Lær Angular 6 ved at oprette en full-stack applikation

Vinkel 6 er ude! De nye funktioner inkluderer bedre ydelse, nye kraftfulde CLI-tilføjelser og en ny måde at indsprøjte tjenester på.

Denne vejledning er for begyndere. Du lærer Angular ved eksempel ved at opbygge en CRACK med fuld stak - Opret, læs, opdater og slet - webapplikation. Vi bruger den nyeste version af den mest populære ramme og platform til opbygning af mobile og desktop-applikationer på klientsiden. Navnet på disse applikationer er SPA'er eller applikationer med en enkelt side.

I back-end bruger vi Python med Django. Django er den mest populære pythoniske webramme designet til perfektionister med deadlines.

I en nøddeskal lærer du at generere Angular 6 apps, generere komponenter og tjenester og tilføje routing. Du lærer også at bruge forskellige funktioner såsom HttpClient til at sende AJAX-anmodninger og HTTP-opkald og abonnere på RxJS 6 observerbare og så videre.

Ved afslutningen af ​​denne Angular 6- selvstudie lærer du ved at opbygge en eksempelapplikation fra den virkelige verden:

  • hvordan man installerer den nyeste version af Angular CLI,
  • hvordan man bruger Angular 6 CLI til at generere et nyt Angular 6- projekt,
  • hvordan man bruger Angular 6 til at opbygge en simpel CRM-applikation,
  • hvad er en komponent og komponentbaseret arkitektur
  • hvordan man bruger RxJS 6 Observables og operatorer ( map()og filter()osv.)
  • hvordan man opretter Angular 6-komponenter,
  • hvordan man tilføjer komponent routing og navigation,
  • hvordan man bruger HttpClient til at forbruge en REST API osv.

Django-eksemplet CRUD Back-End

Vi bruger en simpel CRUD API bygget med Django og Django REST ramme. Da dette er en Angular tutorial, fokuserer vi ikke på at opbygge API. Dette vil være genstand for en separat vejledning. Du kan hente kildekoden til back-end API'en fra dette lager.

Du kan bruge følgende kommandoer til at starte udviklingsserveren:

# Clone the project and navigate into it $ git clone //github.com/techiediaries/django-crm $ cd django-crm # Create a virtual environment and install packages $ pipenv install # Activate the virtual environment $ pipenv shell # Create and migrate the database then run the local development server $ python manage.py migrate $ python manage.py runserver

Din server kører fra //localhost:8000.

Vi bruger pipenv, det officielt anbefalede pakkehåndteringsværktøj til Python. Du bliver nødt til at have det installeret. Processen er ret enkel afhængigt af dit operativsystem.

Vinkel 6 CRUD Eksempel

Eksemplet Angular 6-applikation, som vi skal bygge, er front-end for en CRM RESTful API. Det giver dig mulighed for at oprette konti, kundeemner, muligheder og kontakter. Det er et perfekt eksempel på en CRUD-applikation (Opret, læs, opdater og slet), der er bygget som en SPA (Single Page Application).

Eksemplet på applikationen er i gang, så vi bygger det gennem en række tutorials. Den opdateres til at indeholde avancerede funktioner såsom RxJS 6 og JWT-godkendelse. Vi bruger også Bootstrap 4 og Angular 6 Material til bygning og styling af UI-komponenterne. Du har enten brug for Bootstrap 4 eller Angular Material til styling. Afhængigt af dit valg kan du følge separate vejledninger:

  • Opbygning af brugergrænsefladen med kantet 6-materiale
  • Opbygning af brugergrænsefladen med Bootstrap 4

Installation af Angular CLI (v6.0.0)

Sørg for, at du har Node.js installeret, og kør derefter følgende kommando i din terminal for at installere Angular CLI v 6.0.0 .

npm -g install @angular/cli

Du kan kontrollere den installerede version ved at køre følgende kommando:

Nu er du klar til at oprette et projekt ved hjælp af Angular CLI v6. Kør blot følgende kommando i din terminal:

CLI genererer automatisk en masse filer, der er fælles for de fleste Angular 6-projekter. Det installerer også de nødvendige afhængigheder til dit projekt.

Vi arbejder for det meste inde i src/appmappen. Dette er projektets katalogstruktur:

Du kan betjene din applikation lokalt ved at køre følgende kommandoer:

# Navigate inside your project's folder $ cd crmapp # Serve your application $ ng serve

Din ansøgning kører fra //localhost:4200.

