这个功能为当一个下拉菜单选中某个值，确定另一个下拉框是否拥有校验规则

如图

 此时活动区域未选择值，所以测试这个下拉菜单不需要有校验

 此时活动区域选择区域一，测试拥有校验规则，非空校验

<template>
  <div id="app">
<el-form :model="ruleForm" :rules="rules" ref="ruleForm" label-width="100px" class="demo-ruleForm">
  <el-form-item label="活动名称" prop="name">
    <el-input v-model="ruleForm.name"></el-input>
  </el-form-item>
  <el-form-item label="活动区域" prop="region">
    <el-select v-model="ruleForm.region" placeholder="请选择活动区域" @change="isRules(ruleForm.region)">
      <el-option label="区域一" value="1"></el-option>
      <el-option label="区域二" value="2"></el-option>
    </el-select>
  </el-form-item>
 
<!-- 测试 -->
 <el-form-item label="测试" prop="test">
    <el-select v-model="ruleForm.test" placeholder="请选择活动区域">
      <el-option label="区域一" value="shanghai"></el-option>
      <el-option label="区域二" value="beijing"></el-option>
    </el-select>
  </el-form-item>
 
  <el-form-item label="活动时间" required>
    <el-col :span="11">
      <el-form-item prop="date1">
        <el-date-picker type="date" placeholder="选择日期" v-model="ruleForm.date1" style="width: 100%;"></el-date-picker>
      </el-form-item>
    </el-col>
    <el-col class="line" :span="2">-</el-col>
    <el-col :span="11">
      <el-form-item prop="date2">
        <el-time-picker placeholder="选择时间" v-model="ruleForm.date2" style="width: 100%;"></el-time-picker>
      </el-form-item>
    </el-col>
  </el-form-item>
  <el-form-item label="即时配送" prop="delivery">
    <el-switch v-model="ruleForm.delivery"></el-switch>
  </el-form-item>
  <el-form-item label="活动性质" prop="type">
    <el-checkbox-group v-model="ruleForm.type">
      <el-checkbox label="美食/餐厅线上活动" name="type"></el-checkbox>
      <el-checkbox label="地推活动" name="type"></el-checkbox>
      <el-checkbox label="线下主题活动" name="type"></el-checkbox>
      <el-checkbox label="单纯品牌曝光" name="type"></el-checkbox>
    </el-checkbox-group>
  </el-form-item>
  <el-form-item label="特殊资源" prop="resource">
    <el-radio-group v-model="ruleForm.resource">
      <el-radio label="线上品牌商赞助"></el-radio>
      <el-radio label="线下场地免费"></el-radio>
    </el-radio-group>
  </el-form-item>
  <el-form-item label="活动形式" prop="desc">
    <el-input type="textarea" v-model="ruleForm.desc"></el-input>
  </el-form-item>
  <el-form-item>
    <el-button type="primary" @click="submitForm('ruleForm')">立即创建</el-button>
    <el-button @click="resetForm('ruleForm')">重置</el-button>
  </el-form-item>
</el-form>
  </div>
</template>
 
<script>
  export default {
    data() {
      return {
        ruleForm: {
          name: '',
          region: '',
          date1: '',
          date2: '',
          delivery: false,
          type: [],
          resource: '',
          desc: ''
        },
        rules: {
          name: [
            { required: true, message: '请输入活动名称', trigger: 'blur' },
            { min: 3, max: 5, message: '长度在 3 到 5 个字符', trigger: 'blur' }
          ],
          region: [
            { required: true, message: '请选择活动区域', trigger: 'change' }
          ],
          date1: [
            { type: 'date', required: true, message: '请选择日期', trigger: 'change' }
          ],
          date2: [
            { type: 'date', required: true, message: '请选择时间', trigger: 'change' }
          ],
          type: [
            { type: 'array', required: true, message: '请至少选择一个活动性质', trigger: 'change' }
          ],
          resource: [
            { required: true, message: '请选择活动资源', trigger: 'change' }
          ],
          desc: [
            { required: true, message: '请填写活动形式', trigger: 'blur' }
          ]
        }
      };
    },
    methods: {
      isRules(val) {
        if(val === '1') {
          this.rules.test = [
            { required: true, message: '请选择测试', trigger: 'change' }
          ]
          this.rules = JSON.parse(JSON.stringify(this.rules))
        } else {
          this.rules.test = null
          this.rules = JSON.parse(JSON.stringify(this.rules))
        }
      },
      submitForm(formName) {
        this.$refs[formName].validate((valid) => {
          if (valid) {
            alert('submit!');
          } else {
            console.log('error submit!!');
            return false;
          }
        });
      },
      resetForm(formName) {
        this.$refs[formName].resetFields();
      }
    }
  }
</script>

想要动态添加校验规则

this.rules.test = [
 
            { required: true, message: '请选择测试', trigger: 'change' }
 
          ]
 
          this.rules = JSON.parse(JSON.stringify(this.rules))

 this.rules = JSON.parse(JSON.stringify(this.rules))必须这样或者用扩展运算符进行重新赋值，才能添加到规则里，并且展示出来，直接将校验规则添加进去，是不会被直接渲染出来的

但是这么写，你会发现，当选完区域一后，会直接触发类似于兜底验证

如图

 会把其他的校验都给触发了，所以可能你会想到在这些代码后直接使用element-UI自带的this.$refs[formName].clearValidate();

但是你会发现并不起效果

所以这时候就需要vue中的$nextTick上场了

this.$nextTick(() => {
            this.$refs.ruleForm.clearValidate();
          })

$nextTick大家应该都理解这个的作用， 大概就是内的代码会在当下一次DOM循环的时候执行

此时就解决了这个问题

原文链接:https://blog.csdn.net/m0_57482145/article/details/121396624