Question

我使用模板驱动的方法在Angular 2中构建表单，并且我已经成功创建了可以在模板中使用的自定义验证器。

但是，我找不到一种方法来显示绑定到特定错误的特定错误消息。我想区分为什么表单无效。我该怎么做？

        import { Component } from '@angular/core';

    import { NgForm } from '@angular/forms';

    import { Site } from './../site';

    import { BackendService } from './../backend.service';

    import { email } from './../validators';

    import { CustomValidators } from './../validators';

    @Component({
        templateUrl: 'app/templates/form.component.html',
        styleUrls: ['app/css/form.css'],
        directives: [CustomValidators.Email, CustomValidators.Url, CustomValidators.Goof],
        providers: [BackendService]
    })

    export class FormComponent {
        active = true;
        submitted = false;
        model = new Site();

        onSubmit() {
            this.submitted = true;
            console.log(this.model);
        }

        resetForm() {
            this.model = new Site();
            this.submitted = false;
            this.active = false;
            setTimeout(() => this.active = true, 0);
        }

        get diagnostics() {
            return JSON.stringify(this.model)
        }
    }

import { Directive, forwardRef } from '@angular/core';
import { NG_VALIDATORS, FormControl } from '@angular/forms';
import { BackendService } from './backend.service';

function validateEmailFactory(backend:BackendService) {
    return (c:FormControl) => {
        let EMAIL_REGEXP = /^[a-z0-9!#$%&'*+\/=?^_`{|}~.-]+@[a-z0-9]([a-z0-9-]*[a-z0-9])?(\.[a-z0-9]([a-z0-9-]*[a-z0-9])?)*$/i;

        return EMAIL_REGEXP.test(c.value) ? null : {
            validateEmail: {
                valid: false
            }
        };
    };
}

export module CustomValidators {

    @Directive({
        selector: '[email][ngModel],[email][formControl]',
        providers: [
            {provide: NG_VALIDATORS, useExisting: forwardRef(() => CustomValidators.Email), multi: true}
        ]
    })
    export class Email {
        validator:Function;

        constructor(backend:BackendService) {
            this.validator = validateEmailFactory(backend);
        }

        validate(c:FormControl) {
            return this.validator(c);
        }
    }

    @Directive({
        selector: '[url][ngModel],[url][formControl]',
        providers: [
            {provide: NG_VALIDATORS, useExisting: forwardRef(() => CustomValidators.Url), multi: true}
        ]
    })
    export class Url {
        validator:Function;

        constructor(backend:BackendService) {
            this.validator = validateEmailFactory(backend);
        }

        validate(c:FormControl) {
            var pattern = /(https?:\/\/)?(www\.)?[-a-zA-Z0-9@:%._\+~#=]{2,256}\.[a-z]{2,4}\b([-a-zA-Z0-9@:%_\+.~#?&//=]*)/;

            return pattern.test(c.value) ? null : {
                validateEmail: {
                    valid: false
                }
            };
        }
    }

    @Directive({
        selector: '[goof][ngModel],[goof][formControl]',
        providers: [
            {provide: NG_VALIDATORS, useExisting: forwardRef(() => CustomValidators.Goof), multi: true}
        ]
    })
    export class Goof {
        validate(c:FormControl) {
            return {
                validateGoof: {
                    valid: false
                }
            };
        }
    }
}

Answer 1

您可以检查AbstractControl#hasError(...)方法以查看控件是否有特定错误。 FormGroup和FormControl都是AbstractControl。对于FormControl，您只需将错误名称作为参数传递。例如

function regexValidator(control: FormControl): {[key:string]: boolean} {
  if (!control.value.match(/^pee/)) {
    return { 'badName': true };
  }
}

<div *ngIf="!nameCtrl.valid && nameCtrl.hasError('badName')"
     class="error">Name must start with <tt>pee</tt>.
</div>

验证器方法应该返回一个字符串/布尔映射，其中键是错误的名称。这是您在hasError方法中检查的名称。

对于FormGroup，您可以将FormControl的路径作为额外参数传递。

<div *ngIf="!form.valid && form.hasError('required', ['name'])"
     class="error">Form name is required.</div>

name只是输入FormControl的标识符。

以下是FormControl和FormGroup检查的示例。

import { Component } from '@angular/core';
import {
  FormGroup,
  FormBuilder,
  FormControl,
  Validators,
  AbstractControl,
  REACTIVE_FORM_DIRECTIVES
} from '@angular/forms';

function regexValidator(control: FormControl): {[key:string]: boolean} {
  if (!control.value.match(/^pee/)) {
    return { 'badName': true };
  }
}

