Tips for using provide and inject in Vue to transfer data from ancestor components to descendant components

Vue is a very flexible and powerful front-end framework that provides many convenient functions, including provide and inject. These two functions can help us transfer data from ancestor components to descendant components, which is very practical. However, using these features is not very easy, especially for beginners. In this article, I will explain how to use these features to implement techniques for passing data from ancestor components to descendant components.

What are provide and inject?

In Vue, provide and inject are a pair of component options that are used to pass data from ancestor components to descendant components. The provide option allows an ancestor component to provide data to all its descendant components, while the inject option allows a descendant component to inject data into its ancestor components.

How to use provide and inject

The basic method of using provide and inject is as follows:

1. To provide data for ancestor components, please use the provide option

Use the provide option in ancestor components to provide data. The value of provide must be an object. The property name of the object can be arbitrary, but the property value must be a data object or a calculated property function. For example:

Vue.component('ancestor-component', {
  provide: {
    name: 'Alice',
    age: 20,
    address: {
      city: 'Beijing',
      district: 'Haidian'
    },
    calcSalary: function () {
      return 10000
    }
  },
  // ...
})

In this example, we use provide to provide several data items: name, age, address and calcSalary. Among them, calcSalary is a calculated attribute function that returns the calculation result of salary. These values ​​are available in descendant components.

2. To receive data in descendant components, use the inject option

Use the inject option in descendant components to receive data. The value of this option is an array or object containing the data from the ancestor component's provide option. For example:

Vue.component('descendant-component', {
  inject: {
    name: 'name',
    age: 'age',
    address: 'address',
    calcSalary: 'calcSalary'
  },
  mounted: function () {
    console.log(this.name) // Alice
    console.log(this.age) // 20
    console.log(this.address.city) // Beijing
    console.log(this.address.district) // Haidian
    console.log(this.calcSalary()) // 10000
  }
})

In this example, we use the inject option to receive the data in the provide option of the ancestor component. Note that the value of inject is an object, the key of the object is the attribute name of the descendant component, and the value is the corresponding attribute name of the ancestor component provide. For example, in the above code, name corresponds to 'name', age corresponds to 'age', address corresponds to 'address', and calcSalary corresponds to 'calcSalary'.

Note

1. provide and inject can only pass data between parent and child components. If you want to pass data between sibling components, you can consider using Vuex or event bus (EventBus).
2. When using provide and inject, pay attention to the naming of attribute names. If the property names are the same, the property value received by the descendant component will be the property value provided by the ancestor component. If the property names are different, the property value received by the descendant component will be undefined.
3. When using provide and inject, pay attention to data type issues. The data provided should use reference types such as objects or functions, rather than simple types. This is because simple types create new memory spaces when assigning values, so modifications to the child component will not affect the value of the parent component.

Conclusion

Using provide and inject in Vue makes it easy for ancestor components to pass data to descendant components. If you are developing a large Vue project and need to let the source component pass data to the descendant component, then the provide and inject functions will be used frequently during the project development process. What needs to be noted is the precautions mentioned earlier. Flexible use of provide and inject can make your project higher quality and more efficient.

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