day09-vuex进阶

1.this.$store.commit()
2.mapState
3.mapActions
4.mapMutations
5.getters,mapGetters
6.modules

一、this.$store.commit()

直接派发一个事件给mutations

export default {
  name: 'home',
  methods:{
    handleClick(){
      this.$store.commit("changeCity")
    }
  }
}
mutations:{
    changeCity(state){
        state.city="成都"
    }
}

二、mapState

Tips:如何有多个状态需要获取,使用这个辅助函数效率更高

//store.js
export default new Vuex.Store({
  state: {
    city:"武汉",
    name:"程超",
    age:20,
    sex:"男"
  } 
})

<template>
  <div class="home">
    <h2 >{{city}}</h2>
    <h2 >{{age}}</h2>
  </div>
</template>

<script>
import {mapState} from 'vuex';
export default {
  name: 'home',
  computed:{
    ...mapState(['city','name','age','sex'])
  }
}
</script>

三、mapActions

映射actions中的事件

export default new Vuex.Store({
  state: {
    count:0
  },
  /* 异步操作,处理一些复杂的业务逻辑 */
  actions: {
    increase(ctx){
      ctx.commit("myIncrease")
    },
    decrease(ctx){
      ctx.commit("myDecrease")
    }
  },
  /* 简单的更改状态(state)的逻辑*/
  mutations: {
     myIncrease(state){
       state.count+=1;
     },
     myDecrease(state){
       state.count-=1;
     }
  },

})

<template>
  <div class="home">
    <h2>{{this.$store.state.count}}</h2>
    <button @click="increase">增加</button>
    <button @click="decrease">减少</button>
  </div>
</template>

<script>
import {mapActions} from 'vuex';
export default {
  name: 'home',
  methods:{
    ...mapActions(['increase','decrease']),   
  }
}
</script>

四、mapMutations

<template>
  <div class="home">
    <h2>{{this.$store.state.count}}</h2>
    <button @click="myIncrease">增加</button>
    <button @click="myDecrease">减少</button>
  </div>
</template>

<script>
import {mapMutations} from 'vuex';
export default {
  name: 'home',
  methods:{
     ...mapMutations(['myIncrease','myDecrease']) 
  }
}
</script>

五、getters,mapGetters

/* 对state中的数据进行再次处理 */
  getters:{
    myCount(state){
      return "当前的数量:"+state.count;
    }
}

//mapGetters 将 store 中的 getter 映射到局部计算属性
import {mapGetters} from 'vuex';
export default {
  name: 'home',
  computed:{
    ...mapGetters(['myCount'])
  }
}

六、modules

作用:当store对象非常复杂的时候,我们可以根据将其拆分成不同的模块

6-1 新建modules文件夹,拆分module

//user.js
const user = {
    state: {
        name:"程超"
    },
    mutations:{},
    actions: { },
    getters: { }
}
export default user;

//info.js
const info = {
    state: {
        tips:12,
        news:15
    },
    mutations: {
        add(state){
            state.tips++;
        },
        reduce(state){
            state.tips--;
        }
    },
    actions: { },
    getters: { }
}
export default info;

//index.js
export default new Vuex.Store({
  modules:{
    user,
    info
  }
})

6-2 使用数据

<template>
  <div class="home">
    <h2>首页</h2>
    <h3>{{tips}}</h3>
    <h4>{{news}}</h4>
    <h5>{{name}}</h5>
    <button @click="add">增加</button>
    <button @click="reduce">减少</button>
  </div>
</template>

<script>
import { mapState,mapMutations } from "vuex";
export default {
  name: "home",
  computed: {
    ...mapState({
      tips: state => state.info.tips,
      news: state => state.info.news,
      name: state => state.user.name
    })
  },
  methods:{
    ...mapMutations(['add','reduce'])
  }
};
</script>