vue使用Element组件时v-for循环里的表单项验证方法

<template>
 <div class="content-body">
  <el-form ref="form" :model="form" :rules="rules" label-width="120px">
   <el-row :gutter="10">
    <el-col :span="12" :offset="0">
     <el-form-item label="套餐名称：" prop="activityName" id="activityName">
      <el-input v-model="form.activityName"></el-input>
     </el-form-item>
    </el-col>
   </el-row>
   <el-row :gutter="10">
    <el-col :span="12">
     <el-form-item label="状态：">
      <el-radio v-model="form.status" label="1">上线</el-radio>
      <el-radio v-model="form.status" label="0">下线</el-radio>
     </el-form-item>
    </el-col>
   </el-row>
   <el-row :gutter="10">
    <el-col :span="2" style="width:120px;">
     <div class="sub-title">梯度设置：</div>
    </el-col>
    <el-col :span="20">
      <el-row :gutter="10" v-for="(item,index) in form.productGroup" :key="index">
       <el-col :span="6">
        <el-form-item label="商品数量:">
         <el-input v-model="item.num" type="number" size="small" style="width:80px;"></el-input>
        </el-form-item>
       </el-col>
       <el-col :span="6">
        <el-form-item label="优惠价格:">
          <el-input v-model="item.price" type="number" size="small" style="width:80px;"></el-input>
        </el-form-item>
       </el-col>
       <el-col :span="4">
        <i class="el-icon-remove-outline" @click="deleteLadder(index)"></i>&nbsp;&nbsp;
        <i class="el-icon-circle-plus-outline" @click="addLadder" v-if="index==0"></i>
       </el-col>
      </el-row>
    </el-col>
   </el-row>
   <el-form-item size="medium" class="div-submit">
    <el-button @click="resetForm('form')">取消</el-button>
    <el-button type="primary" @click="submitForm('form')">提交</el-button>
   </el-form-item>
  </el-form>
 </div>
</template>
<script>
/* eslint-disable */
export default {
 data() {
  return {
   form: {
    activityName: '',
    status: '1',
    productGroup: [{num:"",price:""}]
   },
   rules: {
    activityName: [
     { required: true, message: '请输入套餐名称', trigger: 'blur' }
    ]
   }
  }
 },
 methods: {
  deleteLadder(index)
  {
   if(this.form.productGroup.length>1){
    this.form.productGroup.splice(index,1);
   }
  },
  addLadder()
  {
   this.form.productGroup.push({num:"",price:""});
  },
  submitForm(formName)
  {
   console.log("activityName...",this.form.activityName);
   this.$refs[formName].validate((valid,obj) => {
    if (valid) {
     this.submitFormAction();
    } else {
     this.$message.error("验证不通过");
    }
   });
  },
  submitFormAction()
  {
   this.$message.success("提交成功");
  },
  resetForm(formName)
  {
   this.$refs[formName].resetFields();
   this.form.productGroup = [{num:"",price:""}];
  }
 }
}

</script>
<style>
.el-form-item {
 margin-bottom: 20px;
}
</style>

productGroupRules: {
 productGroupNum: [{required: true, message: '请填写商品数量', trigger: 'blur'}],
 productGroupPrice: [{required: true, message: '请填写优惠价格', trigger: 'blur'}]
}

<el-form-item label="商品数量:" :prop="'productGroup.'+index+'.num'" :rules="productGroupRules.productGroupNum">
 <el-input v-model="item.num" type="number" size="small" style="width:80px;"></el-input>
</el-form-item>

form: {
 activityName: '',
 status: '1',
 productGroup: [{num:"",price:""}]
}
如果是：

form: {
 activityName: '',
 status: '1'
},
productGroup: [{num:"",price:""}]