Vue component communication: use provide/inject for cross-level component communication

Vue component communication: Use provide/inject for cross-level component communication

In Vue, communication between components is very important. Normally, we can use props and $emit to implement communication between parent and child components. But when the component hierarchy becomes deeper, this method becomes more cumbersome. Vue provides two options, provide and inject, for implementing cross-level component communication. This article will introduce the use of provide and inject and give some code examples.

1. Basic usage of provide and inject

In the parent component, use the provide option to define the data or methods that need to be provided to the child component. These data and methods will be injected into subcomponents through the inject option.

// Parent.vue
<template>
  <div>
    <child-component></child-component>
  </div>
</template>

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

export default {
  components: {
    ChildComponent
  },
  provide() {
    return {
      // 提供message数据给子组件使用
      message: 'Hello from parent!'
    }
  }
}
</script>

In the child component, use the inject option to receive the data or methods provided by the parent component.

// ChildComponent.vue
<template>
  <div>
    <grand-child-component></grand-child-component>
  </div>
</template>

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

export default {
  components: {
    GrandChildComponent
  },
  inject: ['message'] // 注入父组件提供的message数据
}
</script>

In the grandson component, we can directly use the data passed from the parent component.

// GrandChildComponent.vue
<template>
  <div>
    <p>{{ message }}</p>
  </div>
</template>

<script>
export default {
  inject: ['message'] // 注入父组件提供的message数据
}
</script>

2. Dynamic updates of provide and inject

provide and inject can not only provide static data, but also provide dynamic data. This means that when the data provided by provider changes, the data injected by inject will also be updated. An example of dynamic update is given below.

// Parent.vue
<template>
  <div>
    <button @click="updateMessage">Update Message</button>
    <child-component></child-component>
  </div>
</template>

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

export default {
  components: {
    ChildComponent
  },
  provide() {
    return {
      message: this.message
    }
  },
  data() {
    return {
      message: 'Hello from parent!'
    }
  },
  methods: {
    updateMessage() {
      this.message = 'Updated message from parent!';
    }
  }
}
</script>

In the above example, when the button is clicked to update the message data, all components that have this data injected will get the latest value.

3. Alternatives to provide and inject

Although provide and inject are very useful in some scenarios, in some special cases, we may need to consider other component communication Schemes such as Vuex or EventBus. These alternatives are provided to meet component communication needs in different scenarios.

Summary

Through provide and inject, we can easily achieve cross-level component communication. Provide and inject provide a flexible way to share data and methods, especially suitable for communication scenarios between some multi-level components. I hope this article can help readers better understand and apply Vue's component communication mechanism.

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