element 中 Table分页回显勾选数据

配合row-key -->行数据的 Key，用来优化 Table 的渲染；在使用 reserve-selection 功能的情况下来进行回显
一 html

 <el-table :data="dataList" :row-key="getRowKeys" stripe border ref="multipleTable" tooltip-effect="dark" @selection-change="changeFun_good">
      <el-table-column type="selection" :reserve-selection="true" width="55" align="center"></el-table-column>
      <el-table-column type="index" label="序号" width="50" align="center"></el-table-column> 
      <el-table-column prop="name" label="商品名称" align="center"></el-table-column>
      <el-table-column prop="goodsUnit" label="单位" align="center"></el-table-column>
      <el-table-column prop="purchasePrice" label="单价" align="center"></el-table-column> 
      <el-table-column prop="goodsQuantity" label="库存数量" align="center"></el-table-column>
    </el-table>

二 return

 return {
      getRowKeys (row) {
        return row.id;
      },
      dataList: []
    };

三，methods

    changeFun_good (val) {
      this.chooseData = val;
    },