Angular4表单（模板驱动表单、响应式表单、自定义表单验证）

时间 2019-11-13

标签 angular4 angular 表单模板驱动响应自定义验证栏目 AngularJS 繁體版

原文原文链接

看了两天官网文档表单和表单验证后，才发现以前本身仅仅经过特定的 Angular CSS 类去控制去反馈用户的操做，如ng-touched等等是多么的入门，虽说这已经够用了，可是以前写的都是在视图层上写逻辑，各类判断，致使后期维护有点困难。趁有时间记录一下这两天看了资料的一些心得。javascript

模板驱动表单VS响应式表单

二者均可以经过表单绑定获取整个表单的值和是否合法eg: myForm.value, myForm.valid等等html

Template-Driven Forms (模板驱动表单) 的特色

使用方便java
适用于简单的场景react
经过 [(ngModel)] 实现数据双向绑定json
最小化组件类的代码segmentfault
不易于单元测试数组
导入FormModule函数
表单绑定经过 #myForm="ngForm"单元测试

Reactive Forms (响应式表单) 的特色

比较灵活测试
适用于复杂的场景
简化了HTML模板的代码，把验证逻辑抽离到组件类中
方便的跟踪表单控件值的变化
易于单元测试
导入ReactiveFormsModule
表单绑定经过 [formGroup]="myForm"

组件类代码解释

Template-Driven Forms (模板驱动表单)

import { Component, AfterViewChecked, ViewChild } from '@angular/core';
import { NgForm } from '@angular/forms';
import { Hero }      from '../shared/hero';
@Component({
  selector: 'hero-form-template2',
  templateUrl: './hero-form-template2.component.html'
})
export class HeroFormTemplate2Component implements AfterViewChecked {

  powers = ['Really Smart', 'Super Flexible', 'Weather Changer'];

  hero = new Hero(18, 'Dr. WhatIsHisWayTooLongName', this.powers[0], 'Dr. What');

  submitted = false;

  onSubmit() {
    this.submitted = true;
  }

  // Reset the form with a new hero AND restore 'pristine' class state
  // by toggling 'active' flag which causes the form
  // to be removed/re-added in a tick via NgIf
  // TODO: Workaround until NgForm has a reset method (#6822)
  active = true;

  addHero() {
    this.hero = new Hero(42, '', '');

    this.active = false;
    setTimeout(() => this.active = true, 0);
  }
  /*组件手动记录表单对象*/
  heroForm: NgForm;

  /*heroFrom变量是Angular从模板衍生出来的控制模型的引用。 咱们利用@ViewChild来告诉Angular注入这个模型到组件类的currentForm*/
  @ViewChild('heroForm') currentForm: NgForm;

  /*监听视图中表格变化，第一次渲染表格对象有多少个值就跑多少次*/
  ngAfterViewChecked() {
    this.formChanged();
  }

  formChanged() {
    /*检测是否发生变化*/
    if (this.currentForm === this.heroForm) { return; }
    this.heroForm = this.currentForm;
    if (this.heroForm) {
      /*heroForm获得的是FormModule对象，该对象继承于AbstractControl抽象类，里面包含touched等*/
      /*valueChanges返回一个Observal，用于获取视图返回的可观察对象*/
      this.heroForm.valueChanges
        .subscribe(data => this.onValueChanged(data));
    }
  }

  onValueChanged(data?: any) {
    if (!this.heroForm) { return; }
    const form = this.heroForm.form;

    for (const field in this.formErrors) {
      // clear previous error message (if any)
      this.formErrors[field] = '';
      /*heroForm.form.get('name')获取对应表单里的键值*/
      const control = form.get(field);

      if (control && control.dirty && !control.valid) {
        const messages = this.validationMessages[field];
        for (const key in control.errors) {
          this.formErrors[field] += messages[key] + ' ';
        }
      }
    }
  }

  formErrors = {
    'name': '',
    'power': ''
  };

  validationMessages = {
    'name': {
      'required':      'Name is required.',
      'minlength':     'Name must be at least 4 characters long.',
      'maxlength':     'Name cannot be more than 24 characters long.',
      'forbiddenName': 'Someone named "Bob" cannot be a hero.'
    },
    'power': {
      'required': 'Power is required.'
    }
  };
}

Reactive Forms (响应式表单) 的特色

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

import { Hero }                   from '../shared/hero';
import { forbiddenNameValidator } from '../shared/forbidden-name.directive';

