前言

在前端开发中，平时在填写表单中，可能会遇到需要展示选择树状数据的表单组件。但是在element中，并未提供能够处理树状数据选择的 select 选择框组件。所以就此，小温在开发中遇到类似的问题，封装了elementUi 的 select选择框组件。接下来给大家讲述一下！ 希望能给大家一些帮助！

提示：以下是本篇文章正文内容，下面案例仅供参考

一、树状部门数据 下拉框单选

效果图如下：

实现代码：

> 组件代码 （ 父 ）

<el-form-item label="单位名称: ">
  <SelectTree
    style="width: 100%"
    ref="selectTreeRef"
    :props="defaultProps"
    :options="treeData"
    :value="valueId"
    :clearable="true"
    :accordion="true"
    @getValue="getValue($event)"
  />
</el-form-item>

// 树状数据中，选定子元素名，展示名，选中值变量名
defaultProps: {
  children: "list",
  label: "orgName",
  value: "orgId",
},
// 树状数据
treeData: [],
// 初始展开
valueId: '',

> 组件代码 （ 子 ）

此为 vue文件
<template>
  <el-select v-model="valueTitle" placeholder="请选择" :clearable="clearable" @clear="clearHandle">
    <el-option :value="valueTitle" :label="valueTitle" class="options">
      <el-tree  
        id="tree-option"
        ref="selectTree"
        :accordion="accordion"
        :data="options"
        :props="props"
        :node-key="props.value"    
        :default-expanded-keys="defaultExpandedKey"
        @node-click="handleNodeClick">
      </el-tree>
    </el-option>
  </el-select>
</template>

<script>
export default {
  name: "el-tree-select",
  props:{
    // 配置项
    props:{
      type: Object,
      default: () => {
        return {
          value:'id',             // ID字段名
          label: 'title',         // 显示名称
          children: 'children'    // 子级字段名
        };
      }
    },
    
    // 选项列表数据(树形结构的对象数组)
    options:{ type: Array, default: () => { return [] } },
    
    // 初始值
    value:{ type: String, default: () => { return null } },
    
    // 可清空选项
    clearable:{ type:Boolean, default: () => { return true } },
    
    // 自动收起
    accordion:{ type:Boolean, default: () => { return false } }
  },

  data() {
    return {
      valueId: null,
      valueTitle:'',
      defaultExpandedKey:[]    
    }
  },
  mounted(){
    this.valueId = this.value,    // 初始值
    this.initHandle()
  },
  methods: {
    // 初始化值
    initHandle(){
      if(this.valueId){
        setTimeout(() => {
          window.console.log(this.options)
          this.valueTitle = this.$refs.selectTree.getNode(Number(this.valueId)).data[this.props.label]     // 初始化显示
          this.$refs.selectTree.setCurrentKey(Number(this.valueId))       // 设置默认选中
          this.defaultExpandedKey = [this.valueId]      // 设置默认展开
        }, 500);
      } else {
        this.valueTitle = ""
      }
      this.initScroll()
    },

    // 初始化滚动条
    initScroll(){
      this.$nextTick(()=>{
        let scrollWrap = document.querySelectorAll('.el-scrollbar .el-select-dropdown__wrap')[0]
        let scrollBar = document.querySelectorAll('.el-scrollbar .el-scrollbar__bar')
        scrollWrap.style.cssText = 'margin: 0px; max-height: none; overflow: hidden;'
        scrollBar.forEach(ele => ele.style.width = 0)
      })
    },

    // 切换选项
    handleNodeClick(node, obj){
      window.console.log(obj);
      // if(obj.level <= 1 ) return false
      this.valueTitle = node[this.props.label]
      this.valueId = node[this.props.value]
      this.$emit('getValue', [this.valueId,this.valueTitle])
      this.defaultExpandedKey = []
    },

    // 清除选中
    clearHandle(){
      this.valueTitle = ''
      this.valueId = null
      this.defaultExpandedKey = []
      this.clearSelected()
      this.$emit('getValue', [this.valueId,this.valueTitle])
    },

    // 清空选中样式
    clearSelected(){
      let allNode = document.querySelectorAll('#tree-option .el-tree-node')
      allNode.forEach((element)=>element.classList.remove('is-current'))
    }

  },

  watch: {
    value(){
      this.valueId = this.value
      this.initHandle()
    }
  },
}
</script>

<style scoped>
  .el-scrollbar .el-scrollbar__view .el-select-dropdown__item{
    height: auto;
    max-height: 274px;
    padding: 0;
    overflow: hidden;
    overflow-y: auto;
  }
  .el-select-dropdown__item.selected{
    font-weight: normal;
  }
  ul li >>>.el-tree .el-tree-node__content{
    height:auto;
    padding: 0 20px;
  }
  .el-tree-node__label{
    font-weight: normal;
  }
  .el-tree >>>.is-current .el-tree-node__label{
    color: #409EFF;
    font-weight: 700;
  }
  .el-tree >>>.is-current .el-tree-node__children .el-tree-node__label{
    color:#606266;
    font-weight: normal;
  }
</style>

二、树状部门数据 下拉框单选

效果图如下：

解释：多选和单选的代码差不多，就不做庸余的复制粘贴了。

• 需要注意的就是，在父组件中，初始值 valueId 为一个数组，因为可多选的原因，返回方法接受的值也为一个数组。
• 在赋值给 elementUi 的 select组件时，也需要将 所选内容进行处理。具体不同的，下面贴一下代码！

