最近在写后台管理系统，遇到一个问题是关于菜单/按钮权限的处理：

效果图如下：

1.需求说明

点击编辑API权限，弹窗如上图所示：
弹窗内容分左右两部分，左侧是大类，右侧是子类及孙子类，其中所有的项目都要展开显示。

2.如何展开所有子项及孙子项目——在弹窗之前就获取树形结构，然后直接将数据传到弹窗中

在弹窗之前就要调用接口获取数据：

1：`addPermission`就是弹窗的组件
2：getCrmPermissionTree 获取权限tree的接口

handleAPI(row){
	let permissionList = [];
	this.loading = true;
	getCrmPermissionTree()
	  .then((res) => {
	    permissionList = res || [];
	    this.$refs.addPermission.handleShow(row, permissionList);
	  })
	  .finally(() => {
	    this.loading = false;
	  });
}

3.template部分代码

<a-modal
    title="编辑API权限"
    :visible.sync="visible"
    width="500px"
    :maskClosable="true"
    @cancel="handleClose"
    @ok="handleSubmit"
  >
    <div id="topId"></div>
    <a-tabs tab-position="left">
      <a-tab-pane
        forceRender
        v-for="(group, index) in permissionList"
        :key="index + 1"
        :tab="group.displayName"
      >
        <a-tree
          ref="permissionTree"
          v-model="group.value"
          checkable
          checkStrictly
          :defaultExpandAll="true"
          :treeData="group.permissions"
          :replaceFields="replaceFields"
          @check="onCheck($event, group)"
        />
      </a-tab-pane>
    </a-tabs>
  </a-modal>

4.script的data部分

data(){
	return{
	  visible: false,
      loadLoading: false,
      permissionList: [],
      checkedKeys: [],
      id: undefined,
      replaceFields: {
        value: 'permissionName',
        title: 'displayName',
        children: 'children',
        key: 'permissionName',
      },
      menuRoteIds: [],
	}
},
methods:{
	onCheck(obj, item) {
      item.value = obj.checked || [];
      this.$forceUpdate();
    },
}

5.权限tree数据处理——将row中的权限分配到具体的value参数中

handleShow(row, permissionList) {
  this.visible = true;
  this.id = row.id;
  this.permissionList = [...permissionList];
  this.menuRoteIds = [...row.permissionNames];
  this.permissionList.forEach((item) => {
    item.value = [];
    if (this.menuRoteIds.includes(item.id)) {
      item.value.push(item.id);
    }
    if (item.children && item.children.length > 0) {
      item = this.filterMenuList(item.children, item);
    }
  });
  this.$nextTick(() => {
  	//这一步是为了弹窗打开的时候滚动到页面顶部，在页面顶部有个`topId`的dom元素
    document.getElementById('topId').scrollIntoView(true);
  });
},
filterMenuList(arr, item) {
  arr.forEach((child) => {
    this.expandedKeys.push(child.id);
    if (this.menuRoteIds.includes(child.id)) {
      item.value.push(child.id);
    }
    if (child.children && child.children.length > 0) {
      child = this.filterMenuList(child.children, item);
    }
  });
  return item;
},

6.权限的保存——handleSubmit

handleClose() {
  this.visible = false;
},
handleSubmit() {
  let arr = [];
  this.permissionList &&
    this.permissionList.forEach((item) => {
      arr = arr.concat(item.value);
    });
  let params = {
    permissionNames: arr || [],
  };
  this.loadLoading = true;
  putApiPermission(this.id, params)
    .then(() => {
      this.$message.success('保存成功');
      this.$emit('ok');
      this.handleClose();
    })
    .finally(() => {
      this.loadLoading = false;
    });
},