注：本文的demo实现都是用了笔者自己搭建的vue、react的初始化demo项目，方便平时做实现，写demo用。每次都要从0搭建实在是太恶心了，如果大家也用得上，直接clone走。

react-demo(create-react-app@1.5.2 + antd@3.6.4 + react@16.4.1 + react-router-dom@4.3.1)

vue-demo(vue-cli@2.9.3 + element-ui@2.4.1 + vue@2.5.2 + vue-router@3.0.1)

表单复杂校验规则的一个demo说明

姓名：

1. 必填
2. 最多5个字符
3. 不能与【父亲姓名】一致

昵称：

1. 必填
2. 最多3个字符
3. 【姓名】修改会触发此字段修改，截取【姓名】的前三个字符
4. 可自己修改

父亲姓名：

1. 必填
2. 最多5个字符
3. 不能与【姓名】一致

vue（ElementUI）实现：

<template>
  <div class="formvalidate">
    <p>实现表单的关联校验</p>
    <el-row>
      <el-col :span="12">
        <el-form :model="ruleForm" :rules="rules" ref="ruleForm" label-width="100px">
          <el-form-item label="姓名" prop='name'>
            <el-input v-model="ruleForm.name"></el-input>
            <p class="note">请输入最多5个字符，且不能和父亲姓名一样</p>
          </el-form-item>
          <el-form-item label="昵称" prop='nick' required>
            <el-input v-model="nickName"></el-input>
            <p class="note">请输入最多3个字符</p>
          </el-form-item>
          <el-form-item label="父亲姓名" prop='father'>
            <el-input v-model="ruleForm.father"></el-input>
            <p class="note">请输入最多5个字符，且不能和子女姓名一样</p>
          </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>
        <pre>{{result}}</pre>
      </el-col>
    </el-row>
  </div>
</template>

<script>
export default {
  name: 'FormValidate',
  data() {
    return {
      ruleForm: {
        name: '',
        nick: '',
        father: '',
      },
      result: '',
      rules: {
        name: [
          { required: true, message: '请输入内容', trigger: 'change' },
          { max: 5, message: '最多5个字符', trigger: 'change' },
          { validator: (rule, value, callback) => { // ======划重点======
            if (value === this.ruleForm.father) {
              callback(new Error('不能与父亲姓名一致'));
            } else {
              callback();
            }
          }, trigger: 'change' },
        ],
        nick: [
          { required: true, message: '请输入内容', trigger: 'change' },
          { max: 3, message: '最多3个字符', trigger: 'change' },
        ],
        father: [
          { required: true, message: '请输入内容', trigger: 'change' },
          { max: 5, message: '最多5个字符', trigger: 'change' },
          { validator: (rule, value, callback) => { // ======划重点======
            if (value === this.ruleForm.name) {
              callback(new Error('不能与姓名一致'));
            } else {
              callback();
            }
          }, trigger: 'change' },
        ],
      },
    }
  },
  computed: { // ======划重点======
    nickName:{
      set(value){
        this.ruleForm.nick = value;
      },
      get(){
        const val = this.ruleForm.name.substring(0,3);
        this.ruleForm.nick = val;
        return val;
      },
    }
  },
  methods: {
    submitForm(formName) {
      this.$refs[formName].validate((valid) => {
        if (valid) {
          this.result = JSON.stringify(this.ruleForm,null,2);
        } else {
          return false;
        }
      });
    },
    resetForm(formName) {
      this.$refs[formName].resetFields();
    },
  },
};
</script>

<style scoped>
.note {
  line-height: 1;
  color: #999;
  font-size: 12px;
  margin: 10px 0 0;
}
</style>

注：element的官方文档推荐了async-validator作为rules规则的文档参考，笔者还没有详细研究，猜测element用了此库。另外antd的验证规则格式也是这个样子的，所以也有用了这个库的可能。想要自己实现一套form校验规则的同学，可以研究一下。

react（antd）实现：

import React, { Component } from 'react';
import { Form, Input, Button } from 'antd';
import './style.less';

const FormItem = Form.Item;
const formItemLayout = {
  labelCol: { span: 4 },
  wrapperCol: { span: 8 },
};
const formTailLayout = {
  labelCol: { span: 4 },
  wrapperCol: { span: 8, offset: 4 },
};

class FormValidate extends Component {
  changeName(value) {
    this.props.form.setFieldsValue({ nick: value.substring(0, 3) });
  }

  render() {
    const { getFieldDecorator } = this.props.form;
    return (
      <div className="FormValidate">
        <h1>实现表单的关联校验</h1>
        <Form>
          <FormItem {...formItemLayout} label='姓名' extra='请输入最多5个字符，且不能和父亲姓名一样'>
            {getFieldDecorator('name', {
              rules: [
                { required: true, message: '请输入内容', trigger: 'change' },
                { max: 5, message: '最多5个字符', trigger: 'change' },
                {
                  validator: (rule, value, callback) => { // ======划重点======
                    const form = this.props.form;
                    if (value && value === form.getFieldValue('father')) {
                      callback('不能与父亲姓名一致');
                    } else {
                      callback();
                    }
                  }, trigger: 'change'
                },
              ],
            })(<Input placeholder="Please input your name" onChange={e => this.changeName(e.target.value)} />)}
          </FormItem>
          <FormItem {...formItemLayout} label='昵称' extra='请输入最多3个字符'>
            {getFieldDecorator('nick', {
              rules: [
                { required: true, message: '请输入内容', trigger: 'change' },
                { max: 3, message: '最多3个字符', trigger: 'change' },
              ],
            })(<Input placeholder="Please input your name" />)}
          </FormItem>
          <FormItem {...formItemLayout} label='父亲姓名' extra='请输入最多5个字符，且不能和子女姓名一样'>
            {getFieldDecorator('father', {
              rules: [
                { required: true, message: '请输入内容', trigger: 'change' },
                { max: 5, message: '最多5个字符', trigger: 'change' },
                {
                  validator: (rule, value, callback) => { // ======划重点======
                    const form = this.props.form;
                    if (value && value === form.getFieldValue('name')) {
                      callback('不能与姓名一致');
                    } else {
                      callback();
                    }
                  }, trigger: 'change'
                },
              ],
            })(<Input placeholder="Please input your name" />)}
          </FormItem>
          <FormItem {...formTailLayout}>
            <Button type="primary">提交</Button>
          </FormItem>
        </Form>
      </div>
    );
  }
}

export default Form.create()(FormValidate);