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Building an Angular CRUD App with a Go API

Patricia Arquette
Patricia ArquetteOriginal
2024-11-04 21:36:02485browse

Building an Angular CRUD App with a Go API

CRUD operations (Create, Read, Update, Delete) are the backbone of most web applications. In this tutorial, we’ll show you how to build a CRUD app with Angular on the front end and a GoAPI on the back end, resulting in a fully integrated and efficient full-stack solution.

Prerequisites

  • Node.js
  • Go 1.21
  • MySQL

Setup Angular project

Install Angular 18 and create a new project with the following command.

npm install -g @angular/cli@18.0.0
ng new view --minimal --routing --style css --no-standalone --ssr=false

Angular project structure 

└─ src
   ├─ app
   │  ├─ app-routing.module.ts
   │  ├─ app.component.ts
   │  ├─ app.interceptor.ts
   │  ├─ app.module.ts
   │  └─ components
   │     └─ product
   │        ├─ Create.component.ts
   │        ├─ Delete.component.ts
   │        ├─ Detail.component.ts
   │        ├─ Edit.component.ts
   │        ├─ Index.component.ts
   │        └─ Product.service.ts
   ├─ index.html
   ├─ main.ts
   └─ styles.css

*This project structure will display only the files and folders that we plan to create or modify.

Angular Project files

main.ts 

import { enableProdMode } from '@angular/core'
import { platformBrowserDynamic } from '@angular/platform-browser-dynamic'

import { AppModule } from './app/app.module'

platformBrowserDynamic().bootstrapModule(AppModule).catch(e => console.error(e))

This main.ts file initializes an Angular application by bootstrapping the AppModule using the platformBrowserDynamic function. It sets up the application to run in the browser and handles any errors that occur during the bootstrapping process.

app.module.ts 

import { NgModule } from '@angular/core'
import { BrowserModule } from '@angular/platform-browser'
import { FormsModule } from '@angular/forms'
import { HttpClientModule, HTTP_INTERCEPTORS } from '@angular/common/http'
import { AppRoutingModule } from './app-routing.module'
import { AppComponent } from './app.component'
import { AppInterceptor } from './app.interceptor'

import { ProductIndex } from './components/product/Index.component'
import { ProductCreate } from './components/product/Create.component'
import { ProductDetail } from './components/product/Detail.component'
import { ProductEdit } from './components/product/Edit.component'
import { ProductDelete } from './components/product/Delete.component'

@NgModule({
  declarations: [
    AppComponent,
    ProductIndex,
    ProductCreate,
    ProductDetail,
    ProductEdit,
    ProductDelete,
  ],
  imports: [
    BrowserModule,
    AppRoutingModule,
    FormsModule,
    HttpClientModule
  ],
  providers: [
    { provide: HTTP_INTERCEPTORS, useClass: AppInterceptor, multi: true }
  ],
  bootstrap: [AppComponent]
})

export class AppModule { }

The AppModule is the main module of an Angular application. It imports core Angular modules and sets up routing with AppRoutingModule. The module declares various product-related components. It also registers AppInterceptor as an HTTP interceptor. The AppComponent is set as the bootstrap component, making it the entry point of the application.

app.component.ts 

import { Component } from '@angular/core'

@Component({
  selector: 'app-root',
  template: `<router-outlet></router-outlet>`
})

export class AppComponent { }

The app.component.ts file defines the root component, AppComponent, which uses the directive in its template to display routed views. The component is identified by the app-root selector and serves as the entry point for the Angular application.

app.interceptor.ts 

import { Injectable } from '@angular/core';
import { HttpInterceptor } from '@angular/common/http';
import { HttpRequest, HttpErrorResponse } from '@angular/common/http'
import { Observable, throwError } from 'rxjs'
import { HttpHandler } from '@angular/common/http'
import { HttpEvent } from '@angular/common/http'