@Component({
  selector: 'validation-errors-demo',
  template: `
    <div>
      <h2>Differentiate Validation Errors</h2>
      <h4>Type in "peeskillet"</h4>
      <form [formGroup]="form">
        <label for="name">Name: </label>
        <input type="text" [formControl]="nameCtrl"/>
        <div *ngIf="!nameCtrl.valid && nameCtrl.hasError('required')"
             class="error">Name is required.</div>
        <div *ngIf="!nameCtrl.valid && nameCtrl.hasError('badName')"
             class="error">Name must start with <tt>pee</tt>.</div>
        <div *ngIf="!form.valid && form.hasError('required', ['name'])"
             class="error">Form name is required.</div>
      </form>
    </div>
  `,
  styles: [`
    .error {
      border-radius: 3px;
      border: 1px solid #AB4F5B;
      color: #AB4F5B;
      background-color: #F7CBD1;
      margin: 5px;
      padding: 10px;
    }
  `],
  directives: [REACTIVE_FORM_DIRECTIVES],
  providers: [FormBuilder]
})
export class ValidationErrorsDemoComponent {
  form: FormGroup;
  nameCtrl: AbstractControl;

  constructor(formBuilder: FormBuilder) {
    let name = new FormControl('', Validators.compose([
      Validators.required, regexValidator
    ]));
    this.form = formBuilder.group({
      name: name
    });
    this.nameCtrl = this.form.controls['name'];
  }
}

更新

好的，所以我让它运转了，但它有点冗长。我无法弄清楚如何正确访问输入的单个FormControl。所以我所做的只是创建对FormGroup

的引用

<form #f="ngForm" novalidate>

然后检查有效性，我只使用传递了表单控件名称路径的hasError重载。对于使用<input>和name的{{1}}，ngModel值会添加到主name，其名称为FormGroup。所以你可以像

那样访问它

FormControl

假设`f.form.hasError('require', ['nameCtrl'])`。请注意name=nameCtrl。 f.form是f个实例，其NgForm成员变量为FormGroup。

以下是重构的例子

form

Answer 2

我在AngularJs中编写了一组类似于ng-messages的指令来解决Angular中的这个问题。 https://github.com/DmitryEfimenko/ngx-messages

<div [val-messages]="myForm.get('email')">
  <span val-message="required">Please provide email address</span>
  <span val-message="server" useErrorValue="true"></span>
</div>

Answer 3

对于模板驱动验证，请使用如下属性指令：

import { Model } from '../../models';
import { Directive, Attribute, forwardRef, Input } from '@angular/core';
import { NG_VALIDATORS, Validator, AbstractControl } from '@angular/forms';

@Directive({
    selector: '[unique-in-list][formControlName],[unique-in-list][formControl],[unique-in-list][ngModel]',
    providers: [
        { provide: NG_VALIDATORS, useExisting: forwardRef(() => UniqueInListDirectiveValidator), multi: true }
    ]
})
export class UniqueInListDirectiveValidator implements Validator {
     @Input('list') private list: Model[];
     @Input('property') private _property: string;
     @Input('thisid') private _myId: string;

     validate(control: AbstractControl): { [key: string]: any } {

        let currValue = control.value;
        if (currValue && currValue.length > 0 && this.list && Array.isArray(this.list) && this.list.length > 0) {
            let model = this.list.find(
                (testModel: Model) => {
                    return testModel.modelId !== this._myId && testModel[this._property] === currValue;
                }
            );
            if (model) {
                return { isUnique: true }
            }
        }
        return null;
    }
}

..并在模板中附带标记：

<input
    type="text"
    #nameVar="ngModel"
    name="name"
    class="form-control name-field"
    unique-in-list
    [list]="models"
    [thisid]="model.modelId"
    property="name"
    [(ngModel)]="model.name"
    required
/>
<div *ngIf="nameVar.errors?.required && (submitted || !nameVar.pristine)" class="alert-classes-here">
    <div>Name is required</div>
</div>
<div *ngIf="nameVar.errors?.isUnique && (submitted || !nameVar.pristine)" class="alert-classes-here">
    <div>Name is already taken</div>
</div>

HTH

如何根据Angular 2中的自定义验证规则显示错误消息？

3 个答案:

更新