在孩子身上

 <input
            type="number"
            class="form-control"
            id="phoneNumber"
            placeholder
            v-model="contact_number"
            v-on:input="(event) => this.$emit('phoneNumber', event.target.value)"
    />

data(){
    return {
      contact_number : this.contact_number_props
    }
  },
  props : ['contact_number_props']

在父

<contact-component v-on:phoneNumber="eventPhoneNumber" :contact_number_props="contact_number"></contact-component>


 methods : {
     eventPhoneNumber (value) {
      this.contact_number = value
    }

我不知道为什么，但我刚刚成功地更新了使用数据作为对象的父数据，:set & computed

Parent.vue

<!-- check inventory status - component -->
    <CheckInventory :inventory="inventory"></CheckInventory>

data() {
            return {
                inventory: {
                    status: null
                },
            }
        },

Child.vue

<div :set="checkInventory">

props: ['inventory'],

computed: {
            checkInventory() {

                this.inventory.status = "Out of stock";
                return this.inventory.status;

            },
        }

在孩子身上

 <input
            type="number"
            class="form-control"
            id="phoneNumber"
            placeholder
            v-model="contact_number"
            v-on:input="(event) => this.$emit('phoneNumber', event.target.value)"
    />

data(){
    return {
      contact_number : this.contact_number_props
    }
  },
  props : ['contact_number_props']

在父

<contact-component v-on:phoneNumber="eventPhoneNumber" :contact_number_props="contact_number"></contact-component>


 methods : {
     eventPhoneNumber (value) {
      this.contact_number = value
    }

在子组件中:

this.$emit('eventname', this.variable)

在父组件中:

<component @eventname="updateparent"></component>

methods: {
    updateparent(variable) {
        this.parentvariable = variable
    }
}

从文档中可以看到:

在Vue.js中，父子组件关系可以概括为向下的道具，向上的事件。父进程通过道具向下传递数据给子进程，子进程通过事件向父进程发送消息。接下来让我们看看它们是如何工作的。

如何传递道具

下面是将道具传递给子元素的代码:

<div>
  <input v-model="parentMsg">
  <br>
  <child v-bind:my-message="parentMsg"></child>
</div>

如何触发事件

HTML:

<div id="counter-event-example">
  <p>{{ total }}</p>
  <button-counter v-on:increment="incrementTotal"></button-counter>
  <button-counter v-on:increment="incrementTotal"></button-counter>
</div>

JS:

Vue.component('button-counter', {
  template: '<button v-on:click="increment">{{ counter }}</button>',
  data: function () {
    return {
      counter: 0
    }
  },
  methods: {
    increment: function () {
      this.counter += 1
      this.$emit('increment')
    }
  },
})
new Vue({
  el: '#counter-event-example',
  data: {
    total: 0
  },
  methods: {
    incrementTotal: function () {
      this.total += 1
    }
  }
})

There is another way of communicating data change from child to parent which uses provide-inject method. Parent component "provides" data or method for the child component, and this data or method is then "injected" into child component - but it can also be used for triggering a method in parent and passing it a parameter. This approach can be especially useful when having a child component which happens to be embedded in multiple other components. Also, in a large project care must be taken not to lose overview of provide and inject usage.

父组件App.vue使用provider访问它的方法updateParentValue(如果提供了方法而不是数据，则以方法的形式提供)的例子:

<template>
  <h2>App.vue, parentValue is: <em>{{ parentValue }}</em></h2>
  <ChildComponent1 />
</template>

<script>
import ChildComponent1 from "./components/ChildComponent1.vue";

export default {
  data() {
    return {
      parentValue: "",
    };
  },
  components: {
    ChildComponent1,
  },
  provide() {
    return {
      updateParent: this.updateParentValue,
    };
  },
  methods: {
    updateParentValue($value) {
      this.parentValue = $value;
    },
  },
};
</script>

在本例中，组件Component4。vue在“底层”，也就是说，App.vue包含了Component1, Component1包含了Component2…直到Component4，它实际上使用inject来访问父方法，然后调用父方法并传递参数$value(这里只是一个随机数):

<template>
  <div>
    <h2>ChildComponent4.vue</h2>
    <button @click="updateParent(Math.random())">
      Update parent value in App.vue
    </button>
  </div>
</template>

<script>
export default {
  inject: ["updateParent"],
};
</script>

完整的例子可以在这里找到。 Vue.js文档