@Component({
  ...
})
export class HeroFormReactiveComponent implements OnInit {

  ...
  /**/
  heroForm: FormGroup;
  constructor(private fb: FormBuilder) { }

  ngOnInit(): void {
    /*初始化表单对象*/
    this.buildForm();
  }

  buildForm(): void {
    /*FormBuilder.group是一个用来建立FormGroup的工厂方法*/
    this.heroForm = this.fb.group({
      /*这里的值接受两个参数，第一个是值，第二个是检验器，若是有多个检验器必须用数组表示*/
      'name': [this.hero.name, [
          Validators.required,
          Validators.minLength(4),
          Validators.maxLength(24),
          forbiddenNameValidator(/bob/i)
        ]
      ],
      'alterEgo': [this.hero.alterEgo],
      'power':    [this.hero.power, Validators.required]
    });

    this.heroForm.valueChanges
      .subscribe(data => this.onValueChanged(data));

    this.onValueChanged(); // (re)set validation messages now
  }

  /*与驱动表单上面代码相似*/
  ...
}

组件视图层对比

Template-Driven Forms (模板驱动表单)

表组经过ngModelGroup去绑定

<form #templateForm="ngForm" novalidate (ngSubmit)="onSubmit(templateForm)">
    <span>Name</span>
    <label class="user_name">
      <input #uName="ngModel" type="text" name="user_name" [(ngModel)]="user.name" required>
    </label>
    <div ngModelGroup="account">
      <span>QQ</span>
      <label class="user_name">
        <input type="text" name="user_qq" [(ngModel)]="user.account.qq" required>
      </label>
      <span>Password</span>
      <label class="user_name">
        <input type="password" name="user_password" [(ngModel)]="user.account.password" required>
      </label>
    </div>
    <button style="width: 200px; height: 36px; border: 1px solid #ccc; margin-top: 20px;" [disabled]="templateForm.invalid">提交</button>
</form>

Reactive Forms (响应式表单) 的特色

表组经过

formGroupName="address"

-------------------------------------------------------------------

自定义表单验证

html:

这里注意要经过表单.get的方法获取FormModel的东西，reactiveForm.get('age').touched 或者reactive.controls.age?.touched

<form [formGroup]="reactiveForm" (ngSubmit)="onSubmit()">
  <div class="form-group">
    <label for="name">Name</label>
    <input type="text" id="name" class="form-control" formControlName="name">
  </div>
  <div class="form-group" [ngClass]="{'has-error': (reactiveForm.get('age').touched || reactiveForm.get('age').dirty) && !reactiveForm.get('age').valid }">
    <label class="col-md-2 control-label" for="ageId">年龄</label>

    <div class="col-md-8">
      <input class="form-control" id="ageId" type="number" placeholder="请输入年龄" formControlName="age" />
      <span class="help-block" *ngIf="(reactiveForm.get('age').touched || reactiveForm.get('age').dirty) && reactiveForm.get('age').errors">
        <span *ngIf="reactiveForm.get('age').errors.range">
            输入年龄不合法
        </span>
      </span>
    </div>
  </div>
  <p>{{reactiveForm.value | json}}</p>
</form>

ts:

...

@Component({
  ...
})
export class ReactiveFormComponent implements OnInit {

  user: any = {
    name: '',
    age: 0
  };

  reactiveForm: FormGroup;

  constructor(public fb: FormBuilder) { }

  ngOnInit() {
    this.buildForm();
  }

  buildForm(): void {
    this.reactiveForm = this.fb.group({
      'name': [this.user.name, Validators.required],
      'age': [this.user.age, this.ageValidator]    //自定义验证方法使用
    });

    // this.reactiveForm.valueChanges
    //   .subscribe(data => { console.log(data) });
  }

  /*有参数的验证器工厂函数写法，这里FormControl和下面的AbstractControl都是指向抽象类的属性和方法都是为了获取表单属性*/
  private ageValidatorParams(min: number, max: number) {
    return (c: FormControl): { [key: string]: any } | null => {
      let age = c.value;
      if (age && (isNaN(age) || age < min || age > max)) {
        return { 'range': true, min: min, max: max };
      }
      return null;
    }
  }
  /*必须返回一个对象，该对象为错误信息的值*/
  private ageValidator(c: AbstractControl): { [key: string]: any } | null {
    let age = c.value;
    if (age && (isNaN(age) || age < 20 || age > 120)) {
      return { 'range': true, min: 20, max: 120 };
    }
    return null;
  }

}

参考文献：

一、Angular官方文档（表单验证）

二、模板驱动式表单

三、响应式表单

四、案例状况比较多的表单验证