@Injectable({
  providedIn: 'root'
})

export class AppInterceptor implements HttpInterceptor {

  baseURL = 'http://localhost:8080/api'

  intercept(request: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>> {
    return next.handle(request.clone({
      url: this.baseURL + request.url,
    }))
  }
}

The AppInterceptor class is an Angular HTTP interceptor that appends a configurable baseURL to all outgoing HTTP request URLs before they are sent to the server. This allows the application to centralize and easily manage the base API endpoint.

app-routing.module.ts 

import { NgModule } from '@angular/core'
import { RouterModule, Routes } from '@angular/router'
import { ProductIndex } from './components/product/Index.component'
import { ProductCreate } from './components/product/Create.component'
import { ProductDetail } from './components/product/Detail.component'
import { ProductEdit } from './components/product/Edit.component'
import { ProductDelete } from './components/product/Delete.component'

const routes: Routes = [
  { path: '', redirectTo: 'product', pathMatch: 'full' },
  { path: 'product', component: ProductIndex },
  { path: 'product/create', component: ProductCreate },
  { path: 'product/:id', component: ProductDetail },
  { path: 'product/edit/:id', component: ProductEdit },
  { path: 'product/delete/:id', component: ProductDelete }
]

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

export class AppRoutingModule { }

The AppRoutingModule sets up routing for an Angular application, including product-related paths for listing, creating, viewing, editing, and deleting products. It also includes a route that redirects from the root path "/" to the product listing page "/product".

Create.component.ts 

import { Component } from '@angular/core'
import { ActivatedRoute, Router } from '@angular/router'
import { ProductService } from './Product.service'

@Component({
  selector: 'product-create',
  template: `
    <div class="container">
      <div class="row">
        <div class="col">
          <form ngNativeValidate method="post" (submit)="create()">
            <div class="row">
              <div class="mb-3 col-md-6 col-lg-4">
                <label class="form-label" for="product_name">Name</label>
                <input id="product_name" name="name" class="form-control" [(ngModel)]="product.Name" maxlength="50" />
                <span *ngIf="errors.name" class="text-danger">{{errors.name}}</span>
              </div>
              <div class="mb-3 col-md-6 col-lg-4">
                <label class="form-label" for="product_price">Price</label>
                <input id="product_price" name="price" class="form-control" [(ngModel)]="product.Price" type="number" />
                <span *ngIf="errors.price" class="text-danger">{{errors.price}}</span>
              </div>
              <div class="col-12">
                <a class="btn btn-secondary" routerLink="/product">Cancel</a>
                <button class="btn btn-primary">Submit</button>
              </div>
            </div>
          </form>
        </div>
      </div>
    </div>`
})
export class ProductCreate {

  product?: any = {}
  errors?: any = {}
  constructor(private router: Router, private route: ActivatedRoute, private ProductService: ProductService) { }

  create() {
    this.ProductService.create(this.product).subscribe(() => {
      this.router.navigateByUrl('/product')
    }, (e) => {
      alert(e.error)
    })
  }
}

The ProductCreate component provides a form for creating a new product, binding input fields for name and price to a product object. On submission, it calls ProductService to create the product and navigates back to the product list. Validation errors are displayed next to the corresponding fields, and any creation errors trigger an alert.

Delete.component.ts 

npm install -g @angular/cli@18.0.0
ng new view --minimal --routing --style css --no-standalone --ssr=false

The ProductDelete component in Delete.component.ts is an Angular component that handles the deletion of a product. It displays a form with read-only fields showing the product's details (ID, name, and price). When the component initializes, it fetches the product details using the product ID from the route. On form submission, the delete() method calls ProductService to delete the product and then redirects to the product list. If there's an error during deletion, an alert is shown.

