javascript - Vue $refs 為什麼無法取得元件對象

Question

<el-tree ref="permissions_tree" class="permissions-tree" :data="permissions" :props="basicConfig.defaultProps" show-checkbox node-key="id" :render-content="renderNode"></el-tree>

mounted () {
  console.log(this.$refs.permissions_tree);
}

在 mounted 中列印輸出的是undefined！這是為什麼？

我在表格中渲染的按鈕，第一次點選呼叫 console.log(this.$refs.permissions_tree);得到的也是 undefined，第二次就能正常取得到元件了

{
    title: '操作',
    key: 'action',
    align: 'center',
    render: (h, params) => {
      return h('p', [
        h('Button', {
          props: {
            type: 'primary',
            size: 'small'
          },
          style: {
            marginRight: '5px'
          },
          on: {
            click: () => {
              this.userForm.staffid = params.row.staffid;
              this.userForm.name = params.row.name;
              this.userForm.phoneticize = params.row.phoneticize;
              this.userForm.gender = params.row.gender;
              this.userForm.mobile = params.row.mobile;
              this.userForm.telephone = params.row.telephone;
              this.userForm.identification = params.row.identification;
              this.userForm.positions = params.row.positions;
              this.userForm.permissions = params.row.permissions;
              this.userFormShow = true;
              console.log(this.$refs.permissions_tree); //这里
            }
          }
        }, '编辑')
      ]);
    }
}

#

Answer 1

可能你用v-if來切換組件展示，所以要在下一個tick才能獲取到

this.$nextTick(() => {
    console.log(this.$refs.permissions_tree);
});

Answer 2

寫在

this.$nextTick(() => {})

裡試試看

Answer 3

外層組件是不是使用了v-if，換成v-show 試試看

Answer 4

呼叫這個方法
this.$nextTick(function () {

    // 里面打印
  })