项目中使用 ElementUI 的 el-table 生成的表格，需要使用 Sortable.js 实现拖拽排序的功能，正常的拖拽没问题，但是拖拽后的数组顺序与 el-table 渲染的数据不一致，具体错误如下图所示：

查找原因发现，应该是未指定 el-table 行数据的 Key，导致 Table 渲染错误，遂添加 row-key="index" ,然而问题还是没有解决。

因为该组件通过 value 实现双向绑定，数据是通过 v-model 传递过来的，考虑数组数据按地址传值，遂使用 slice() 拷贝了新的数据，最终解决问题。

总结：
1、配置 row-key 唯一，避免 el-table 渲染数据错误；
2、拷贝数组数据，避免引用传值及双向绑定更新数据导致的错误。

<template>
  <div class="table-setting-view-container">
    <div class="settings">
      <el-select v-model="defaultSort.key" placeholder="请选择" size="mini">
        <el-option
          v-for="item in items"
          :key="item.key"
          :label="item.label"
          :value="item.key">
        </el-option>
      </el-select>
      <el-checkbox v-model="defaultSort.desc">降序</el-checkbox>
      <el-button type="primary" size="mini" @click="submit()">提交</el-button>
    </div>
    <el-table
      ref="settingTable"
      :data="items"
      row-key="index"
      border
      max-height="520"
    >
      <el-table-column label="序号" align="center" type="index" width="50" />
      <el-table-column label="显示项目" prop="label">
      </el-table-column>
      <el-table-column
        label="显示"
        width="50"
        align="center">
        <template slot-scope="scope">
          <el-checkbox v-model="scope.row.show" />
        </template>
      </el-table-column>
      <el-table-column
        prop="width"
        label="宽度"
        width="60">
        <template slot-scope="scope">
          <el-input v-model="scope.row.width" size="mini"></el-input>
        </template>
      </el-table-column>
      <el-table-column
        label="排序"
        width="50"
        align="center">
        <template slot-scope="scope">
          <el-checkbox v-model="scope.row.sort"/>
        </template>
      </el-table-column>
    </el-table>
  </div>
</template>

<script type="text/javascript">
import Sortable from 'sortablejs'

export default {
  props: {
    value: {
      type: Array,
      default: () => []
    }
  },
  data() {
    return {
      user: {},
      items: [],
      defaultSort: {key: null, desc: 0}
    };
  },
  watch: {
    value: {
      handler(newVal) {
        this.items = newVal.slice();
      },
      immediate: true,
      deep: true
    }
  },
  created() {
    this.$nextTick(() => {
      this.setSortable()
    })
  },
  methods: {
    // 拖拽排序
    setSortable() {
      const el = this.$refs.settingTable.$el.querySelectorAll('.el-table__body-wrapper > table > tbody')[0]
      this.sortable = Sortable.create(el, {
        ghostClass: 'sortable-ghost', // Class name for the drop placeholder,
        setData: function(dataTransfer) {
          dataTransfer.setData('Text', '')
        },
        onEnd: evt => {
          const targetRow = this.items.splice(evt.oldIndex, 1)[0]
          this.items.splice(evt.newIndex, 0, targetRow);
          this.items.forEach(ele => {
            console.log(ele.index, ele.label)
          });
          console.log('==================')
        }
      })
    },
    // 提交
    submit() {
      this.items =this.items.map((item, index) => {
        item.index = index + 1;
        return item;
      });
    }
  }
};
</script>
<style lang="scss" scoped>
.table-setting-view-container {
  .settings {
    margin-bottom: 10px;
    .el-checkbox {
      margin-left: 20px;
    }
    .el-button {
      float: right;
    }
  }
  ::v-deep .el-table {
    .el-table__cell {
      padding: 5px 0;
    }
    .el-input {
      .el-input__inner {
        height: 24px;
        line-height: 24px;
        padding: 0 7px;
        text-align: right;
      }
    }
    .el-select {
      width: 100%;
      .el-input__inner {
        text-align: center;
      }
    }
  }
}
</style>
<style lang="scss">
.table-view-select-popper {
  .el-select-dropdown__item {
    height: 28px;
    line-height: 28px;
    padding: 0 7px;
    text-align: center;
  }
}
</style>