el-tree懒加载时的箭头隐藏

                    <el-tree
                    class='tree-padding'
                    :data="api_management_case_tree"
                    ref="tree"
                    show-checkbox
                    :highlight-current="true"
                    node-key="id"
                    :default-expand-all="false"
                    :load="loadNode"
                    :expand-on-click-node="false"
                    lazy
                    :default-expanded-keys="[]"
                    :default-checked-keys="[defaultCase]"
                    :props="defaultProps"
                    >
                　　</el-tree>

　　

解决方式：

 loadNode(node, resolve) {
      if (node.level == 0) {
        console.log(node.level)
      }
      if (node.level > 4) {
        return resolve([]);
      }
      if (node.level >= 1 && node.level <=3) {
        let req = {
          "parent":node.data.id,
          "isLeaf": 'false'
        }
        postApiManagementTreeRequest(req).then(data => {
          if (true === data.data.success){
            this.resolve = data.data.data
            return resolve(data.data.data);
          }else {
            this.$message.error(data.data.message)
          }
        })
      }
      if (node.level == 4) {
        let req = {
          "parent":node.data.id
        }
        postApiScenariosCaseRequest(req).then(data => {
          if (true === data.data.success){

            data.data.data.forEach(item=>{
              if(true === item.isParent){
                item.isLeaf = true
              }
            })
            return resolve(data.data.data)
          }else {
            this.$message.error(data.data.message)
          }
        })
      }
    },