Django RestApis CRUD Application with Angular 6 & PostgreSQL tutorial

In this tutorial, we show you Angular 6 Http Client & Django Server example that uses Django to do CRUD with PostgreSQL (including finder method) and Angular 6 as front-end technology to make request and receive response.

Related Post: Django RestApis example – GET/POST/PUT/DELETE requests to PostgreSQL database

Technologies

– Django 2.1
– Angular 6
– RxJS 6
– PostgreSQL 9.5

Project Overview

1. Django Server

With this system, we can use Angular Client to work with PostgreSQL Database via Django Server which has APIs:

• GET api/customers/: get all customers
• GET api/customers/[id]: get a customer by id
• GET api/customers/age/[age]: find all customers by age
• POST api/customers/: save a customer
• PUT api/customers/[id]: update a customer by id
• DELETE api/customers/[id]: delete a customer by id
• DELETE api/customers/: delete all customers

2. Angular 6 Client

The image below shows overview about Angular Components that we will create:

Django RestApi server

Project structure

There are several folders and files in our Django project:

– customers/apps.py: declares CustomersConfig class (subclass of the django.apps.AppConfig) that represents our Django app and its configuration.
– gkzRestApi/settings.py: configures settings for the Django project, including INSTALLED_APPS list with Django REST framework and Customers Application.
– customers/models.py: defines Customer data model class (subclass of the django.db.models.Model).
– migrations/0001_initial.py: is generated by makemigrations command, includes the code to create the Customer model, will be run by migrate to generate PostgreSQL database table for Customer model.
– customers/serializers.py: declares CustomerSerializer class (subclass of rest_framework.serializers.ModelSerializer) for Customer instances to manage serialization to JSON and deserialization from JSON.
– customers/views.py: contains methods to process HTTP requests and produce HTTP responses (using CustomerSerializer).
– customers/urls.py: defines urlpatterns to be matched with request functions in the views.py.
– gkzRestApi/urls.py: defines root URL configurations that includes the URL patterns declared in customers/urls.py.

Setup Django RestApi project

Install Django REST framework

Django REST framework works on top of Django and helps us to build RESTful Web Services flexibly. To install this package, run command:
pip install djangorestframework

Create RestApi project

Create Django project named gkzRestApi with command:
django-admin startproject gkzRestApi

Install Python PostgreSQL adapter

We have to install Python PostgreSQL adapter to work with PostgreSQL database.
In this tutorial, we use psycopg2: pip install psycopg2.

Setup PostgreSQL Database engine

Open gkzRestApi/settings.py and change declaration of DATABASES:

DATABASES = {
   'default': {
        'ENGINE': 'django.db.backends.postgresql',
        'NAME': 'testdb',
        'USER': 'postgres',
        'PASSWORD': '123',
        'HOST': '127.0.0.1',
        'PORT': '5432',
    }
}

Create Customers App

Run following commands to create new Django App named customers:
– cd gkzRestApi
– python manage.py startapp customers

Open customers/apps.py, we can see CustomersConfig class (subclass of the django.apps.AppConfig) that represents our Django app and its configuration:

from django.apps import AppConfig


class CustomersConfig(AppConfig):
    name = 'customers'

Add Django Rest framework & RestApi App to Django project

Open gkzRestApi/settings.py, find INSTALLED_APPS, then add:

INSTALLED_APPS = [
    'django.contrib.admin',
    'django.contrib.auth',
    'django.contrib.contenttypes',
    'django.contrib.sessions',
    'django.contrib.messages',
    'django.contrib.staticfiles',
    # Django REST framework 
    'rest_framework',
    # Customers application 
    'customers.apps.CustomersConfig',
]

Add CORS Configurations

Inside gkzRestApi/settings.py, add:

INSTALLED_APPS = [
    ...
    # CORS
    'corsheaders',
]

