vue parent component changes the properties of child components

In Vue, data communication between parent and child components is a very common requirement. The parent component can pass data to the child component through props, and the child component can notify the parent component upwards about changes through events. However, in some cases, we need to change some properties of the child component in the parent component, which requires using $refs to operate the child component.

In Vue, $refs is a reference that can access variables or methods inside the child component in the parent component. Through $refs, we can get the instance of the subcomponent and call its methods or modify its properties.

Below, we use an example to see how to change the properties of a child component through the parent component.

First, we need to define a subcomponent that has an attribute name and provide a method setName for setting the value of the attribute.

<template>
  <div>
    <p>子组件的name属性为：{{ name }}</p>
  </div>
</template>

<script>
export default {
  name: 'Subcomponent',
  props: {
    name: {
      type: String,
      default: ''
    }
  },
  methods: {
    setName(value) {
      this.name = value;
    }
  }
}
</script>

Next, introduce the child component in the parent component and use the child component in the template. We also need to set the ref attribute on the child component tag to reference the child component instance in the parent component.

<template>
  <div>
    <button @click="changeName">更改子组件name属性值</button>
    <subcomponent ref="mySubcomponent" :name="name"></subcomponent>
  </div>
</template>

<script>
import Subcomponent from './Subcomponent.vue';

export default {
  name: 'ParentComponent',
  components: {
    Subcomponent
  },
  data() {
    return {
      name: 'Vue.js'
    }
  },
  methods: {
    changeName() {
      this.$refs.mySubcomponent.setName('React');
    }
  }
}
</script>

In the parent component, we define a method changeName, which obtains the instance of the subcomponent through $refs, and calls its setName method to modify the name attribute of the subcomponent to React. In this way, after clicking the button, you can see on the page that the name attribute of the subcomponent has been changed.

In the actual project development process, we often need to modify some properties of child components through parent components. At this time, $refs will become a very important tool for us. When subcomponents need to respond to certain events, we can use events to achieve this. Next, let us use a small example to further understand the mechanism of parent components changing the properties of child components.

<template>
  <div>
    <button @click="changeName">更改子组件name属性值</button>
    <subcomponent ref="mySubcomponent" :name="name" @changeName="handleChangeName"></subcomponent>
  </div>
</template>

<script>
import Subcomponent from './Subcomponent.vue';

export default {
  name: 'ParentComponent',
  components: {
    Subcomponent
  },
  data() {
    return {
      name: 'Vue.js'
    }
  },
  methods: {
    changeName() {
      this.$refs.mySubcomponent.setName('React');
    },
    handleChangeName(newName) {
      this.name = newName;
    }
  }
}
</script>

In this example, we add a @changeName event listener on the child component tag and define a handleChangeName method in the parent component to respond to the event. When $emit('changeName', newName) is called in the child component, the handleChangeName method in the parent component will be called and the new name passed in will be assigned to the name attribute. In this way, you can also see the change in the name attribute value of the subcomponent in real time on the page.

In general, in Vue, it is very convenient to obtain the instance of a subcomponent through $refs, and modify its properties or call its methods. Using events together, we can realize the function of the parent component changing the properties of the child component, bringing more possibilities to page interaction.

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