Angular FormArray | Aprenda sobre Angular FormArray com Exemplo

O FormArrayé uma forma de gerenciar a coleção de controles de formulário no Angular. Os controles podem ser um FormGroup, FormControlou outro FormArray.

Podemos agrupar controles de formulário em formas angulares de duas maneiras. Um está usando o FormGroupe o outro está FormArray. A diferença é como eles o implementam. Em FormGroupcontroles torna-se propriedade de FormGroup. Cada controle é representado como um par de valores-chave. Enquanto em FormArray, os controles se tornam parte de uma matriz

Por ser implementado como um Array, é mais fácil adicionar controles dinamicamente.

Exemplo de FormArray

Vamos construir um aplicativo simples, que nos permite adicionar a nova habilidade de uma pessoa de forma dinâmica.

Importar FormArray

Para usar FormArray, primeiro, você precisa importar o FormArraydo Módulo de Formulários Angular.

import { FormGroup, FormControl,FormArray, FormBuilder } from '@angular/forms'

Construir um modelo de formulário

Construa um modelo de formulário skillsFormusando o FormBuilder. Nosso formulário possui dois campos. nameda pessoa e dele skills. Uma vez que a pessoa pode ter mais de uma habilidade, definimos skillscomo FormArray.

skillsForm: FormGroup;
 
  constructor(private fb:FormBuilder) {
 
    this.skillsForm = this.fb.group({
      name: '',
      skills: this.fb.array([]) ,
    });
  
  }

Em seguida, um gettermétodo skills, que retorna o skillsFormArray doskillsForm

get skills() : FormArray {
  return this.skillsForm.get("skills") as FormArray
}

A habilidade FormGroup

Precisamos capturar dois campos em cada habilidade. Nome dos skill& anos de exp. Portanto, criamos um FormGroupcom dois campos. O método newSkillcria um novo FormGroupe o retorna. Observe que não poderemos atribuir um nome ao Grupo de formulários.

newSkill(): FormGroup {
   return this.fb.group({
     skill: '',
     exp: '',
   })
}

Adicionando habilidade dinamicamente

Agora, precisamos adicionar uma nova habilidade ao skillsFormArray. Como é um array, podemos usar o pushmétodo para adicionar a nova habilidade usando o newSkillmétodo. Observe que o newSkill()método retorna a FormGroup. O nome de FormGroupé seu índice no FormArray.

addSkills() {
   this.skills.push(this.newSkill());
}

Removendo habilidades dinamicamente

Use o removeAtmétodo para remover o elemento do skillsFromArray.

removeSkill(i:number) {
  this.skills.removeAt(i);
}

Enviar

onSubmit() {
   console.log(this.skillsForm.value);
 }

Modelo

Agora é hora de construir o modelo. Use o [formGroup]="skillsForm"para vincular o formulário ao skillsFormmodelo. A formControlName="name"diretiva vincula o nameelemento de entrada à namepropriedade doskillsForm

<form [formGroup]="skillsForm" (ngSubmit)="onSubmit()">
 
  <p>
    <label for="name">Name </label>
    <input type="text" id="name" name="name" formControlName="name">
  </p>
 
 <p>
    <button type="submit">Submit</button>
  </p>
 
</form>

Vinculando FormArray ao Modelo

Usamos a formArrayNamediretiva para vincular o skillsarray do formulário ao divelemento. Agora, o dive qualquer coisa dentro do divelemento está vinculado ao skillsarray do formulário.

<div formArrayName="skills">
 
</div>

Dentro do divuse ngForpara percorrer cada elemento de skillsFormArray. let i=indexirá armazenar o indexvalor do array na variável local do template i. Faremos uso dele para remover o elemento do skillsarray.

<div formArrayName="skills">
  <div *ngFor="let skill of skills().controls; let i=index">
 
  </div>
</div>

Cada elemento sob o skillsé um FormGroup. Não temos um nome para o FormGroup. O Índice do elemento é atribuído automaticamente como o nome do elemento.

Portanto, usamos o [formGroupName]="i"where ié o índice do FormArray para vincular o FormGroupao divelemento.

<div formArrayName="skills">
  <div *ngFor="let skill of skills().controls; let i=index">
      <div [formGroupName]="i">
      
      </div>
  </div>
</div>

Finalmente, adicionamos os controles usando a formControlNamediretiva.

Skills:
  <div formArrayName="skills">
    <div *ngFor="let skill of skills().controls; let i=index">
      <div [formGroupName]="i">
        {{i}}
        skill name :
        <input type="text" formControlName="skill">
        exp:
        <input type="text" formControlName="exp">
 
        <button (click)="removeSkill(i)">Remove</button>
      </div>
    </div>
  </div>

Além disso, passe o índice ipararemoveSkill

<button (click)="removeSkill(i)">Remove</button>

Finalmente, chame o addSkillsmétodo para adicionar novas habilidades.