MIDDLEWARE = [
    'django.middleware.security.SecurityMiddleware',
    'django.contrib.sessions.middleware.SessionMiddleware',
    'django.middleware.common.CommonMiddleware',
    'django.middleware.csrf.CsrfViewMiddleware',
    'django.contrib.auth.middleware.AuthenticationMiddleware',
    'django.contrib.messages.middleware.MessageMiddleware',
    'django.middleware.clickjacking.XFrameOptionsMiddleware',
    # CORS
    'corsheaders.middleware.CorsMiddleware',  
    'django.middleware.common.CommonMiddleware',  
]

CORS_ORIGIN_ALLOW_ALL = False
CORS_ORIGIN_WHITELIST = (
    'localhost:4200',
)

Implement Django RestApi App

Data Model

Create Data Model

customers/models.py

from django.db import models


class Customer(models.Model):
    name = models.CharField(max_length=70, blank=False, default='')
    age = models.IntegerField(blank=False, default=1)
    active = models.BooleanField(default=False)

Run initial migration for data model

Run following Python script:
python manage.py makemigrations customers

We can see output text:

Migrations for 'customers':
  customers\migrations\0001_initial.py
    - Create model Customer

It indicates that the customers/migrations/0001_initial.py file includes code to create Customer data model:

# Generated by Django 2.1.7 on 2019-03-07 01:28

from django.db import migrations, models


class Migration(migrations.Migration):

    initial = True

    dependencies = [
    ]

    operations = [
        migrations.CreateModel(
            name='Customer',
            fields=[
                ('id', models.AutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
                ('name', models.CharField(default='', max_length=70)),
                ('age', models.IntegerField(default=1)),
                ('active', models.BooleanField(default=False)),
            ],
        ),
    ]

The generated code defines a subclass of the django.db.migrations.Migration. It has an operation for creating Customer model table. Call to migrations.CreateModel() method will create a table that allows the underlying database to persist the model.

Run the following Python script to apply the generated migration:
python manage.py migrate customers

The output text:

Operations to perform:
  Apply all migrations: customers
Running migrations:
  Applying customers.0001_initial... OK

Check PostgreSQL Database, now we can see that a table for Customer model was generated and it’s named customers_customer:

Create Serializer class

We need a Serializer class for Customer instances to manage serialization to JSON and deserialization from JSON.

– This CustomerSerializer will inherit from rest_framework.serializers.ModelSerializer superclass.
– ModelSerializer class automatically populates a set of default fields and default validators, we only need to specify the model class.

Now, under customers package, create serializers.py file:

from rest_framework import serializers 
from customers.models import Customer


class CustomerSerializer(serializers.ModelSerializer):

    class Meta:
        model = Customer
        fields = ('id',
                  'name',
                  'age',
                  'active')

Meta inner class declares 2 attributes:
– model: specifies the model related to the serializer
– fields: specifies a tuple of field names that we want to include in the serialization

Create API Views

Open customers/views.py file and declare two functions:
– customer_list(): get list of customers, save a new customer, delete all customers
– customer_detail(): get/update/delete customer by ‘id’
– customer_list_age(): find all customers by ‘age’

from django.shortcuts import render 
from django.http import HttpResponse
from django.http.response import JsonResponse
from django.views.decorators.csrf import csrf_exempt
from rest_framework.parsers import JSONParser 
from rest_framework import status

from customers.models import Customer
from customers.serializers import CustomerSerializer


@csrf_exempt
def customer_list(request):
    if request.method == 'GET':
        customers = Customer.objects.all()
        customers_serializer = CustomerSerializer(customers, many=True)
        return JsonResponse(customers_serializer.data, safe=False)
        # In order to serialize objects, we must set 'safe=False'

    elif request.method == 'POST':
        customer_data = JSONParser().parse(request)
        customer_serializer = CustomerSerializer(data=customer_data)
        if customer_serializer.is_valid():
            customer_serializer.save()
            return JsonResponse(customer_serializer.data, status=status.HTTP_201_CREATED) 
        return JsonResponse(customer_serializer.errors, status=status.HTTP_400_BAD_REQUEST)
    
    elif request.method == 'DELETE':
        Customer.objects.all().delete()
        return HttpResponse(status=status.HTTP_204_NO_CONTENT)


