项目要求：类型为“业务备货”的时候，“客户”为必填项

效果如下：

代码如下：

<!--      :validate-on-rule-change="false" 是为了阻止更改rules时立即触发校验-->
<el-form :model="form" ref="orderForm" :rules="formRules" :validate-on-rule-change="false">
        <el-form-item label="类型" prop="type">
          <el-radio-group v-model="form.type" @change="needCustNm">
            <el-radio-button value="1" label="采购备货"></el-radio-button>
            <el-radio-button value="2" label="业务备货"></el-radio-button>
          </el-radio-group>
        </el-form-item>
        <el-form-item label="客户" prop="custNm">
          <el-input v-model="form.custNm" placeholder="请输入客户"></el-input>
        </el-form-item>
</el-form>


......
// 初始化设置
const formRules = ref({
  type: [
    {
      required: true,
      message: '请选择类型',
      trigger: 'change',
    },
  ]
});

// 切换类型时
function needCustNm(){
  if(form.value.type == '2'){
    formRules.value = {
      type: [
        {
          required: true,
          message: '请选择类型',
          trigger: 'change',
        },
      ],
      custNm:[
        {
          required: true,
          message: '请输入客户',
          trigger: 'change',
        },
      ]
    }
  }else{
    formRules.value = {
      type: [
        {
          required: true,
          message: '请选择类型',
          trigger: 'change',
        },
      ]
    }
  //  需要加nextTick,不然获取不到
    nextTick(()=>{
      // 清除校验效果
      proxy.$refs["orderForm"] && proxy.$refs["orderForm"].clearValidate()
    })
  }
}

重点：

 :validate-on-rule-change="false" 是为了阻止更改rules时立即触发校验

nextTick(()=>{
      // 清除校验效果
      proxy.$refs["orderForm"] && proxy.$refs["orderForm"].clearValidate()
})