<p>
  <button type="button" (click)="addSkills()">Add</button>
</p>

É isso
Exemplo de FormArray Angular

Angular FormArray Exemplo em execução de aplicativo

Código fonte

app.component.ts

import { Component, ViewChild, ElementRef } from '@angular/core';
import { FormGroup, FormControl,FormArray, FormBuilder } from '@angular/forms'
 
 
@Component({
  selector: 'app-root',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css']
})
export class AppComponent  {
  
  title = 'FormArray Example in Angular Reactive forms';
 
  skillsForm: FormGroup;
 
  constructor(private fb:FormBuilder) {
 
    this.skillsForm = this.fb.group({
      name: '',
      skills: this.fb.array([]) ,
    });
  
  }
 
  get skills() : FormArray {
    return this.skillsForm.get("skills") as FormArray
  }
 
  newSkill(): FormGroup {
    return this.fb.group({
      skill: '',
      exp: '',
    })
  }
 
  addSkills() {
    this.skills.push(this.newSkill());
  }
 
  removeSkill(i:number) {
    this.skills.removeAt(i);
  }
 
  onSubmit() {
    console.log(this.skillsForm.value);
  }
 
}
 
 
export class country {
  id: string;
  name: string;
 
  constructor(id: string, name: string) {
    this.id = id;
    this.name = name;
  }
}

app.component.html

<form [formGroup]="skillsForm" (ngSubmit)="onSubmit()">
 
  <p>
    <label for="name">Name </label>
    <input type="text" id="name" name="name" formControlName="name">
  </p>
 
 
  Skills:
  <div formArrayName="skills">
    <div *ngFor="let skill of skills().controls; let i=index">
      <div [formGroupName]="i">
        {{i}}
        skill name :
        <input type="text" formControlName="skill">
        exp:
        <input type="text" formControlName="exp">
 
        <button (click)="removeSkill(i)">Remove</button>
      </div>
    </div>
  </div>
 
  <p>
    <button type="submit">Submit</button>
  </p>
 
</form>
 
 
<p>
  <button type="button" (click)="addSkills()">Add</button>
</p>
 
{{this.skillsForm.value | json}}

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Christa  Stehr

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Install Angular - Angular Environment Setup Process

Angular is a TypeScript based framework that works in synchronization with HTML, CSS, and JavaScript. To work with angular, domain knowledge of these 3 is required.

  1. Installing Node.js and npm
  2. Installing Angular CLI
  3. Creating workspace
  4. Deploying your First App

In this article, you will get to know about the Angular Environment setup process. After reading this article, you will be able to install, setup, create, and launch your own application in Angular. So let’s start!!!

Angular environment setup

Install Angular in Easy Steps

For Installing Angular on your Machine, there are 2 prerequisites:

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Node.js

First you need to have Node.js installed as Angular require current, active LTS or maintenance LTS version of Node.js

Download and Install Node.js version suitable for your machine’s operating system.

Npm Package Manager

Angular, Angular CLI and Angular applications are dependent on npm packages. By installing Node.js, you have automatically installed the npm Package manager which will be the base for installing angular in your system. To check the presence of npm client and Angular version check of npm client, run this command:

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Installing Angular CLI

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installing angular CLI

· After executing the command, Angular CLI will get installed within some time. You can check it using the following command

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Workspace Creation

Now as your Angular CLI is installed, you need to create a workspace to work upon your application. Methods for it are:

  • Using CLI
  • Using Visual Studio Code
1. Using CLI

To create a workspace:

  • Navigate to the desired directory where you want to create your workspace using cd command in the Terminal/Command prompt
  • Then in the directory write this command on your terminal and provide the name of the app which you want to create. In my case I have mentioned DataFlair:
  1. Ng new YourAppName

create angular workspace

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angular CSS options

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Angular is a Typescript-based open-source front-end web application platform. The Angular Team at Google and a community of individuals and corporations lead it. Angular lets you extend HTML’s syntax to express your apps’ components clearly. The angular resolves challenges while developing a single page and cross-platform applications. So, here the meaning of the single-page applications in angular is that the index.html file serves the app. And, the index.html file links other files to it.

We build angular applications with basic concepts which are NgModules. It provides a compilation context for components. At the beginning of an angular project, the command-line interface provides a built-in component which is the root component. But, NgModule can add a number of additional components. These can be created through a template or loaded from a router. This is what a compilation context about.

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})

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declarations: [
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  AppRoutingModule,
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],
bootstrap: [AppComponent]
})

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Please watch this video. I hope this video would be helpful for you to understand it and use it in your projects

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