本節講述了elementui tree 可拖拽節點的使用

通過 draggable 屬性可讓節點變為可拖拽。

allow-drop判定目標節點能否被放置。allow-drop是個函式型別的屬性

Function(draggingNode, dropNode, type)

draggingNode當前拖動的節點

dropNode要拖動到哪個節點

type引數有三種情況：'prev'、'inner' 和 'next'，分別表示放置在目標節點前、插入至目標節點和放置在目標節點後

本節原始碼：測試拖動發現有點小bug，估計原視訊也有，不是大問題，學習為主就不糾結了

<template>
 

  <div>
    <el-tree
      :data="menus"
      :props="defaultProps"
      show-checkbox=""
      node-key="catId"
      :expand-on-click-node="false"
      :default-expanded-keys="expandedkey"
      draggable
      :allow-drop="allowDrop"
    >
      <span class="custom-tree-node" slot-scope
 
="{ node, data }">
        <span>{{ node.label }}</span>
        <span>
          <el-button
            v-if="node.level <= 2"
            type="text"
            size="mini"
            @click="() => append(data)"
          >
            Append
          </el-button
 
>
          <el-button
            v-if="node.level <= 2"
            type="text"
            size="mini"
            @click="() => edit(data)"
          >
            edit
          </el-button>
          <el-button
            v-if="node.childNodes.length == 0"
            type="text"
            size="mini"
            @click="() => remove(node, data)"
          >
            Delete
          </el-button>
        </span>
      </span>
    </el-tree>
    <el-dialog
      :title="title"
      :visible.sync="dialogVisible"
      width="30%"
      :close-on-click-modal="false"
    >
      <el-form :model="category">
        <el-form-item label="分類名稱">
          <el-input v-model="category.name" autocomplete="off"></el-input>
        </el-form-item>
      </el-form>
      <el-form :model="category">
        <el-form-item label="圖示">
          <el-input v-model="category.icon" autocomplete="off"></el-input>
        </el-form-item>
      </el-form>
      <el-form :model="category">
        <el-form-item label="計量單位">
          <el-input
            v-model="category.productUnit"
            autocomplete="off"
          ></el-input>
        </el-form-item>
      </el-form>
      <span slot="footer" class="dialog-footer">
        <el-button @click="dialogVisible = false">取 消</el-button>
        <el-button type="primary" @click="submitData">確 定</el-button>
      </span>
    </el-dialog>
  </div>
</template>

<script>
//這裡可以匯入其他檔案（比如：元件，工具js，第三方外掛js，json檔案，圖片檔案等等）
//例如：import《元件名稱》from'《元件路徑》';

export default {
  data() {
    return {
      maxLevel: 0,
      title: "",
      dialogType: "",
      category: {
        name: "",
        parentCid: 0,
        catLevel: 0,
        showStatus: 1,
        sort: 0,
        catId: null,
        icon: "",
        productUnit: "",
      },
      dialogVisible: false,
      expandedkey: [],
      menus: [],
      defaultProps: {
        children: "children",
        label: "name",
      },
    };
  },
  created() {
    console.log(this.expandedkey);
    this.getMenus();
  },
  methods: {
    allowDrop(draggingNode, dropNode, type) {
      //1、被拖動的當前節點以及所在的父節點總層數不能大於3
      console.log("allowDrop:", draggingNode, dropNode, type);
      this.countNodeLevel(draggingNode);
      //當前正在拖動的節點+父節點所在的深度不大於3即可
      let deep = Math.abs(this.maxLevel - draggingNode.level) + 1;
      console.log("深度：", deep);
      if (type == "inner") {
        return deep + dropNode.level <= 3;
      } else {
        return deep + dropNode.parent.level <= 3;
      }
    },
    countNodeLevel(node) {
      //找到所有子節點，求出最大深度
      if (node.childNodes != null && node.childNodes.length > 0) {
        for (let i = 0; i < node.childNodes.length; i++) {
          if (node.childNodes[i].level > this.maxLevel) {
            this.maxLevel = node.childNodes[i].level;
          }
          this.countNodeLevel(node.childNodes[i]);
        }
      }
    },
    submitData() {
      if (this.dialogType == "add") {
        this.addCategory();
      } else if (this.dialogType == "edit") {
        this.editCategory();
      }
    },
    editCategory() {
      alert(this.dialogType);
      var { catId, name, icon, productUnit } = this.category;
      this.$http({
        url: this.$http.adornUrl("/product/category/update"),
        method: "post",
        data: this.$http.adornData({ catId, name, icon, productUnit }, false),
      }).then(({ data }) => {
        this.$message({
          message: "選單修改成功",
          type: "success",
        });
        //關閉對話方塊
        this.dialogVisible = false;
        //刷新出新的選單
        this.getMenus();
        //設定需要預設展開的選單
        this.expandedkey = [this.category.parentCid];
      });
    },
    edit(data) {
      console.log(data);
      this.title = "修改分類";
      this.dialogType = "edit";
      this.dialogVisible = true;

      //傳送請求獲取當前節點最新的資料
      this.$http({
        url: this.$http.adornUrl(`/product/category/info/${data.catId}`),
        method: "get",
      }).then(({ data }) => {
        //請求成功
        console.log("要回顯的資料", data);
        this.category.name = data.data.name;
        this.category.catId = data.data.catId;
        this.category.icon = data.data.icon;
        this.category.productUnit = data.data.productUnit;
        this.category.parentCid = data.data.parentCid;
        this.category.catLevel = data.data.catLevel;
        this.category.sort = data.data.sort;
        this.category.showStatus = data.data.showStatus;
      });
    },
    addCategory() {
      this.$http({
        url: this.$http.adornUrl("/product/category/save"),
        method: "post",
        data: this.$http.adornData(this.category, false),
      }).then(({ data }) => {
        this.$message({
          message: "選單儲存成功",
          type: "success",
        });
        //關閉對話方塊
        this.dialogVisible = false;
        //刷新出新的選單
        this.getMenus();
        //設定需要預設展開的選單
        this.expandedkey = [this.category.parentCid];
      });
    },
    remove(node, data) {
      let ids = [data.catId];
      console.log(ids);
      console.log(node);
      this.$confirm(`是否刪除${data.name}選單？`, "提示", {
        confirmButtonText: "確定",
        cancelButtonText: "取消",
        type: "warning",
      })
        .then(() => {
          this.$http({
            url: this.$http.adornUrl("/product/category/delete"),
            method: "post",
            data: this.$http.adornData(ids, false),
          }).then(({ data }) => {
            this.$message({
              message: "選單刪除成功",
              type: "success",
            });
            this.getMenus();
            console.log(node.parent.data.catId);
            this.expandedkey = [node.parent.data.catId];
          });
        })
        .catch(() => {});
    },
    append(data) {
      this.dialogType = "add";
      this.title = "新增分類";
      this.dialogVisible = true;
      this.category.parentCid = data.catId;
      this.category.catLevel = data.catLevel * 1 + 1;

      this.category.catId = null;
      this.category.name = "";
      this.category.icon = "";
      this.category.productUnit = "";
      this.category.sort = 0;
      this.category.showStatus = 1;
    },

    getMenus() {
      this.$http({
        url: this.$http.adornUrl("/product/category/list/tree"),
        method: "get",
      }).then(({ data }) => {
        console.log("成功獲取選單", data.data);
        this.menus = data.data;
        console.log("thismenus", this.menus);
      });
    },
  },
};
</script>
<stylescoped>
</style>