@csrf_exempt 
def customer_detail(request, pk):
    try: 
        customer = Customer.objects.get(pk=pk) 
    except Customer.DoesNotExist: 
        return HttpResponse(status=status.HTTP_404_NOT_FOUND) 
 
    if request.method == 'GET': 
        customer_serializer = CustomerSerializer(customer) 
        return JsonResponse(customer_serializer.data) 
 
    elif request.method == 'PUT': 
        customer_data = JSONParser().parse(request) 
        customer_serializer = CustomerSerializer(customer, data=customer_data) 
        if customer_serializer.is_valid(): 
            customer_serializer.save() 
            return JsonResponse(customer_serializer.data) 
        return JsonResponse(customer_serializer.errors, status=status.HTTP_400_BAD_REQUEST) 
 
    elif request.method == 'DELETE': 
        customer.delete() 
        return HttpResponse(status=status.HTTP_204_NO_CONTENT)

    
@csrf_exempt
def customer_list_age(request, age):
    customers = Customer.objects.filter(age=age)
        
    if request.method == 'GET': 
        customers_serializer = CustomerSerializer(customers, many=True)
        return JsonResponse(customers_serializer.data, safe=False)
        # In order to serialize objects, we must set 'safe=False'

Route Urls to Views functions

Create urls.py in customers folder, now we will define urlpatterns to be matched with request functions in the views.py.

    
from django.conf.urls import url 
from customers import views 
 
urlpatterns = [ 
    url(r'^customers/$', views.customer_list),
    url(r'^customers/(?P[0-9]+)$', views.customer_detail),
    url(r'^customers/age/(?P[0-9]+)/$', views.customer_list_age),
]

Now we must include above URL patterns in root URL configurations.
Open gkzRestApi/urls.py, replace the code:

from django.conf.urls import url, include 
 
urlpatterns = [ 
    url(r'^api/', include('customers.urls')), 
]

Angular Client

Project Structure

We have:
– 4 components: customers-list, customer-details, create-customer, search-customer.
– 3 modules: FormsModule, HttpClientModule, AppRoutingModule.
– customer.ts: class Customer (id, firstName, lastName)
– customer.service.ts: Service for Http Client methods
– app-routing.module.ts: Routing configuration

Setup Angular Project

Create Angular Project

Run command: ng new AngularDjango.

Create Service & Components

On Project folder, run commands below:
– ng g s customer
– ng g c create-customer
– ng g c customer-details
– ng g c customers-list
– ng g c search-customers

On each Component selector, delete app- prefix, then change tslint.json rules – "component-selector" to false.

App Module

Check app.module.ts file, we can see Angular Components & Service are added automatically.
Now we need to import FormsModule, HttpClientModule for using form submission and HTTP requests to Django server. We also import AppRoutingModule for routing (will be created later in this tutorial).

import { BrowserModule } from '@angular/platform-browser';
import { NgModule } from '@angular/core';
import { FormsModule } from '@angular/forms';
import { HttpClientModule } from '@angular/common/http';

import { AppComponent } from './app.component';
import { CreateCustomerComponent } from './create-customer/create-customer.component';
import { CustomerDetailsComponent } from './customer-details/customer-details.component';
import { CustomersListComponent } from './customers-list/customers-list.component';
import { SearchCustomersComponent } from './search-customers/search-customers.component';

import { AppRoutingModule } from './app-routing.module';