Detail.component.ts 

└─ src
   ├─ app
   │  ├─ app-routing.module.ts
   │  ├─ app.component.ts
   │  ├─ app.interceptor.ts
   │  ├─ app.module.ts
   │  └─ components
   │     └─ product
   │        ├─ Create.component.ts
   │        ├─ Delete.component.ts
   │        ├─ Detail.component.ts
   │        ├─ Edit.component.ts
   │        ├─ Index.component.ts
   │        └─ Product.service.ts
   ├─ index.html
   ├─ main.ts
   └─ styles.css

The ProductDetail component displays the details of a specific product. It retrieves the product information based on the ID from the route and shows the product's ID, name, and price in read-only fields. The component provides "Back" and "Edit" buttons for navigation. The product details are fetched and displayed when the component initializes.

Edit.component.ts 

import { enableProdMode } from '@angular/core'
import { platformBrowserDynamic } from '@angular/platform-browser-dynamic'

import { AppModule } from './app/app.module'

platformBrowserDynamic().bootstrapModule(AppModule).catch(e => console.error(e))

The ProductEdit component allows users to edit an existing product. It retrieves the product details using the product ID from the route and displays them in a form with editable fields for name and price. On form submission, it updates the product via ProductService and navigates back to the product list. Any errors during fetching or updating are shown as alerts, and validation errors are displayed next to the relevant fields.

Index.component.ts 

import { NgModule } from '@angular/core'
import { BrowserModule } from '@angular/platform-browser'
import { FormsModule } from '@angular/forms'
import { HttpClientModule, HTTP_INTERCEPTORS } from '@angular/common/http'
import { AppRoutingModule } from './app-routing.module'
import { AppComponent } from './app.component'
import { AppInterceptor } from './app.interceptor'

import { ProductIndex } from './components/product/Index.component'
import { ProductCreate } from './components/product/Create.component'
import { ProductDetail } from './components/product/Detail.component'
import { ProductEdit } from './components/product/Edit.component'
import { ProductDelete } from './components/product/Delete.component'

@NgModule({
  declarations: [
    AppComponent,
    ProductIndex,
    ProductCreate,
    ProductDetail,
    ProductEdit,
    ProductDelete,
  ],
  imports: [
    BrowserModule,
    AppRoutingModule,
    FormsModule,
    HttpClientModule
  ],
  providers: [
    { provide: HTTP_INTERCEPTORS, useClass: AppInterceptor, multi: true }
  ],
  bootstrap: [AppComponent]
})

export class AppModule { }

The ProductIndex component displays a list of products in a table format. It fetches the list of products from ProductService on initialization and shows each product's ID, name, and price, with action buttons for viewing, editing, and deleting each product. It also includes a button to navigate to the product creation page.

Product.service.ts 

import { Component } from '@angular/core'

@Component({
  selector: 'app-root',
  template: `<router-outlet></router-outlet>`
})

export class AppComponent { }

The ProductService uses Angular's HttpClient to perform the relevant HTTP requests for product management. It provides methods to:

  • get(id?): Fetch product details by ID or a list of products if no ID is provided.
  • create(data?): Create a new product if data is provided, otherwise fetch the create product page.
  • edit(id, data?): Update a product by ID if data is provided, otherwise fetch product details for editing.
  • delete(id, data?): Delete a product by ID if data is provided, otherwise fetch product details for confirmation.

styles.css 

import { Injectable } from '@angular/core';
import { HttpInterceptor } from '@angular/common/http';
import { HttpRequest, HttpErrorResponse } from '@angular/common/http'
import { Observable, throwError } from 'rxjs'
import { HttpHandler } from '@angular/common/http'
import { HttpEvent } from '@angular/common/http'

@Injectable({
  providedIn: 'root'
})

export class AppInterceptor implements HttpInterceptor {

  baseURL = 'http://localhost:8080/api'

  intercept(request: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>> {
    return next.handle(request.clone({
      url: this.baseURL + request.url,
    }))
  }
}

The CSS adjusts the layout by adding space above the container and spacing out buttons horizontally.

