);
const onChangeInfo = () => {
// 在父组件中可修改info中的值，子组件依然可响应更新
info.name = "父组件给你的值";
};
return {
infoReadonly,
onChangeInfo
};
}
// 子组件
setup(props) {
const onChangeInfo = () => {
const info = props.info;
// 此时修改props时，控制台会有一个警告：
// Set operation on key "name" failed: target is readonly.
info.name = "woowow";
};
return {
onChangeInfo,
};
}2. 响应式变量直接解构会失去响应性
将响应式变量直接解构会失去其响应性
const info = reactive({ age: 18 });
// 直接解构后 age 值失去响应性，当 onChangeAge 函数触发时，age值不在变，而ageRef 依然具有响应性
const { age } = info;
const { age: ageRef } = toRefs(info);
const onChangeAge = () => {
info.age++;
};3. watchEffect 清除副作用
watchEffect API 可自动收集依赖项，当依赖项改变时触发侦听器函数。当我们在侦听器函数执行额外的副作用函数，例如：发送网络请求时。每当依赖性项变更都会发起一个新的网络请求，那么上一次的网络请求应该被取消掉。这个时候我们就可以清除上一次的副作用了。
setup() {
const count = ref(0);
const onChangeCount = () => {
count.value++;
};
watchEffect((onInvalidate) => {
// 侦听器函数中需要发起网络请求，用setTimeout模拟
const timer = setTimeout(() => {
console.log("请求成功啦");
}, 2000);
// 在侦听器函数重新执行时触发onInvalidate函数
onInvalidate(() => {
// 在这个函数中清除请求
clearTimeout(timer);
console.log("onInvalidate 回调触发");
});
// 自动收集count的依赖
console.log("count-在改变", count.value);
});
return {
count,
onChangeCount,
};
}4. setup 函数访问Vuex中Store数据
4.1 使用mapState辅助函数
通常需要通computed函数来获取state中数据，并保存响应性。
setup() {
const store = useStore();
// 在setup中要获取store中的state。如果state非常多，无疑这样做很繁琐
const uName = computed(() => store.state.name);
const uAge = computed(() => store.state.age);
const uHeight = computed(() => store.state.height);
const storeState = mapState(["name", "age", "height"]);
// 需要对返回值进行处理
const resStoreState = {};
Object.keys(storeState).forEach((fnKey) => {
const fn = storeState[fnKey].bind({ $store: store });
resStoreState[fnKey] = computed(fn);
});
return {
uName,
uAge,
uHeight,
...resStoreState,
};
}封装成hooks如下：
// useState.js
import { computed } from "vue";
import { useStore, mapState } from "vuex";
export default function useState(mapper) {
const store = useStore();
const storeStateFns = mapState(mapper);
const storeState = {};
Object.keys(storeStateFns).forEach((fnKey) => {
const fn = storeStateFns[fnKey].bind({ $store: store });
storeState[fnKey] = computed(fn);
});
return storeState;
}在组件中使用时
import useState from "@/hooks/useState";
setup() {
// 数组用法
const state = useState(["name", "age", "height"]);
// 对象用法，可使用别名
const stateObj = useState({
uName: (state) => state.name,
uAge: (state) => state.age,
uHeight: (state) => state.height,
});
return {
...state,
...stateObj,
};
}4.2 mapGetters 辅助函数的封装
其原理与mapState 函数封装类似
// useGetters.js
import { computed } from "vue";
import { mapGetters, useStore } from "vuex";
export default function useGetters(mapper: any) {
const store = useStore();
const storeGettersFns = mapGetters(mapper);
const storeGetters = {};
Object.keys(storeGettersFns).forEach((fnKey) => {
const fn = storeGettersFns[fnKey].bind({ $store: store });
storeGetters[fnKey] = computed(fn);
});
return storeGetters;
}useState和useGetters两个函数相似度很高，在进一下封装
// useMapper.js
import { computed } from "vue";
import { useStore } from "vuex";
export default function useMapper(mapper, mapFn) {
const store = useStore();
const storeStateFns = mapFn(mapper);
const storeState = {};
Object.keys(storeStateFns).forEach((fnKey) => {
const fn = storeStateFns[fnKey].bind({ $store: store });
storeState[fnKey] = computed(fn);
});
return storeState;
}
// useState.js
import { mapState } from "vuex";
import useMapper from "./useMapper";
export default function useState(mapper) {
return useMapper(mapper, mapState);
}
// useGetters.js
import { mapGetters } from "vuex";
import useMapper from "./useMapper";
export default function useGetters(mapper: any) {
return useMapper(mapper, mapGetters);
}4.3 对module的支持
useState 和 useGetters 函数暂时还不支持传入命名空间，进一步封装。 useMapper的封装保持不变。
// useState.js
import { createNamespacedHelpers, mapState } from "vuex";
import useMapper from "./useMapper";
export default function useState(mapper, moduleName) {
let mapperFn = mapState;
if (typeof moduleName === "string" && moduleName.length > 0) {
mapperFn = createNamespacedHelpers(moduleName).mapState;
}
return useMapper(mapper, mapperFn);
}
// useGetters.js
import { createNamespacedHelpers, mapGetters } from "vuex";
import useMapper from "./useMapper";
export default function useGetters(mapper, moduleName) {
let mapperFn = mapGetters;
if (typeof moduleName === "string" && moduleName.length > 0) {
mapperFn = createNamespacedHelpers(moduleName).mapGetters;
}
return useMapper(mapper, mapperFn);
}
// 在组件中的使用
// Home.vue
setup() {
const state = useState(["homeCounter"], "home");
const stateGetter = useGetters(["doubleHomeCounter"], "home");
return {
...state,
...stateGetter,
}
}以上为个人经验，希望能给大家一个参考，也希望大家多多支持编程网。
