Element-UI 动态设置form验证规则

问题：选择switch 改变 ruleForm.delivery 的值，动态实现校验生效

1、去除rules中需要动态校验的字段规则

// 去除前
rules: {
  name: [
    { required: true,message: "请输入名称",trigger: "blur" }
  ],
  region: [
    { required: true, message: "请选择条件", trigger: "blur" }
  ]
}
// 去除后
rules: {
  name: [
    { trigger: "blur" }
  ],
  region: [
    { required: true, message: "请选择条件", trigger: "blur"  }
  ]
}

2、在prop字段为name的form-item上，添加required属性

下面代码isHaveTo为新字段，根据下拉框选择的值来决定是为true还是false

<el-form-item label="名称" prop="name" :required="isHaveTo">
  <el-input v-model="ruleForm.name"></el-input>
</el-form-item>

3、计算属性，新增字段isHaveTo

下拉选择框为1是非必填，其他都是必填，包括默认

computed: {
    isHaveTo: function() {
      return this.ruleForm.region !== 1;
    }
  },

4、设置错误提示,使用自定义函数控制流程,把name字段重新加回去rules

注意是函数

data() {
    // 验证名称的函数
    let validateName = (rule, value, callback) => {
      // 当名称为空值且为必填时，抛出错误，反之通过校验
      if (this.ruleForm.name === "" && this.isHaveTo) {
        callback(new Error("请输入名称"));
      } else {
        callback();
      }
    };
    return {
      ruleForm: {
        name: "",
        region: ""
      },
      rules: {
        name: [{trigger: "blur" , validator: validateName }],
        region: [
          { required: true, message: "请选择条件", trigger: "blur" }
        ]
      }
    };
  },

自定义函数validator在 return 之前

vue代码：

<template>
  <div>
    <el-form
      :model="ruleForm"
      :rules="rules"
      ref="ruleForm"
      label-width="100px"
      class="demo-ruleForm"
    >
      <el-form-item label="名称" prop="name" :required="isHaveTo">
        <el-input v-model="ruleForm.name"></el-input>
      </el-form-item>
      <el-form-item label="条件" prop="region">
        <el-select v-model="ruleForm.region" placeholder="请选择条件" style="width:100%">
          <el-option label="必填" value="0"></el-option>
          <el-option label="非必填" value="1"></el-option>
        </el-select>
      </el-form-item>
      <el-form-item>
        <el-button type="primary" @click="submitForm('ruleForm')">立即创建</el-button>
      </el-form-item>
    </el-form>
  </div>
</template>
 
<script>
export default {
  name: "HelloWorld",
  data() {
    // 验证名称的函数
    let validateName = (rule, value, callback) => {
      // 当名称为空值且为必填时，抛出错误，反之通过校验
      if (this.ruleForm.name === "" && this.isHaveTo) {
        callback(new Error("请输入名称"));
      } else {
        callback();
      }
    };
    return {
      ruleForm: {
        name: "",
        region: ""
      },
      rules: {
        name: [{ trigger: "blur",validator: validateName }],
        region: [
          { required: true, message: "请选择条件", trigger: "blur" }
        ]
      }
    };
  },
  computed: {
    isHaveTo: function() {
      return this.ruleForm.region !== 1;
    }
  },
  methods: {
    submitForm(formName) {
      this.$refs[formName].validate(valid => {
        if (valid) {
          console.log(`已提交表单`);
        } else {
          console.log("error submit!!");
          return false;
        }
      });
    }
  }
};
</script>