用表单时经常需要校验表单项

正常用法如下：

<el-form-item label="分辨率" prop="resolvingPower">
  <el-select v-model="form.resolvingPower" style="float: left; width: 100%">
    <el-option
      v-for="item in resolvingOption"
      :key="item.value"
      :label="item.name"
      :value="item.value"
    >
    </el-option>
  </el-select>
</el-form-item>

但有时候校验需要另外处理，表单上需要弄个类似的小红星

<el-form-item prop="applicationAlgorithm1">
              <span slot="label">
                <span style="color: #F56C6C">* </span>
                <span>分辨率</span>
              </span>
              <el-checkbox-group v-model="form.applicationAlgorithm" :max="4" @change="handleCheckedChange">
                <el-checkbox v-for="(item,index) in algorithmArray"
                             :key="index"
                             :label="item.id"
                >
                  {{ item.name }}
                </el-checkbox>
              </el-checkbox-group>
            </el-form-item>