The relationship between components

Define and use relationships between components

Sometimes it is necessary to implement components such as:

<custom-ul>
  <custom-li> item 1 </custom-li>
  <custom-li> item 2 </custom-li>
</custom-ul>

In this example, custom-ul and custom-li are custom components that have relationships with each other and often communicate more complexly with each other. Y ou can solve this problem by adding a relations definition segment to the component definition. Example:

// path/to/custom-ul.js
Component({
  relations: {
    './custom-li': {
      type: 'child', // 关联的目标节点应为子节点
      linked: function(target) {
        // 每次有custom-li被插入时执行，target是该节点实例对象，触发在该节点attached生命周期之后
      },
      linkChanged: function(target) {
        // 每次有custom-li被移动后执行，target是该节点实例对象，触发在该节点moved生命周期之后
      },
      unlinked: function(target) {
        // 每次有custom-li被移除时执行，target是该节点实例对象，触发在该节点detached生命周期之后
      }
    }
  },
  methods: {
    _getAllLi: function(){
      // 使用getRelationNodes可以获得nodes数组，包含所有已关联的custom-li，且是有序的
      var nodes = this.getRelationNodes('path/to/custom-li')
    }
  },
  ready: function(){
    this._getAllLi()
  }
})

// path/to/custom-li.js
Component({
  relations: {
    './custom-ul': {
      type: 'parent', // 关联的目标节点应为父节点
      linked: function(target) {
        // 每次被插入到custom-ul时执行，target是custom-ul节点实例对象，触发在attached生命周期之后
      },
      linkChanged: function(target) {
        // 每次被移动后执行，target是custom-ul节点实例对象，触发在moved生命周期之后
      },
      unlinked: function(target) {
        // 每次被移除时执行，target是custom-ul节点实例对象，触发在detached生命周期之后
      }
    }
  }
})

Note: The system definition must be included in both component definitions, otherwise it will not take effect.

Associate a class of components

Sometimes, a class of components needs to be associated, such as:

<custom-form>
  <view>
    input
    <custom-input></custom-input>
  </view>
  <custom-submit> submit </custom-submit>
</custom-form>

The custom-form component wants to associate the custom-input and custom-submit components. At this point, if both components have the same behavior:

// path/to/custom-form-controls.js
module.exports = Behavior({
  // ...
})

// path/to/custom-input.js
var customFormControls = require('./custom-form-controls')
Component({
  behaviors: [customFormControls],
  relations: {
    './custom-form': {
      type: 'ancestor', // 关联的目标节点应为祖先节点
    }
  }
})

// path/to/custom-submit.js
var customFormControls = require('./custom-form-controls')
Component({
  behaviors: [customFormControls],
  relations: {
    './custom-form': {
      type: 'ancestor', // 关联的目标节点应为祖先节点
    }
  }
})

In the relations relationship definition, you can use this behavior instead of the component path as the associated target node:

// path/to/custom-form.js
var customFormControls = require('./custom-form-controls')
Component({
  relations: {
    'customFormControls': {
      type: 'descendant', // 关联的目标节点应为子孙节点
      target: customFormControls
    }
  }
})

Relations defines the segment

The relations definition segment contains the target component path and its corresponding options, which can be included in the table below.