[Vue.js — iView — Tree] 点击树组件父节点名称时展开、收缩后代节点

版权声明：本文为博主原创文章，转载请注明出处，谢谢。 https://blog.csdn.net/qq846294282/article/details/81910653

适用于iview tree。

```
<Tree ref="tree" :data="data" :load-data="loadData" @on-select-change="selectChange" show-checkbox/>
```


```
data() {
  return {
    data: [],
    id: 0
  }
},
methods: {
  loadData (item, callback) {
    this._loadData(item.id, callback)
  },
  _loadData (code, callback) {
    this.$http.get('/service-cutover/datasets/complaints/types?pcode=' + code).then((response) => {
      const array = []
      for (let i = 0; i < response.data.length; i++) {
        let item = response.data[i]
        array.push(item = {id: item.code, title: item.name, loading: false, children: [], source: item})
        if (item.source.leaf) delete item.loading
      }
      callback(array)
    })
  }，
  selectChange (selectedList) {
    const node = selectedList[selectedList.length - 1] // 获取当前点击的节点
    if (node) {
      this._loadData(node.id, (response) => {
        if (!response) return        // 没有子节点则返回
        let array = []
        response.forEach((item) => { // 遍历子节点，然后在各子节点上递归调用请求下一层后代
          array.push(item)
          this._loadData(item.id, () => {})
        })
        node.children = array // 挂载子节点
        node.expand = true    // 展开子节点树
      })
    }
  }
},
mounted () {
  this._loadData(this.id, (array) => { // 后端逻辑是获取父节点id，返回直接后代列表
    this.data = array
  })
}
```