index.html 

import { NgModule } from '@angular/core'
import { RouterModule, Routes } from '@angular/router'
import { ProductIndex } from './components/product/Index.component'
import { ProductCreate } from './components/product/Create.component'
import { ProductDetail } from './components/product/Detail.component'
import { ProductEdit } from './components/product/Edit.component'
import { ProductDelete } from './components/product/Delete.component'

const routes: Routes = [
  { path: '', redirectTo: 'product', pathMatch: 'full' },
  { path: 'product', component: ProductIndex },
  { path: 'product/create', component: ProductCreate },
  { path: 'product/:id', component: ProductDetail },
  { path: 'product/edit/:id', component: ProductEdit },
  { path: 'product/delete/:id', component: ProductDelete }
]

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

export class AppRoutingModule { }

The HTML serves as the main entry point for an Angular application, including Bootstrap for styling, Font Awesome for icons, and as the placeholder for the Angular app.

Setup Go API project 

npm install -g @angular/cli@18.0.0
ng new view --minimal --routing --style css --no-standalone --ssr=false

Create a testing database named "example" and execute the database.sql file to import the table and data.

Go API Project structure 

└─ src
   ├─ app
   │  ├─ app-routing.module.ts
   │  ├─ app.component.ts
   │  ├─ app.interceptor.ts
   │  ├─ app.module.ts
   │  └─ components
   │     └─ product
   │        ├─ Create.component.ts
   │        ├─ Delete.component.ts
   │        ├─ Detail.component.ts
   │        ├─ Edit.component.ts
   │        ├─ Index.component.ts
   │        └─ Product.service.ts
   ├─ index.html
   ├─ main.ts
   └─ styles.css

Go API Project files

.env 

import { enableProdMode } from '@angular/core'
import { platformBrowserDynamic } from '@angular/platform-browser-dynamic'

import { AppModule } from './app/app.module'

platformBrowserDynamic().bootstrapModule(AppModule).catch(e => console.error(e))

This file holds the configuration details for connecting to the database.

db.go 

import { NgModule } from '@angular/core'
import { BrowserModule } from '@angular/platform-browser'
import { FormsModule } from '@angular/forms'
import { HttpClientModule, HTTP_INTERCEPTORS } from '@angular/common/http'
import { AppRoutingModule } from './app-routing.module'
import { AppComponent } from './app.component'
import { AppInterceptor } from './app.interceptor'

import { ProductIndex } from './components/product/Index.component'
import { ProductCreate } from './components/product/Create.component'
import { ProductDetail } from './components/product/Detail.component'
import { ProductEdit } from './components/product/Edit.component'
import { ProductDelete } from './components/product/Delete.component'

@NgModule({
  declarations: [
    AppComponent,
    ProductIndex,
    ProductCreate,
    ProductDetail,
    ProductEdit,
    ProductDelete,
  ],
  imports: [
    BrowserModule,
    AppRoutingModule,
    FormsModule,
    HttpClientModule
  ],
  providers: [
    { provide: HTTP_INTERCEPTORS, useClass: AppInterceptor, multi: true }
  ],
  bootstrap: [AppComponent]
})

export class AppModule { }

This db.go file configures the database connection with GORM. The SetupDatabase function loads environment variables, constructs a MySQL connection string, and initializes a GORM instance, which is stored in the global DB variable.

router.go 

import { Component } from '@angular/core'

@Component({
  selector: 'app-root',
  template: `<router-outlet></router-outlet>`
})

export class AppComponent { }

This router.go file sets up routing for a Go application using the Gin framework. The SetupRouter function initializes a Gin router with CORS middleware to allow all origins. It defines routes for handling product-related operations under the /api/products path, each mapped to a method in the ProductController. Finally, it starts the Gin server.

product.go 

import { Injectable } from '@angular/core';
import { HttpInterceptor } from '@angular/common/http';
import { HttpRequest, HttpErrorResponse } from '@angular/common/http'
import { Observable, throwError } from 'rxjs'
import { HttpHandler } from '@angular/common/http'
import { HttpEvent } from '@angular/common/http'