@NgModule({
  declarations: [
    AppComponent,
    CreateCustomerComponent,
    CustomerDetailsComponent,
    CustomersListComponent,
    SearchCustomersComponent
  ],
  imports: [
    BrowserModule,
    FormsModule,
    AppRoutingModule,
    HttpClientModule
  ],
  providers: [],
  bootstrap: [AppComponent]
})
export class AppModule { }

Implement Angular Client App

Data Model

Create new file named customer.ts:

export class Customer {
    id: number;
    name: string;
    age: number;
    active: boolean;
}

Data Service

This service uses Angular HttpClient object to make get/post/put/delete request to Django Rest Api Server.

customer.service.ts

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

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

  private baseUrl = 'http://localhost:8000/api/customers';

  constructor(private http: HttpClient) { }

  getCustomer(id: number): Observable<Object> {
    return this.http.get(`${this.baseUrl}/${id}`);
  }

  createCustomer(customer: Object): Observable<Object> {
    return this.http.post(`${this.baseUrl}/`, customer);
  }

  updateCustomer(id: number, value: any): Observable<Object> {
    return this.http.put(`${this.baseUrl}/${id}`, value);
  }

  deleteCustomer(id: number): Observable<any> {
    return this.http.delete(`${this.baseUrl}/${id}`);
  }

  getCustomersList(): Observable<any> {
    return this.http.get(`${this.baseUrl}/`);
  }

  getCustomersByAge(age: number): Observable<any> {
    return this.http.get(`${this.baseUrl}/age/${age}/`);
  }

  deleteAll(): Observable<any> {
    return this.http.delete(`${this.baseUrl}/`);
  }
}

Components

List of Customers

This component calls Data service’s getCustomersList() function, then shows the result as Customer list. It also has deleteCustomers() function that calls Data service’s deleteAll() function to delete all customers.

customers-list/customers-list.component.ts

import { Component, OnInit } from '@angular/core';
import { Observable } from 'rxjs';

import { CustomerService } from '../customer.service';
import { Customer } from '../customer';

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

  customers: Observable;

  constructor(private customerService: CustomerService) { }

  ngOnInit() {
    this.reloadData();
  }

  deleteCustomers() {
    this.customerService.deleteAll()
      .subscribe(
        data => {
          console.log(data);
          this.reloadData();
        },
        error => console.log('ERROR: ' + error));
  }

  reloadData() {
    this.customers = this.customerService.getCustomersList();
  }
}

customers-list/customers-list.component.html

<h1>Customers</h1>

<div *ngFor="let customer of customers | async" style="width: 300px;">
  <customer-details [customer]='customer'></customer-details>
</div>

<div>
  <button type="button" class="button btn-danger" (click)='deleteCustomers()'>Delete All</button>
</div>

This template embeds customer-details component that we will implement right here.

Customer Details

customer-details/customer-details.component.ts

import { Component, OnInit, Input } from '@angular/core';
import { CustomerService } from '../customer.service';
import { Customer } from '../customer';

import { CustomersListComponent } from '../customers-list/customers-list.component';

@Component({
  selector: 'customer-details',
  templateUrl: './customer-details.component.html',
  styleUrls: ['./customer-details.component.css']
})
export class CustomerDetailsComponent implements OnInit {

  @Input() customer: Customer;

  constructor(private customerService: CustomerService, private listComponent: CustomersListComponent) { }

  ngOnInit() {
  }

  updateActive(isActive: boolean) {
    this.customerService.updateCustomer(this.customer.id,
      { name: this.customer.name, age: this.customer.age, active: isActive })
      .subscribe(
        data => {
          console.log(data);
          this.customer = data as Customer;
        },
        error => console.log(error));
  }

  deleteCustomer() {
    this.customerService.deleteCustomer(this.customer.id)
      .subscribe(
        data => {
          console.log(data);
          this.listComponent.reloadData();
        },
        error => console.log(error));
  }

}

As you can see, this component receives input Customer data object from parent component (CustomersListComponent), then apply the information on Data service’s functions: updateCustomer() and deleteCustomer()..

