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Create CRUD Application Example with REST Web API in Angular

Angular
2322 views 2 years ago
post-title

In this article, I will share with you how to create angule 11 CRUD application with the REST Web API with example. you just follow the steps.

The REST API Endpoints

We'll be building an Angular 11 frontend app for a surmised REST API exporting the following REST API endpoints:

  • POST /api/products engender incipient product
  • GET /api/products retrieve all products
  • GET /api/products/:id retrieve a product by :id
  • PUT /api/products/:id update a product by :id
  • EXPUNGE /api/products/:id expunge a product by :id
  • EFFACE /api/products efface all products
  • GET /api/products?name=[keyword] find all products which designation contains the passed keyword.

All of them can work well with this Angular App.

Angular 11 CRUD App Structure

These are the components of our CRUD app:

The App component is the parent of all other components and contains a router-outlet directive where the router will be inserting any matched component. It withal contains a navigation bar that contains links to the app routes utilizing routerLink directive.
– ProductListComponent which exhibits the list of products.
– ProductUpdateComponent which exhibits a form for editing product’s details by :id.
– ProductCreateComponent which exhibits a form for engendering an incipient product.

The components utilize the ProductService methods for genuinely making CRUD operations against the REST API. The accommodation makes utilization of Angular 11 HTTPClient to send HTTP requests to the REST and process replications.

Step 1: Creating a New Angular 11 Project

Let's get started by generating a new Angular 11 project using the CLI. You need to run the following command:

$ ng new Angular11CRUDExample

The CLI will ask you a couple of questions — If Would you like to add Angular routing? Type y for Yes and Which stylesheet format would you like to use? Choose CSS.

Step 2: Generating Angular 11 CRUD Components and Service

Next, we need to generate a bunch of components and a service using the Angular CLI as follows:

$ ng generate service services/product
$ ng g c components/product-create
$ ng g c components/product-details
$ ng g c components/product-list

We have generated three components product-list, product-details, product-create and a product service that provides the necessary methods for sending HTTP requests to the server.

We also have the following artifacts:

– The src/app/app-routing.module.ts module will contain routes for each component. This file is automatically generated by Angular CLI when you answered Yes for routing. – The App component contains the router view and navigation bar.
– The src/app/app.module.ts module declares our Angular components and import the necessary modules such Angular HttpClient.

Step 3: Importing FormsModule and HttpClientModule

We'll be using the http client and forms in our CRUD application which are provided in its own modules in Angular so we'll need to import these modules — FormsModule and HttpClientModule.

Open src/app/app.module.ts file and import FormsModule, HttpClientModule as follows:

// [...]
import { FormsModule } from '@angular/forms';
import { HttpClientModule } from '@angular/common/http';

@NgModule({
  declarations: [ ... ],
  imports: [
    ...
    FormsModule,
    HttpClientModule
  ],
  providers: [],
  bootstrap: [AppComponent]
})
export class AppModule { }

Step 4: Adding Routes for the CRUD Components

We have the components that compose our application UI but we need to link them with their routes to be able to navigate between them using the Angular 11 Router.

We'll create three routes:

– /products for the product-list component, – /products/:id for the product-details component, – /create for theproduct-create component.

Open the src/app/app-routing.module.ts file and update it as follows:

import { NgModule } from '@angular/core';
import { Routes, RouterModule } from '@angular/router';

import { ProductListComponent } from './components/product-list/product-list.component';
import { ProductDetailsComponent } from './components/product-details/product-details.component';
import { ProductCreateComponent } from './components/product-create/product-create.component';

const routes: Routes = [
  { path: '', redirectTo: 'products', pathMatch: 'full' },
  { path: 'products', component: ProductListComponent },
  { path: 'products/:id', component: ProductDetailsComponent },
  { path: 'create', component: ProductCreateComponent }
];

@NgModule({
  imports: [RouterModule.forRoot(routes)],
  exports: [RouterModule]
})
export class AppRoutingModule { }

Step 5: Adding and Styling a Navigation Bar Using Bootstrap 4

Next, let's add Bootstrap 4 to our application and a navigation bar.

Open the src/app/app.component.html file, and update as follows:

<div>
  <nav class="navbar navbar-expand navbar-dark bg-dark">
    <a href="#" class="navbar-brand">Techiediaries</a>
    <div class="navbar-nav mr-auto">
      <li class="nav-item">
        <a routerLink="products" class="nav-link">Products</a>
      </li>
      <li class="nav-item">
        <a routerLink="create" class="nav-link">Create</a>
      </li>
    </div>
  </nav>

  <div class="container mt-5">
    <router-outlet></router-outlet>
  </div>
</div>

We have created a bootstrap navigation bar and wrapped the router outlet with a container div.

Step 6: Creating an Angular 11 CRUD Service

Next, we need to create a CRUD service that will use Angular 11 HTTPClient to send HTTP requests to the REST API server.