@Injectable({
  providedIn: 'root'
})

export class AppInterceptor implements HttpInterceptor {

  baseURL = 'http://localhost:8080/api'

  intercept(request: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>> {
    return next.handle(request.clone({
      url: this.baseURL + request.url,
    }))
  }
}

This product.go file defines a Product model for use with GORM. It specifies a Product struct with three fields: Id (an auto-incrementing primary key), Name, Price.

product_controller.go 

import { NgModule } from '@angular/core'
import { RouterModule, Routes } from '@angular/router'
import { ProductIndex } from './components/product/Index.component'
import { ProductCreate } from './components/product/Create.component'
import { ProductDetail } from './components/product/Detail.component'
import { ProductEdit } from './components/product/Edit.component'
import { ProductDelete } from './components/product/Delete.component'

const routes: Routes = [
  { path: '', redirectTo: 'product', pathMatch: 'full' },
  { path: 'product', component: ProductIndex },
  { path: 'product/create', component: ProductCreate },
  { path: 'product/:id', component: ProductDetail },
  { path: 'product/edit/:id', component: ProductEdit },
  { path: 'product/delete/:id', component: ProductDelete }
]

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

export class AppRoutingModule { }

The product_controller.go file defines a ProductController struct with methods to handle CRUD operations for products in a Go application using the Gin framework.

  • Index Retrieves and returns a list of all products.
  • Get Fetches and returns a single product by its ID.
  • Create Creates a new product from the request body.
  • Update Updates an existing product with the data from the request body.
  • Delete Deletes a product by its ID.

main.go 

import { Component } from '@angular/core'
import { ActivatedRoute, Router } from '@angular/router'
import { ProductService } from './Product.service'

@Component({
  selector: 'product-create',
  template: `
    <div class="container">
      <div class="row">
        <div class="col">
          <form ngNativeValidate method="post" (submit)="create()">
            <div class="row">
              <div class="mb-3 col-md-6 col-lg-4">
                <label class="form-label" for="product_name">Name</label>
                <input id="product_name" name="name" class="form-control" [(ngModel)]="product.Name" maxlength="50" />
                <span *ngIf="errors.name" class="text-danger">{{errors.name}}</span>
              </div>
              <div class="mb-3 col-md-6 col-lg-4">
                <label class="form-label" for="product_price">Price</label>
                <input id="product_price" name="price" class="form-control" [(ngModel)]="product.Price" type="number" />
                <span *ngIf="errors.price" class="text-danger">{{errors.price}}</span>
              </div>
              <div class="col-12">
                <a class="btn btn-secondary" routerLink="/product">Cancel</a>
                <button class="btn btn-primary">Submit</button>
              </div>
            </div>
          </form>
        </div>
      </div>
    </div>`
})
export class ProductCreate {

  product?: any = {}
  errors?: any = {}
  constructor(private router: Router, private route: ActivatedRoute, private ProductService: ProductService) { }

  create() {
    this.ProductService.create(this.product).subscribe(() => {
      this.router.navigateByUrl('/product')
    }, (e) => {
      alert(e.error)
    })
  }
}

This main.go file is the entry point for the Go application. It imports configuration and routing packages, then calls config.SetupDatabase()to initialize the database connection and router.SetupRouter() to set up the application’s routes.

Run projects

Run Angular project

import { Component } from '@angular/core'
import { ActivatedRoute, Router } from '@angular/router'
import { ProductService } from './Product.service'

@Component({
  selector: 'product-delete',
  template: `
    <div class="container">
      <div class="row">
        <div class="col">
          <form ngNativeValidate method="post" (submit)="this.delete()">
            <div class="row">
              <div class="mb-3 col-md-6 col-lg-4">
                <label class="form-label" for="product_id">Id</label>
                <input readonly id="product_id" name="id" class="form-control" value="{{product.Id}}" type="number" required />
              </div>
              <div class="mb-3 col-md-6 col-lg-4">
                <label class="form-label" for="product_name">Name</label>
                <input readonly id="product_name" name="name" class="form-control" value="{{product.Name}}" maxlength="50" />
              </div>
              <div class="mb-3 col-md-6 col-lg-4">
                <label class="form-label" for="product_price">Price</label>
                <input readonly id="product_price" name="price" class="form-control" value="{{product.Price}}" type="number" />
              </div>
              <div class="col-12">
                <a class="btn btn-secondary" routerLink="/product">Cancel</a>
                <button class="btn btn-danger">Delete</button>
              </div>
            </div>
          </form>
        </div>
      </div>
    </div>`
})
export class ProductDelete {

