Element-UI el-table对循环产生的空白列赋默认值方式

<el-table-column label="集镇"  :prop=city >
     <template slot-scope="{row}">
         {{ row || '0' }}
       </template>
</el-table-column>

<template v-for="col in cols">
   <el-table-column :label=col.label>
     <el-table-column label="集镇" :prop=col.city >
       <template slot-scope="{row}">
         {{ row[col.city] || '0' }}
       </template>
     </el-table-column>
     <el-table-column label="农村" :prop=col.village>
       <template slot-scope="{row}">
         {{ row[col.village] || '0' }}
       </template>
     </el-table-column>       
   </el-table-column>
</template>

/deep/.el-table {
  .cell:empty::before {
    content: "---";
    color: #ccc;
  }
  .is-leaf {
    .cell:empty::before {
      content: "---";
      color: #ccc;
    }
  }
}

<el-table-column
        prop="caseTypeNames"
        label="类型"
        :formatter="caseTypeNamesFormat"
      >
</el-table-column>

    // 类型格式化
    caseTypeNamesFormat (row) {
      let showProp = null
      row.caseTypeNames ? showProp = row.caseTypeNames : showProp = '---'
      return showProp
    },