<template>
  <el-select :value="valueTitle" :clearable="clearable" @clear="clearHandle">
    <el-option :value="valueTitle" :label="valueTitle" class="options">
      <el-tree
        id="tree-option"
        ref="selectTree"
        :accordion="accordion"
        :data="options"
        :props="props"
        :node-key="props.value"
        :default-expanded-keys="defaultExpandedKey"
        :filter-node-method="filterNode"
        @node-click="handleNodeClick"
      >
      </el-tree>
    </el-option>
  </el-select>
</template>
 
<script>
export default {
  name: "el-tree-select",
  props: {
    /* 配置项 */
    props: {
      type: Object,
      default: () => {
        return {
          value: "id", // ID字段名
          label: "title", // 显示名称
          children: "children", // 子级字段名
        };
      },
    },
    /* 选项列表数据(树形结构的对象数组) */
    options: {
      type: Array,
      default: () => {
        return [];
      },
    },
    /* 初始值 */
    value: {
      type: Array,
      default: () => {
        return [];
      },
    },
    /* 可清空选项 */
    clearable: {
      type: Boolean,
      default: () => {
        return true;
      },
    },
    /* 自动收起 */
    accordion: {
      type: Boolean,
      default: () => {
        return false;
      },
    },
  },
  data() {
    return {
      filterText: "",
      valueId: '', // 初始值
      valueTitle: "",
      defaultExpandedKey: [],
      selectData:[]
    };
  },
  mounted() {
    this.initHandle();
  },
  methods: {
    // 初始化值
    initHandle() {
      // window.console.log(this.$refs.selectTree)
      if (Array.isArray(this.value) && this.value.length !== 0) {
        // window.console.log(this.$refs.selectTree.getNode(10036), '***')
        this.value.forEach(item => {
          this.valueTitle += `${item[this.props.label]}，`
        });
        this.selectData = JSON.parse(JSON.stringify(this.value));
        // this.$refs.selectTree.setCurrentKey(this.valueId); // 设置默认选中
        this.defaultExpandedKey = [...(this.value.map(item => item[this.props.value]))]; // 设置默认展开
      }
      this.initScroll();
    },
    // 初始化滚动条
    initScroll() {
      this.$nextTick(() => {
        let scrollWrap = document.querySelectorAll(
          ".el-scrollbar .el-select-dropdown__wrap"
        )[0];
        let scrollBar = document.querySelectorAll(
          ".el-scrollbar .el-scrollbar__bar"
        );
        scrollWrap.style.cssText =
          "margin: 0px; max-height: none; overflow: hidden;";
        scrollBar.forEach((ele) => (ele.style.width = 0));
      });
    },
    // 切换选项
    handleNodeClick(node) {
      // window.console.log(node)
      if (Array.isArray(node[this.props.children]) && node[this.props.children].length !== 0) {
        return;
      } else {
        let val ='';
        // window.console.log(node)
        if (!this.selectData.some( item => {
          return item[this.props.value] == node[this.props.value]
        })) {
          this.selectData.push(node)
          this.selectData.forEach(el=> val += `${el[this.props.label]}，`);
          this.valueTitle = val;
          this.valueId = node[this.props.value];
          this.$emit("getValue", this.selectData);
          this.defaultExpandedKey = [];
        }
      }
    },
    // 清除选中
    clearHandle() {
      this.valueTitle = "";
      this.valueId = "";
      this.defaultExpandedKey = [];
      this.selectData = []
      this.clearSelected();
      this.$emit("getValue", null);
    },
    /* 清空选中样式 */
    clearSelected() {
      let allNode = document.querySelectorAll("#tree-option .el-tree-node");
      allNode.forEach((element) => element.classList.remove("is-current"));
    },
    filterNode(value, data) {
      if (!value) return true;
      return data.name.indexOf(value) !== -1;
    },
  },
  watch: {
    value() {
      // this.valueId = this.value;
      this.initHandle();
    },
    filterText(val) {
      this.$refs.selectTree.filter(val);
    },
    // options(val) {
    //   window.console.log(val)
    // }
  },
};
</script>
 
<!-- Add "scoped" attribute to limit CSS to this component only -->
<style scoped>
.el-scrollbar .el-scrollbar__view .el-select-dropdown__item {
  height: auto;
  max-height: 274px;
  padding: 0;
  overflow: hidden;
  overflow-y: auto;
}
.el-select-dropdown__item.selected {
  font-weight: normal;
}
ul li >>> .el-tree .el-tree-node__content {
  height: auto;
  padding: 0 20px;
}
.el-tree-node__label {
  font-weight: normal;
}
.el-tree >>> .is-current .el-tree-node__label {
  color: #409eff;
  font-weight: 700;
}
.el-tree >>> .is-current .el-tree-node__children .el-tree-node__label {
  color: #606266;
  font-weight: normal;
}
.selectInput {
  padding: 0 5px;
  box-sizing: border-box;
}
/* 开发禁用 */
/* .el-tree-node:focus>.el-tree-node__content{
    background-color:transparent;
    background-color: #f5f7fa;
    color: #c0c4cc;
    cursor: not-allowed;
  }
  .el-tree-node__content:hover{
    background-color: #f5f7fa;
  } */
</style>

总结

大致内容就到这里结束啦，如果觉得有帮助的话！ 希望不要吝啬手中的赞！ 给小温点点赞！点个关注吧！