Angular自定义表单验证

前端表单验证

为年龄输入框添加了两个验证，并分情况填写了提示语

<form nz-form [formGroup]="validateForm">
  <nz-form-item>
    <nz-form-label [nzSpan]="3" nzRequired>年龄</nz-form-label>
    <nz-form-control [nzSpan]="8" nzHasFeedback>
      <input nz-input formControlName="age" placeholder="请输入年龄">
      <nz-form-explain *ngIf="validateForm.get('age').dirty && validateForm.get('age').errors">
        <ng-container *ngIf="validateForm.get('age').hasError('required')">请输入年龄</ng-container>
        <!--自定义验证  注意加单引号-->
        <ng-container *ngIf="validateForm.get('age').hasError('isMoreThanZero')">年龄必须为数字，且大于等于0</ng-container>
      </nz-form-explain>
    </nz-form-control>
  </nz-form-item>
</form>

[Validators.required, this.isMoreThanZero]为age字段的验证列表
其中Validators.required是Validators提供的验证，this.isMoreThanZero是自定义验证

this.validateForm = this.fb.group({
    age: [null, [Validators.required, this.isMoreThanZero]], // 年龄
});

自定义isMoreThanZero的验证规则

/**
 * @description  自定义表单验证:是数字并且大于等于0
 */
isMoreThanZero = (control: FormControl) => {
    if (!control.value) {
        return { required: true };
    } else if (isNaN(Number(control.value)) || control.value < 0) {
        // 注意，这里返回的是isMoreThanZero，才能对应.hasError('isMoreThanZero')
        return {  isMoreThanZero: true };
    }
}

后端表单验证

比如，业务要求编码不重复，查询编码是否存在
设置一个叫做existSameCode的验证，当existSameCode=true，则验证失败

<nz-form-item>
    <nz-form-label [nzSpan]="3" nzRequired>编码</nz-form-label>
    <nz-form-control [nzSpan]="8" nzHasFeedback>
      <input nz-input formControlName="code" placeholder="请输入编码">
      <!--表单验证-->
      <nz-form-explain *ngIf="validateForm.get('code').dirty && validateForm.get('code').errors">
        <ng-container *ngIf="validateForm.get('code').hasError('required')">请输入编码</ng-container>
        <ng-container *ngIf="validateForm.get('code').hasError('existSameCode')">已存在相同编码</ng-container>
      </nz-form-explain>
    </nz-form-control>
</nz-form-item>

设置表单验证
Tip:[默认值,[同步校验],[异步校验]]
这里this.checkData是异步校验，所以写到第三个参数的位置

this.validateForm = this.fb.group({
    code: [null, [Validators.required], [this.checkData]], // 编码
});

调用testService的方法，异步查询结果

/**
 * @description  自定义表单验证:查询编码是否重复
 */
checkData: AsyncValidatorFn = (control: FormControl): Promise<ValidationErrors | null> =>{
    return new Promise((resolve2) => {
        setTimeout(() => {
            this.testService.checkData({code:control.value})
                .then((response: any) => {
                    if (response) {
                        resolve2({existSameCode: true});
                    } else {
                        resolve2(null);
                    }
                });
        }, 1500);
    });
}

如果存在，返回true，不存在，返回false

checkData(params): Promise<any> {
    // 这里可以调用服务，验证是否存在相同编码
    // 例子简化为前端验证
    const pRequest =new Promise(function(resolve, reject) {
        let existCodeList=['1','2','3'];
        if(existCodeList.indexOf(params.code) > -1){
            resolve(true);
        }
        resolve(false);
    }).then((ret: any) => {
        return ret;
    });

    return Promise.race([this.requestHelperService.getTimeoutPromise(), pRequest]).catch(ret => {
        this.requestHelperService.handleRequestError(ret, true);
    });
}

示例代码

https://github.com/zLulus/NotePractice/tree/dev3/Website/DotNetCore/CoreNgAlain/src/app/routes/data-transfer

参考资料

https://www.angular.cn/api/forms/Validators
http://liubin.org/promises-book/