Dette er et skærmbillede af applikationens startside:

Komponenter i vinkel 6 | 5 | 4

Hvad er en komponent nu?

En komponent er en TypeScript-klasse. Den har en HTML-skabelon og et valgfrit sæt CSS-stilarter, der styrer en del af skærmen.

Komponenter er det vigtigste koncept i Angular 6. En Angular 6-applikation er grundlæggende et komponentetræ med en rodkomponent (den berømte AppComponent ). Rodkomponenten er den, der findes i bootstrap-arrayet i NgModulehovedmodulet app.module.ts.

Et vigtigt aspekt af komponenterne er genanvendelighed. En komponent kan genbruges i hele applikationen og endda i andre applikationer. Almindelig og gentagelig kode, der udfører en bestemt opgave, kan indkapsles i en genanvendelig komponent. Denne komponent kan kaldes, når vi har brug for den funktionalitet, den giver.

Hver bootstrapped komponent er basen for sit eget træ af komponenter. Indsættelse af en bootstrapped komponent udløser normalt en kaskade af komponentskabelser, der udfylder det træ. Kilde

Komponentbaseret arkitektur

En kantet applikation er lavet af flere komponenter. Disse komponenter danner en træstruktur med forældre- og underordnede komponenter.

En komponent er en uafhængig blok af et stort system (webapplikation). Det kommunikerer med de andre byggesten (komponenter) i systemet ved hjælp af input og output. En komponent har tilknyttet visning, data og adfærd. Det kan have forældre- og underordnede komponenter.

Komponenter muliggør maksimal genanvendelighed, let test, vedligeholdelse og adskillelse af bekymringer.

Lad os nu se dette praktisk. Gå over til din Angular-applikationsprojektmappe, og åbn src/appmappen. Du finder følgende filer:

  • app.component.css: the CSS file for the component
  • app.component.html: the HTML view for the component
  • app.component.spec.ts: the unit tests or spec file for the component
  • app.component.ts: the component code (data and behavior)
  • app.module.ts: the application main module

Except for the last file which contains the declaration of the application main (root) Module, all these files are used to create a component. It’s the AppComponent: The root component of our application. All other components we are going to create next will be direct or un-direct children of the root component.

Demystifying the AppComponent (The Root Component of Angular Applications)

Go ahead and open the src/app/app.component.ts file and let's understand the code behind the main/root component of the application.

First, this is the code:

import { Component } from '@angular/core';@Component({ selector: 'app-root', templateUrl: './app.component.html', styleUrls: ['./app.component.css']})export class AppComponent { title = 'app';}

We first import the Component decorator from @angular/core. Then we use it to decorate the TypeScript class AppComponent. The Component decorator takes an object with many parameters such as:

  • selector: specifies the tag that can be used to call this component in HTML templates just like the standard HTML tags
  • templateUrl: indicates the path of the HTML template that will be used to display this component (you can also use the template parameter to include the template inline as a string)
  • styleUrls: specifies an array of URLs for CSS style-sheets for the component

The export keyword is used to export the component so that it can be imported from other components and modules in the application.

The title variable is a member variable that holds the string ‘app’. There is nothing special about this variable and it’s not a part of the canonical definition of an Angular component.

Now let’s see the corresponding template for this component. If you open src/app/app.component.html this is what you'll find:

Welcome to !

Angular Logo

Here are some links to help you start:

  • Tour of Heroes

  • CLI Documentation

  • Angular blog

The template is a normal HTML file (almost all HTML tags are valid to be used inside Angular templates except for some tags such as pt >, tml> ; and ) with the exception that it can contain template variables (in this case the title variable) or expressions ({ {...}}) that can be used to insert values in the DOM dynamically. This is called interpolation or data binding. You can find more information about templates from the docs.

You can also use other components directly inside Angular templates (via the selector property) just like normal HTML.

If you are familiar with the MVC (Model View Controller) pattern, the component class plays the role of the Controller. The HTML template plays the role of the View.

Angular 6 Components by Example

After getting the theory behind Angular components, let’s now create the components for our simple CRM application.

