Angular2:电子邮件已经作为自定义验证器存在?

Angular2: email already exist as custom Validator?

我使用 Angular2 创建了一个表单,并创建了以下方法来检查电子邮件地址是否已经存在。这是我的代码:

checkEmail(): void {
    // FIRST PART
    this.found = false;
    // If user is not Premium...
    if (!this.currentUser.isPremium) {
        //  ...and if user typed something in the input field, then apply validitor for email address
        if (this.myForm.controls.email.value.length > 0) {
            this.myForm.controls.email.setValidators([validateEmail()]);
            this.myForm.controls.email.updateValueAndValidity();
        // If user leaves the input field blank or empty the typed input, then apply validator for required
        } else {
            this.myForm.controls.email.setValidators([Validators.required]);
            this.myForm.controls.email.updateValueAndValidity();
        }
    // If user is Premium...
    } else if (this.currentUser.isPremium) {
        // ...and if user typed something in the input field, then apply validitor for email address
        if (this.myForm.controls.email.value.length > 0) {
            this.myForm.controls.email.setValidators([validateEmail()]);
            this.myForm.controls.email.updateValueAndValidity();
        // If user leaves the input field blank or empty the typed input, then remove any validator
        } else {
            this.myForm.controls.email.setValidators(null);
            this.myForm.controls.email.updateValueAndValidity();
        }
    }

    // SECOND PART
    // If the input field is valid then check if the email already exist on server...
    if (this.myForm.controls.email.value.length > 0 && this.myForm.controls.email.valid) {
        this.loadingIcon = true;
        this.anagraficaService.getEmail(this.myForm.controls.email.value)
            .then(response => {
                let count = response.recordCount;
                if (count > 0) {
                    this.found = true;
                } else {
                    this.found = false;
                }
                this.loadingIcon = false;
            })
            .catch(error => {
                this.found = false;
                this.loadingIcon = false;
            });
    }
}

为了启用模板文件中的提交按钮,我检查 myForm.valid 并将 found 设置为 false:

<button type="submit" class="ui primary button" (click)="onSubmit()" [disabled]="!myForm.valid || found">Submit</button>

现在,我想检查电子邮件地址是否已经存在,我的意思是将代码的第二部分放在外部文件(自定义验证程序)中,然后仅在我的第一部分中检查电子邮件地址的有效性代码。像这样:

this.myForm.controls.email.setValidators([validateEmail(), checkEmailExists()]);
this.myForm.controls.email.updateValueAndValidity();

您是否有更好的想法来达到相同的验证?关于这个问题有什么最佳实践吗?

谢谢。

哇。这与反应式表单验证的想法相去甚远。

首先不要这样做

this.myForm.controls.email.setValidators([validateEmail()]);
this.myForm.controls.email.updateValueAndValidity();

setValidatorsupdateValueAndValidity 是您几乎不应该调用的函数。它们仅适用于某些特定情况,例如动态表单行为。

在你的情况下,你有一个静态表单,你应该 describe 与一些验证器。创建自定义异步验证器并将其分配给 email FormControl。这个验证器应该 return 一个 Observable(或 Promise),它在一切正常时解析为 null 或有错误的对象,例如{ emailAlreadyExists: true } 如果电子邮件存在,{ required: true } 或使用 Validators.required 和自定义异步验证的组合。

归根结底你应该

...
public ngOnInit() {
  this.myForm = new FormGroup({
    email: new FormControl('', null, (control: FormControl) => {
      return new Promise((resolve, reject) => {
        // also add here is premium logic
        let requiredValidationResult = Validators.required(control);

        if (requiredValidationResult) {
          resolve(requiredValidationResult); // this will be {required: true}
          return;
        }

        // and here call your server and call
        //   resolve(null) in case it's fine
        //   resolve({ emailExists: true }) in case it's existing
      });
    })
  });
}
...

就是这样。