如何从父级更新vuejs组件

Question

我有点迷失在 VueJs 中，我尝试用组件和 Vue 更新数据来制作一个 vue。

我了解如何使用 $emit 更新父值。

如果可以的话，谁能给我打电话

Html代码

<div id="app2" v-cloak>
  <p>{{labels.lbl1}}: {{values.value}}</p>
  how direct set {{labels.lbl1}} here: <input type="text" v-model:value="values.value"> can set the child value?
  <hr/>
  <child2 v-model:value="values.value" v-bind:lbl="labels.lbl1"></child2>
</div>

<template id="child2">
  <div>
     Set {{internallbl1}} in child:
     <input type="text" v-model="internalValue" >
     <p>Value : {{value}}</p>
  </div>
</template>

JS代码：

Vue.component('child2', {
  template: '#child2',

  //The child has a prop named 'value'. v-model will automatically bind to this prop
  props: ['value','lbl'],
  data: function() {
    return {
      internalValue: '',
      internallbl1:''
    }
  },
  watch: {
    'internalValue': function() {
      // When the internal value changes, we $emit an event. Because this event is 
      // named 'input', v-model will automatically update the parent value
      this.$emit('input', this.internalValue);
    }
  },
  created: function() {
    // We initially sync the internalValue with the value passed in by the parent
    this.internalValue = this.value;
    this.internallbl1 = this.lbl;
  }
});
new Vue({
  el: '#app2',
  data: {
    labels : {lbl1:'Parent value 1'},
    values : {value: 'hello'},
  }
});

这是 jsFiddle：https://jsfiddle.net/davidhequet/ag0thqar/5/

谢谢，大卫

Answer 1

据我了解，internalValue 在父项中的值发生变化时不会发生变化。您可以在 value 上设置观察者，每当它发生变化时，设置 internalValue，如下所示：

Vue.component('child2', {
  template: '#child2',
  ...
  ...
  ...
  created: function() {
    // We initially sync the internalValue with the value passed in by the parent
    this.internalValue = this.value;
    this.internallbl1 = this.lbl;
  },
  watch: {
    'internalValue': function() {
      // When the internal value changes, we $emit an event. Because this event is 
      // named 'input', v-model will automatically update the parent value
      this.$emit('input', this.internalValue);
    },    
     value: function(newVal) {
        this.internalValue = newVal
     }
  },
});

查看工作 fiddle。

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