Our REST API, built with Django, exposes these endpoints:

  • /api/accounts: create or read a paginated list of accounts
  • /api/accounts/<id>: read, update or delete an account
  • /api/contacts: create or read a paginated list of contacts
  • /api/contacts/<id>: read, update or delete a contact
  • /api/leads: create or read a paginated list of leads
  • /api/leads/<id>: read, update or delete a lead
  • /api/opportunities: create or read a paginated list of opportunities
  • /api/opportunities/<id>: read, update or delete an opportunity

Before adding routing to our application we first need to create the application’s components. Based on the exposed REST API architecture we can divide our application into these components:

  • AccountListComponent: this component displays and controls a tabular list of accounts
  • AccountCreateComponent: this component displays and controls a form for creating or updating accounts
  • ContactListComponent: displays a table of contacts
  • ContactCreateComponent: displays a form to create or update a contact
  • LeadListComponent: displays a table of leads
  • LeadCreateComponent: displays a form to create or update a lead
  • OpportunityListComponent: displays a table of opportunities
  • OpportunityCreateComponent: displays a form to create or update an opportunity

Let’s use the Angular CLI to create the components

ng generate component AccountList ng generate component AccountCreate ng generate component ContactList ng generate component ContactCreate ng generate component LeadList ng generate component LeadCreate ng generate component OpportunityList ng generate component OpportunityCreate

This is the output of the first command:

CREATE src/app/account-list/account-list.component.css (0 bytes) CREATE src/app/account-list/account-list.component.html (31 bytes) CREATE src/app/account-list/account-list.component.spec.ts (664 bytes) CREATE src/app/account-list/account-list.component.ts (292 bytes) UPDATE src/app/app.module.ts (418 bytes)

You can see that the command generates all the files to define a component and also updates src/app/app.module.ts.

If you open src/app/app.module.ts after running all commands, you can see that all components are automatically added to the AppModuledeclarations array.:

import { BrowserModule } from '@angular/platform-browser';import { NgModule } from '@angular/core';import { AppComponent } from './app.component';import { AccountListComponent } from './account-list/account-list.component';import { AccountCreateComponent } from './account-create/account-create.component';import { ContactListComponent } from './contact-list/contact-list.component';import { ContactCreateComponent } from './contact-create/contact-create.component';import { LeadListComponent } from './lead-list/lead-list.component';import { LeadCreateComponent } from './lead-create/lead-create.component';import { OpportunityListComponent } from './opportunity-list/opportunity-list.component';import { OpportunityCreateComponent } from './opportunity-create/opportunity-create.component';@NgModule({declarations: [ AppComponent, AccountListComponent, AccountCreateComponent, ContactListComponent, ContactCreateComponent, LeadListComponent, LeadCreateComponent, OpportunityListComponent, OpportunityCreateComponent],imports: [ BrowserModule],providers: [],bootstrap: [AppComponent]})export class AppModule { }

If you are creating components manually, you need to make sure to include them manually so they can be recognized as part of the module.

Adding Angular 6 Routing

Angular CLI provides the --routing switch (ng new crmapp --routing) that enables you to add routing automatically. We’re going to add routing manually. I want you to understand the various pieces involved in adding component routing to your Angular application.

In fact, adding routing is quite simple:

  • add a separate module (which can be called AppRoutingModule) in a file app-routing.module.ts, and import the module by including it in the imports of main AppModule,
  • add r-outlet> in app.component.html (this is where the Angular Router will insert components matching the current path),
  • add routes (each route is an object with properties such as path and component etc.).

This is the initial content of app-routing.module.ts:

import { NgModule } from '@angular/core';import { Routes, RouterModule } from '@angular/router';const routes: Routes = [];@NgModule({ imports: [RouterModule.forRoot(routes)], exports: [RouterModule]})export class AppRoutingModule { }

The routes will contain all the routes of the application. After creating the components we’ll see how to add routes to this array.

For now, we want to redirect the visitor to the /accounts path when the home URL is visited so the first path we'll add is:

{ path: '', redirectTo: 'accounts', pathMatch: 'full' },

The pathMatch specifies the matching strategy. full means that we want to fully match the path.

Next, let’s add the other paths:

{ path: '', redirectTo: 'accounts', pathMatch: 'full' },{ path: 'accounts', component: AccountListComponent},{ path: 'create-account', component: AccountCreateComponent},{ path: 'contacts', component: ContactListComponent},{ path: 'create-contact', component: ContactCreateComponent},{ path: 'leads', component: LeadListComponent},{ path: 'create-lead', component: LeadCreateComponent},{ path: 'opportunities', component: OpportunityListComponent},{ path: 'create-opportunity', component: OpportunityCreateComponent}];

Now open src/app/app.module.ts and import the routing module then add it to the imports array:

import {AppRoutingModule} from './app-routing.module';[...]@NgModule({declarations: [AppComponent,[...]],imports: [ BrowserModule, AppRoutingModule],[...]})export class AppModule { }

Finally, open src/app/app.component.html then add the navigation links and the router outlet:

 Accounts Create Account Contacts Create Contact Leads Create Lead Opportunities Create Opportunity 

An Example for Consuming the REST API Using Angular 6 HttpClient

Now we’ve created the different components and added routing and navigation. Let’s see an example of how to use the HttpClient of Angular 6 to consume the RESTful API back-end.