Open the src/services/product.service.ts file and update it as follows:

import { Injectable } from '@angular/core';
import { HttpClient } from '@angular/common/http';
import { Observable } from 'rxjs';

const baseURL = 'http://localhost:8080/api/products';

@Injectable({
  providedIn: 'root'
})
export class ProductService {

  constructor(private httpClient: HttpClient) { }

  readAll(): Observable<any> {
    return this.httpClient.get(baseURL);
  }

  read(id): Observable<any> {
    return this.httpClient.get(`${baseURL}/${id}`);
  }

  create(data): Observable<any> {
    return this.httpClient.post(baseURL, data);
  }

  update(id, data): Observable<any> {
    return this.httpClient.put(`${baseURL}/${id}`, data);
  }

  delete(id): Observable<any> {
    return this.httpClient.delete(`${baseURL}/${id}`);
  }

  deleteAll(): Observable<any> {
    return this.httpClient.delete(baseURL);
  }

  searchByName(name): Observable<any> {
    return this.httpClient.get(`${baseURL}?name=${name}`);
  }
}

Step 7: Implementing the Angular 11 CRUD Components

We have previously generated three components and added them to the router, let's now implement the actual functionality of each component.

Creating a New Product Component

This component provides a form for submitting a new product with two fields, name and description. It injects and calls the ProductService.create() method.

Open the src/components/product-create/product-create.component.ts file and update it as follows:

import { Component, OnInit } from '@angular/core';
import { ProductService } from 'src/app/services/product.service';

@Component({
  selector: 'app-product-create',
  templateUrl: './product-create.component.html',
  styleUrls: ['./product-create.component.css']
})
export class ProductCreateComponent implements OnInit {
  product = {
    name: '',
    description: '',
    available: false
  };
  submitted = false;

  constructor(private productService: ProductService) { }

  ngOnInit(): void {
  }

  createProduct(): void {
    const data = {
      name: this.product.name,
      description: this.product.description
    };

    this.productService.create(data)
      .subscribe(
        response => {
          console.log(response);
          this.submitted = true;
        },
        error => {
          console.log(error);
        });
  }

  newProduct(): void {
    this.submitted = false;
    this.product = {
      name: '',
      description: '',
      available: false
    };
  }

}

Next, open the src/components/product-create/product-create.component.html file and update it as follows:

<div style="width: 500px; margin: auto;">
  <div class="submit-form">
    <div *ngIf="!submitted">
      <div class="form-group">
        <label for="name">Name</label>
        <input
          type="text"
          class="form-control"
          id="name"
          required
          [(ngModel)]="product.name"
          name="name"
        />
      </div>

      <div class="form-group">
        <label for="description">Description</label>
        <input
          class="form-control"
          id="description"
          required
          [(ngModel)]="product.description"
          name="description"
        />
      </div>

      <button (click)="createProduct()" class="btn btn-success">Create</button>
    </div>

    <div *ngIf="submitted">
      <h3>You successfully created a product!</h3>
      <button class="btn btn-success" (click)="newProduct()">New..</button>
    </div>
  </div>
</div>

Displaying the List of Products Component

Next, let's implement the product list component, which makes use of the following service methods:

  • readAll()
  • deleteAll()
  • searchByName()

Open the src/components/product-list/product-list.component.ts file and update it as follows:

import { Component, OnInit } from '@angular/core';
import { ProductService } from 'src/app/services/product.service';

@Component({
  selector: 'app-product-list',
  templateUrl: './product-list.component.html',
  styleUrls: ['./product-list.component.css']
})
export class ProductListComponent implements OnInit {

  products: any;
  currentProduct = null;
  currentIndex = -1;
  name = '';

  constructor(private productService: ProductService) { }

  ngOnInit(): void {
    this.readProducts();
  }

  readProducts(): void {
    this.productService.readAll()
      .subscribe(
        products => {
          this.products = products;
          console.log(products);
        },
        error => {
          console.log(error);
        });
  }

  refresh(): void {
    this.readProducts();
    this.currentProduct = null;
    this.currentIndex = -1;
  }

  setCurrentProduct(product, index): void {
    this.currentProduct = product;
    this.currentIndex = index;
  }

  deleteAllProducts(): void {
    this.productService.deleteAll()
      .subscribe(
        response => {
          console.log(response);
          this.readProducts();
        },
        error => {
          console.log(error);
        });
  }

  searchByName(): void {
    this.productService.searchByName(this.name)
      .subscribe(
        products => {
          this.products = products;
          console.log(products);
        },
        error => {
          console.log(error);
        });
  }
}

Open the src/components/product-list/product-list.component.html file and update it as follows:

<div class="list row">
  <div class="col-md-8">
    <div class="input-group mb-4">
      <input
        type="text"
        class="form-control"
        placeholder="Search by name"
        [(ngModel)]="name"
      />
      <div class="input-group-append">
        <button
          class="btn btn-outline-secondary"
          type="button"
          (click)="searchByName()"
        >
          Search
        </button>
      </div>
    </div>
  </div>
  <div class="col-md-6">
    <h4>Product List</h4>
    <ul class="list-group">
      <li
        class="list-group-item"
        *ngFor="let product of products; let i = index"
        [class.active]="i == currentIndex"
        (click)="setCurrentProduct(product, i)"
      >

      </li>
    </ul>

    <button class="m-4 btn btn-sm btn-danger" (click)="deleteAllProducts()">
      Delete All
    </button>
  </div>
  <div class="col-md-6">
    <div *ngIf="currentProduct">
      <h4>Product</h4>
      <div>
        <label><strong>Name:</strong></label> 
      </div>
      <div>
        <label><strong>Description:</strong></label>

      </div>
      <div>
        <label><strong>Status:</strong></label>

      </div>

      <a class="badge badge-warning" routerLink="/products/">
        Edit
      </a>
    </div>

    <div *ngIf="!currentProduct">
      <br />
      <p>Please click on a product</p>
    </div>
  </div>
</div>

If you click on Edit button of any product, you will be directed to the product details page with the /products/:id URL.

The Product Details Component

Next, let's implement the product details component of our Angular 11 CRUD application.

Open the src/components/product-details/product-details.component.ts file and update it as follows:

import { Component, OnInit } from '@angular/core';
import { ProductService } from 'src/app/services/product.service';
import { ActivatedRoute, Router } from '@angular/router';

@Component({
  selector: 'app-product-details',
  templateUrl: './product-details.component.html',
  styleUrls: ['./product-details.component.css']
})
export class ProductDetailsComponent implements OnInit {
  currentproduct = null;
  message = '';

  constructor(
    private productService: ProductService,
    private route: ActivatedRoute,
    private router: Router) { }

  ngOnInit(): void {
    this.message = '';
    this.getProduct(this.route.snapshot.paramMap.get('id'));
  }

  getProduct(id): void {
    this.productService.read(id)
      .subscribe(
        product => {
          this.currentProduct = product;
          console.log(product);
        },
        error => {
          console.log(error);
        });
  }

  setAvailableStatus(status): void {
    const data = {
      name: this.currentProduct.name,
      description: this.currentProduct.description,
      available: status
    };

    this.productService.update(this.currentProduct.id, data)
      .subscribe(
        response => {
          this.currentProduct.available = status;
          console.log(response);
        },
        error => {
          console.log(error);
        });
  }

  updateProduct(): void {
    this.productService.update(this.currentProduct.id, this.currentProduct)
      .subscribe(
        response => {
          console.log(response);
          this.message = 'The product was updated!';
        },
        error => {
          console.log(error);
        });
  }

  deleteProduct(): void {
    this.productService.delete(this.currentProduct.id)
      .subscribe(
        response => {
          console.log(response);
          this.router.navigate(['/products']);
        },
        error => {
          console.log(error);
        });
  }
}

Open the src/components/product-details/product-details.component.html file and update it as follows:

<div style="width: 500px; margin: auto;">
  <div *ngIf="currentProduct" class="edit-form">
    <h4>Product</h4>
    <form>
      <div class="form-group">
        <label for="title">Name</label>
        <input
          type="text"
          class="form-control"
          id="name"
          [(ngModel)]="currentProduct.name"
          name="name"
        />
      </div>
      <div class="form-group">
        <label for="description">Description</label>
        <input
          type="text"
          class="form-control"
          id="description"
          [(ngModel)]="currentProduct.description"
          name="description"
        />
      </div>

      <div class="form-group">
        <label><strong>Status:</strong></label>

      </div>
    </form>

    <button
      class="badge badge-primary mr-2"
      *ngIf="currentProduct.available"
      (click)="setAvailableStatus(false)"
    >
      Set Not Available
    </button>
    <button
      *ngIf="!currentProduct.available"
      class="badge badge-primary mr-2"
      (click)="setAvailableStatus(true)"
    >
      Set Available
    </button>

    <button class="badge badge-danger mr-2" (click)="deleteProduct()">
      Delete
    </button>

    <button
      type="submit"
      class="badge badge-success"
      (click)="updateProduct()"
    >
      Update
    </button>
    <p></p>
  </div>

  <div *ngIf="!currentProduct">
    <br />
    <p>This product is not accessible</p>
  </div>
</div>

Step 8: Serving the Angular 11 CRUD App

Head back to your command-line interface, make sure your are navigated at the root of your project's directory and run the following command to start a live development server in your local machine:

$ cd Angular11CRUDExample
$ ng serve

Go to your web browser and navigate to the http://localhost:4200/ address to start testing your app.

it will help you.

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