解决Vue 给mapState中定义的属性赋值报错的问题

网络编程 2024/12/23 佚名

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1. 实践环境

2. 问题描述

<script>
import { mapState } from 'vuex';
export default {
 name: "displayCount",
 computed: {
  ...mapState({
   ...略
   count: state => state.a.count
  })
 },
 methods: {
  increaseCount () {
   this.count = this.count + 1
  }
 }
};
</script>
<style>
</style>

如上，我们希望在执行increaseCount函数时，给mapstate函数中映射定义的this.count赋值，给该值增加1，结果，提示

[Vue warn]: Computed property "count" was assigned to but it has no setter.

3. 解决方案1

如下，把属性“移出mapState”，然后为属性新增get，set方法，分别用于获取值和改变值（按store状态管理规定的方式）

<script>
import { mapState } from 'vuex';
export default {
 name: "displayCount",
 computed: {
  ...mapState({
...略
  }),
  count: {
   get() {
    return this.$store.state.a.count;
   },
   set(val) {
    this.$store.commit("increaseCount", val);
   }
  }
 },
 methods: {
  increaseCount () {
   this.count = this.count + 1
  }
 }
};
</script>

注意：this.$store.commit("increaseCount", val);中的increaseCount方法名称，并不是methods中定义的方法名称，而是store中定义的方法

4. 解决方案2

通过对比当前属性值和store状态值，然后根据比较结果，决定是否根据store状态管理规则更新状态值。

<script>
import { mapState } from 'vuex';
export default {
 name: "displayCount",
 computed: {
  ...mapState({
   count: state => state.a.count
  })
 },
 methods: {
  increaseCount () {
   if (this.count == this.$store.state.a.count) {
    this.$store.commit("increaseCount", this.count+1);
   }
  }
 }
};
</script>

总结

vue给mapState属性赋值,vue,mapState赋值