  product?: any = {}
  constructor(private router: Router, private route: ActivatedRoute, private ProductService: ProductService) { }

  ngOnInit() {
    this.get()
  }

  get() {
    return this.ProductService.delete(this.route.snapshot.params['id']).subscribe(data => {
      this.product = data
    }, e => {
      alert(e.error)
    })
  }

  delete() {
    this.ProductService.delete(this.route.snapshot.params['id'], this.product).subscribe(() => {
      this.router.navigateByUrl('/product')
    }, (e) => {
      alert(e.error)
    })
  }
}

Run Go API project

import { Component } from '@angular/core'
import { ActivatedRoute } from '@angular/router'
import { ProductService } from './Product.service'

@Component({
  selector: 'product-detail',
  template: `
    <div class="container">
      <div class="row">
        <div class="col">
          <form ngNativeValidate method="post">
            <div class="row">
              <div class="mb-3 col-md-6 col-lg-4">
                <label class="form-label" for="product_id">Id</label>
                <input readonly id="product_id" name="id" class="form-control" value="{{product.Id}}" type="number" required />
              </div>
              <div class="mb-3 col-md-6 col-lg-4">
                <label class="form-label" for="product_name">Name</label>
                <input readonly id="product_name" name="name" class="form-control" value="{{product.Name}}" maxlength="50" />
              </div>
              <div class="mb-3 col-md-6 col-lg-4">
                <label class="form-label" for="product_price">Price</label>
                <input readonly id="product_price" name="price" class="form-control" value="{{product.Price}}" type="number" />
              </div>
              <div class="col-12">
                <a class="btn btn-secondary" routerLink="/product">Back</a>
                <a class="btn btn-primary" routerLink="/product/edit/{{product.Id}}">Edit</a>
              </div>
            </div>
          </form>
        </div>
      </div>
    </div>`
})
export class ProductDetail {

  product?: any = {}
  constructor(private route: ActivatedRoute, private ProductService: ProductService) { }

  ngOnInit() {
    this.get()
  }

  get() {
    return this.ProductService.get(this.route.snapshot.params['id']).subscribe(data => {
      this.product = data
    }, e => {
      alert(e.error)
    })
  }
}

Open the web browser and goto http://localhost:4200

You will find this product list page.

Building an Angular CRUD App with a Go API

Testing

Click the "View" button to see the product details page.

Building an Angular CRUD App with a Go API

Click the "Edit" button to modify the product and update its details.

Building an Angular CRUD App with a Go API

Click the "Submit" button to save the updated product details.

Building an Angular CRUD App with a Go API

Click the "Create" button to add a new product and input its details.

Building an Angular CRUD App with a Go API

Click the "Submit" button to save the new product.

Building an Angular CRUD App with a Go API

Click the "Delete" button to remove the previously created product.

Building an Angular CRUD App with a Go API

Click the "Delete" button to confirm the removal of this product.

Building an Angular CRUD App with a Go API

Conclusion

In conclusion, we have learned how to create a basic Angular project with components, views, and routing, while setting up an API using the Gin framework as the backend. By utilizing GORM for database operations, we've successfully built a dynamic front-end that seamlessly integrates with a powerful and efficient backend. This combination forms a solid foundation for developing modern, full-stack web applications.

Source code: https://github.com/stackpuz/Example-CRUD-Angular-18-Go

Create an Angular CRUD App in Minutes: https://stackpuz.com

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