Angular 4.3 introduced a new service called HttpClient. The HttpClient Service was the replacement for the Http service from Angular
2. The HttpClient works mostly the same as the old HTTP service. The HttpClient
service is handling both single and concurrent data. Http service still works but it will be removed in a future release.
The types of HttpClient service -
1. HttpClient.get
2. HttpClient.post
3. HttpClient.put
4. HttpClient.delete
In the below example, I will share how to create Angular
5 REST API using Angular HttpClient services and other - Installing HttpClientModule - app.module.ts
import { BrowserModule } from '@angular/platform-browser';
import { NgModule } from '@angular/core';
import {FormsModule, FormGroup} from '@angular/forms';
import {RouterModule} from '@angular/router';
import {HttpClientModule} from "@angular/common/http";
//MY COMPONENTS
import { AppComponent } from './app.component';
import { LoginComponent } from './login/login.component';
import { RegisterComponent } from './register/register.component';
import { EmployeeComponent } from './employee/employee.component';
//My Services
import { AuthServiceService } from './auth-service.service';
import { AuthGuard } from './auth.guard';
import {EmployeeService} from '../app/employee.service';
@NgModule({
declarations: [
AppComponent,
LoginComponent,
RegisterComponent,
EmployeeComponent
],
imports: [
BrowserModule,
FormsModule,
HttpClientModule,
RouterModule.forRoot([
{ path: '', component: AppComponent, pathMatch: 'full' },
{ path: 'register', component: RegisterComponent },
{ path: 'employee', component: EmployeeComponent},
{ path: 'login', component: LoginComponent}])
],
providers: [EmployeeService],
bootstrap: [AppComponent]
})
export class AppModule { }
Injecting HttpClient – employee.service.ts
import { Injectable } from '@angular/core';
import {HttpClient, HttpParams, HttpHeaders} from "@angular/common/http";
import { Employee } from './employee';
import{ AppConstants} from '../app/constants'
import { constants } from 'fs';
@Injectable()
export class EmployeeService {
//variable initialization
headers : any;
_baseURL : string;
//constructor initialization
constructor(private _htc:HttpClient) {
this.headers = new HttpHeaders().set('content-type', 'application/json');
this._baseURL = AppConstants.baseURL;
}
// POST employee - for creating a New
employee.
addEmployee(emp :any){
var employee = {
name:emp.name,
Dep:emp.Dep,
Des:emp.Des
}
return this._htc.post<Employee>(this._baseURL+'/Employees/Add', employee, (this.headers));
}
//PUT employee - for update employee.
editEmployee(emp :any){
var employee = {
id:emp.id,
name:emp.name,
Dep:emp.Dep,
Des:emp.Des
}
return this._htc.put<Employee>(this._baseURL+'/Employees/Edit', employee, (this.headers));
}
//DELETE employee - for delete
employee.
deleteEmployee(id :string){
return this._htc.delete<Employee>(this._baseURL+'/Employees/Delete/'+id);
}
}
Use of Constants - constants.ts
export class AppConstants {
public static get baseURL(): string { return "http://localhost:4200/api"; }
}
Use of Services in Components – employee.component.ts
import { Component, OnInit } from '@angular/core';
import {Employee } from '../employee'
import { Validators, FormGroup, FormControl } from '@angular/forms';
import {EmployeeService} from '../employee.service'
import { constants } from 'fs';
@Component({
selector: 'app-employee',
templateUrl: './employee.component.html',
styleUrls: ['./employee.component.css']
})
export class EmployeeComponent implements OnInit {
constructor( public _empService: EmployeeService) { }
empForm:any;
ngOnInit() {
this.empForm = new FormGroup({
'name': new FormControl(this.employee.name, [Validators.required,Validators.minLength(4)]),
'Dep': new FormControl(this.employee.Dep, [Validators.required, Validators.minLength(10)]),
'Desc': new FormControl(this.employee.Desc, Validators.required)
});
}
employee = new Employee(0,'','','');
submitted = false;
//Add new Employee
onSubmit() {
this.submitted = true;
let isSuccess = this._empService.addEmployee(this.employee);
if(isSuccess){
//handle success
console.log(isSuccess);
}else{
//handle errors
}
}
}
UI part - employee.component.html
<div
class="container">
<h1>Employee
Form</h1>
<form
#empForm="ngForm"
(ngSubmit)="onSubmit()">
<div
class="form-group">
<label
for="name">Name</label>
<input
type="text"
class="form-control"
id="name" required
[(ngModel)]="employee.name"
name="name">
</div>
<div
class="form-group">
<label
for="Dep">Department</label>
<input
type="text"
class="form-control"
id="Dep" required
[(ngModel)]="employee.Dep"
name="Dep">
</div>
<div
class="form-group">
<label
for="Desc">Desc</label>
<input
type="text"
class="form-control"
id="Desc" required
[(ngModel)]="employee.Desc"
name="Desc">
</div>
<button
type="submit"
class="btn
btn-success" [disabled]="!empForm.form.valid">Submit</button>
</form>
</div>
<div
[hidden]="!submitted">
<h2 style="color:green;">Record
Added Scussfully!</h2>
</div>
Result looks like –
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Anil Singh is an author, tech blogger, and software programmer. Book writing, tech blogging is something do extra and Anil love doing it. For more detail, kindly refer to this link..
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