访问子 vue 组件数据函数中的道具？

Question

我有下面的子组件。道具从父级中的输入选择器更新。为什么 level： this.globalForm.level 不更新孩子的 level

家长：

<template>
  <div>
    <div class="form-container">
      <select class="form-control" v-model="level">
        <option v-for="level in options" v-bind:key="level">{{ level }}</option>
      </select>
      <button @click="submit()">Create</button>
    </div>
    <child v-bind:globalForm="globalForm"/>
  </div>
</template>

    <script>
inputFiled;
export default {
  data() {
    return {
      level: "",
      globalForm: {
        level: ""
      },
      options: ["level1", "level2", "level3"]
    };
  },
  components: {
    child
  },
  methods: {
    submit() {
      this.globalForm.level = this.level;
    }
  },
  watch: {
    level() {
      this.globalForm.level = this.level;
    }
  }
};
</script>

孩子：

<template>
  <div class="form-container">
      <option v-for="level in options" v-bind:key="level">{{ level }}</option>
  </div>
</template>

<script>
export default {
  props: { globalForm: Object },
  data() {
    return {
      options: ["level1","level2","level3",],
      level: this.globalForm.level //this does not update the child's level component
    };
  }
};
</script>

Answer 1

TLDR

level 应该是子项上的计算属性，以便您可以检测 prop 中的变化。您正在数据函数中设置级别，因此对 prop 的更新永远不会达到级别。

下面你会找到一个我认为你想要实现的最简单的例子。

Vue.config.productionTip = false;
Vue.component('parent', {
  template: `
  <div class="parent">
    <b>PARENT</b>
    <div class="form-container">
      <select class="form-control" v-model="level">
        <option v-for="level in options" v-bind:key="level">{{ level }}</option>
      </select>
      <button @click="submit()">Create</button>
    </div>
    <child v-bind:globalForm="globalForm"/>
  </div>
  `,
  data: () => ({
    level: "",
    globalForm: {
      level: ""
    },
    options: ["level1", "level2", "level3"]
  }),
  methods: {
    submit() {
      this.globalForm.level = this.level;
    }
  }
});

Vue.component('child', {
  template: `
  <div class="form-container child">
      <p><b>Child</b></p>
      Level: {{ level }}
  </div>
  `,
  props: {
    globalForm: Object
  },
  computed: {
    level() {
      return  this.globalForm.level;
    }
  }
});

new Vue({
  el: "#app"
})

.parent {
  background-color: darkgray;
  padding: .5em;
  border: solid 1px black;
}
.child {
  background-color: lightgray;
  padding: .5em;
  border: solid 1px black;
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/vue/2.5.17/vue.js"></script>
<div id="app">
  <parent></parent>
</div>