First, you need to add the HttpClientModule module to the imports array of the main application module:

[..]import { HttpClientModule } from '@angular/common/http';@NgModule({declarations: [..],imports: [[..]HttpClientModule],providers: [],bootstrap: [AppComponent]})export class AppModule { }

Create an Angular 6 Service/Provider

A service is a global class that can be injected into any component. It’s used to encapsulate code that can be common between multiple components in one place instead of repeating it throughout various components.

Now, let's create a service that encapsulates all the code needed for interacting with the REST API. Using Angular CLI run the following command:

Two files: src/app/api.service.ts and src/app/api.service.spec.ts will be generated. The first contains code for the service and the second contains tests.

Open src/app/api.service.ts then import and inject the HttpClient class.

import { Injectable } from '@angular/core';import { HttpClient} from '@angular/common/http';@Injectable({providedIn: 'root'})export class APIService { constructor(private httpClient: HttpClient) {}}

Angular 6 provides a way to register services/providers directly in the @Injectable() decorator by using the new providedIn attribute. This attribute accepts any module of your application or 'root' for the main app module. Now you don't have to include your service in the providers array of your module.

Getting Contacts/Sending HTTP GET Request Example

Let’s start with the contacts API endpoint.

  • First, we’ll add a method to consume this endpoint in our global API service,
  • next, we’ll inject the API service and call the method from the corresponding component class (ContactListComponent)
  • and finally, we’ll display the result (the list of contacts) in the component template.

Open src/app/api.service.ts and add the following method:

export class APIService {API_URL = '//localhost:8000';constructor(private httpClient: HttpClient) {}getContacts(){ return this.httpClient.get(`${this.API_URL}/contacts`);}

Next, open src/app/contact-list/contact-list.component.ts and inject the APIService then call the getContacts() method:

import { Component, OnInit } from '@angular/core';import { APIService } from '../api.service';@Component({ selector: 'app-contact-list', templateUrl: './contact-list.component.html', styleUrls: ['./contact-list.component.css']})export class ContactListComponent implements OnInit {private contacts: Array = [];constructor(private apiService: APIService) { }ngOnInit() { this.getContacts();}public getContacts(){ this.apiService.getContacts().subscribe((data: Array) => { this.contacts = data; console.log(data); });}

Now let’s display the contacts in the template. Open src/app/contact-list/contact-list.component.html and add the following code:

My Contacts

First Name Last Name Phone Email Address
{{ contact.first_name }} {{ contact.last_name }} {{ contact.phone }} {{ contact.email }} {{ contact.address }}

This is a screen-shot of the component:

Creating Contacts/Sending HTTP POST Request Example

Now let’s create a method to send HTTP Post request to create a random contact. Open the API service file and add the following method:

createContact(contact){ return this.httpClient.post(`${this.API_URL}/contacts/`,contact);}

Next, let’s call this method from the ContactCreateComponent to create a contact. First, open src/app/contact-create/contact-create.component.ts and add the following code:

import { Component, OnInit } from '@angular/core';import { APIService } from '../api.service';@Component({selector: 'app-contact-create',templateUrl: './contact-create.component.html',styleUrls: ['./contact-create.component.css']})export class ContactCreateComponent implements OnInit {constructor(private apiService: APIService) { }ngOnInit() {}createContact(){var contact = { account: 1, address: "Home N 333 Apartment 300", createdBy: 1, description: "This is the third contact", email: "[email protected]", first_name: "kaya", isActive: true, last_name: "Abbes", phone: "00121212101"};this.apiService.createContact(contact).subscribe((response) => { console.log(response);});};}}

For now, we’re simply hard-coding the contact info for the sake of simplicity.

Next, open src/app/contact-create/contact-create.component.html and add a button to call the method to create a contact:

Create Contact

Create Contact

Conclusion

Throughout this Angular 6 tutorial for beginners, we’ve seen, by building a simple real-world CRUD example, how to use different Angular concepts to create simple full-stack CRUD application with Angular and Django. You can find the source code in this repository.