Angular8-简单表单验证

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直接复制 Antd 中 demo

<form nz-form [nzLayout]="'inline'" [formGroup]="validateForm" (ngSubmit)="submitForm()">
  <nz-form-item>
    <nz-form-control nzErrorTip="Please input your username!">
      <nz-input-group nzPrefixIcon="user">
        <input formControlName="userName" nz-input placeholder="Username" />
      </nz-input-group>
    </nz-form-control>
  </nz-form-item>
  <nz-form-item>
    <nz-form-control nzErrorTip="Please input your Password!">
      <nz-input-group nzPrefixIcon="lock">
        <input formControlName="password" nz-input type="password" placeholder="Password" />
      </nz-input-group>
    </nz-form-control>
  </nz-form-item>
  <nz-form-item>
    <nz-form-control>
      <button nz-button nzType="primary" [disabled]="!validateForm.valid">Log in</button>
    </nz-form-control>
  </nz-form-item>
</form>

validateForm!: FormGroup;

  submitForm(): void {for (const i in this.validateForm.controls) {this.validateForm.controls[i].markAsDirty();
      this.validateForm.controls[i].updateValueAndValidity();}
  }

  constructor(private fb: FormBuilder) {}

  ngOnInit(): void {
    this.validateForm = this.fb.group({userName: [null, [Validators.required]],
      password: [null, [Validators.required]],
      remember: [true]
    });
  }

此类表单校验较为单一，或者要求比较低，通常即为 required 校验，错误信息提示也多为固定不变。

表单一旦开始有具体的细节校验或者复杂的业务参杂，校验提示必须准确、清晰。
userName为例，除了为必填项，必然需要符合某种格式，亦或是指定邮箱格式等，那么校验必须同时反映出错误类型，本例假设用户名有长度要求进行演示。

<nz-form-control [nzErrorTip]="getErrTipByField('userName')">
      <nz-input-group nzPrefixIcon="user">
        <input formControlName="userName" nz-input placeholder="Username" />
      </nz-input-group>
    </nz-form-control>

export class SimpleFormComponent implements OnInit {
  validateForm: FormGroup;
  errMessageMap = {};

  constructor(private fb: FormBuilder) { }

  ngOnInit() {
    this.errMessageMap = {
      userName: {
        required: 'please input your name!',
        minlength: 'please input at least least 5 character'
      },
      password: {required: 'please input your password!'}
    };
    this.validateForm = this.fb.group({userName: [null, [Validators.required, Validators.minLength(5)]],
      password: [null, [Validators.required]],
      remember: [true]
    }, {updateOn: 'change'});
  }
  submitForm(): void {if (this.validateForm.controls) {for (const i in this.validateForm.controls) {if (this.validateForm.controls[i]) {this.validateForm.controls[i].markAsDirty();
          this.validateForm.controls[i].updateValueAndValidity();}
      }
    }
  }
  getErrTipByField(fieldName) {const errors = this.validateForm.get(fieldName).errors;
    let errMsg = '';
    for (const key in errors) {if (errors.hasOwnProperty(key)) {errMsg += this.errMessageMap[fieldName][key];
      }
    }
    return errMsg;
  }

}

构建出一个数据对象，以满足不同字段下不同错误类型的错误提示，根据业务需求，决定是否显示全部错误信息或者按照业务优先级显示。