Vue 给mapState中定义的属性赋值报错的解决方案
1. 实践环境
Vue 2.9.6
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>
