Select form Verification under element table

each row under el-table has an el-select selected value that is bound to the selectedPosition array under the ruleForm object. In this case, how can I validate each row of select? for example, if the select in the first row is not selected, verify whether the select has a selected value in blur
< el-form: model= "ruleForm": rules="rules" >

.
    <el-table 
      :data="detailList" 
      style="width: 100%" 
      header-row-class-name="blackTableHeader">
      <el-table-column prop="index" label=""  align="center">
          <template slot-scope="scope">
              {{scope.$index+1}} 
        </template>
      </el-table-column>
      <el-table-column prop="name" label=""  align="center"></el-table-column>
      <el-table-column prop="position" label="" align="center">
          <template slot-scope="scope">
          <el-form-item prop="selectedPosition" :rules="[{ required: true, message: "", trigger: "blur"}]">
              <el-select 
                  v-model="ruleForm.selectedPosition[scope.$index]" 
                  @change="handleChange(scope.row,$event)" 
                  placeholder="">
                <el-option
                  v-for="(item,idx) in positionList"
                  :key="idx"
                  :label="item.name"
                  :value="item.dataKey">
                </el-option>
             </el-select>
          </el-form-item>
        </template>
      </el-table-column>
      <el-table-column prop="operation" label="" align="center">
          <template slot-scope="scope">
          <span class="delete" @click="deleteRow(scope,detailList)"></span>
        </template>
      </el-table-column>
    </el-table>
</el-form>
      
      ruleForm: {
                selectedPosition: []
            }
May.15,2022
MySQL Query : SELECT * FROM `codeshelper`.`v9_news` WHERE status=99 AND catid='6' ORDER BY rand() LIMIT 5
MySQL Error : Disk full (/tmp/#sql-temptable-64f5-1b2b0b2-2ba60.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
MySQL Errno : 1021
Message : Disk full (/tmp/#sql-temptable-64f5-1b2b0b2-2ba60.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
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