Vue 給mapState中定義的屬性賦值報錯的解決方案
by:授客 QQ：1033553122
1. 實踐環境
Vue 2.9.6
2. 問題描述
<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，我們希望在執行increaseCount函數時，給mapstate函數中映射定義的this.count賦值，給該值增加1，結果，提示
[Vue warn]: Computed property "count" was assigned to but it has no setter.
3. 解決方案1
如下，把屬性“移出mapState”，然后為屬性新增get，set方法，分別用於獲取值和改變值（按store狀態管理規定的方式）
<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.$store.commit("increaseCount", val);中的increaseCount方法名稱，並不是methods中定義的方法名稱，而是store中定義的方法
4. 解決方案2
通過對比當前屬性值和store狀態值，然后根據比較結果，決定是否根據store狀態管理規則更新狀態值。
<script>
import { mapState } from 'vuex';
export default {
name: "displayCount",
computed: {
...mapState({
count: state => state.a.count
})
},
methods: {
increaseCount () {
if (this.count == this.$store.state.a.count) {
this.$store.commit("increaseCount", this.count+1);
}
}
}
};
</script>