customer-details/customer-details.component.html

<div *ngIf="customer">
  <div>
    <label>Name: </label> {{customer.name}}
  </div>
  <div>
    <label>Age: </label> {{customer.age}}
  </div>
  <div>
    <label>Active: </label> {{customer.active}}
  </div>

  <span class="button is-small btn-primary" *ngIf='customer.active' (click)='updateActive(false)'>Inactive</span>

  <span class="button is-small btn-primary" *ngIf='!customer.active' (click)='updateActive(true)'>Active</span>

  <span class="button is-small btn-danger" (click)='deleteCustomer()'>Delete</span>

  <hr />
</div>

Create Customer

This component uses Data service’s createCustomer() function to save Customer information to the database.

create-customer/create-customer.component.ts

import { Component, OnInit } from '@angular/core';

import { Customer } from '../customer';
import { CustomerService } from '../customer.service';

@Component({
  selector: 'create-customer',
  templateUrl: './create-customer.component.html',
  styleUrls: ['./create-customer.component.css']
})
export class CreateCustomerComponent implements OnInit {

  customer: Customer = new Customer();
  submitted = false;

  constructor(private customerService: CustomerService) { }

  ngOnInit() {
  }

  newCustomer(): void {
    this.submitted = false;
    this.customer = new Customer();
  }

  save() {
    this.customerService.createCustomer(this.customer)
      .subscribe(
        data => {
          console.log(data);
          this.submitted = true;
        },
        error => console.log(error));
    this.customer = new Customer();
  }

  onSubmit() {
    this.save();
  }

}

create-customer/create-customer.component.html

<h3>Create Customer</h3>
<div [hidden]="submitted" style="width: 300px;">
  <form (ngSubmit)="onSubmit()">
    <div class="form-group">
      <label for="name">Name</label>
      <input type="text" class="form-control" id="name" required [(ngModel)]="customer.name" name="name">
    </div>

    <div class="form-group">
      <label for="age">Age</label>
      <input type="text" class="form-control" id="age" required [(ngModel)]="customer.age" name="age">
    </div>

    <button type="submit" class="btn btn-success">Submit</button>
  </form>
</div>

<div [hidden]="!submitted">
  <h4>You submitted successfully!</h4>
  <button class="btn btn-success" (click)="newCustomer()">Add</button>
</div>

Search Customers

This component uses Data services’s getCustomersByAge() function as finder method to find customers by age

search-customers/search-customers.component.ts

import { Component, OnInit } from '@angular/core';
import { Customer } from '../customer';
import { CustomerService } from '../customer.service';

@Component({
  selector: 'search-customers',
  templateUrl: './search-customers.component.html',
  styleUrls: ['./search-customers.component.css']
})
export class SearchCustomersComponent implements OnInit {

  age: number;
  customers: Customer[];

  constructor(private dataService: CustomerService) { }

  ngOnInit() {
    this.age = 0;
  }

  private searchCustomers() {
    this.customers = [];
    this.dataService.getCustomersByAge(this.age)
      .subscribe(customers => this.customers = customers);
  }

  onSubmit() {
    this.searchCustomers();
  }

}

search-customers/search-customers.component.html

<h3>Find By Age</h3>
<div style="width: 300px;">
  <form (ngSubmit)="onSubmit()">
    <div class="form-group">
      <label for="lastname">Age</label>
      <input type="text" class="form-control" id="age" required [(ngModel)]="age" name="age">
    </div>

    <div class="btn-group">
      <button type="submit" class="btn btn-success">Submit</button>
    </div>
  </form>
</div>
<ul>
  <li *ngFor="let customer of customers">
    <h4>{{customer.id}} - {{customer.name}} {{customer.age}}</h4>
  </li>
</ul>

Add Router

app-routing.module.ts

import { NgModule } from '@angular/core';
import { RouterModule, Routes } from '@angular/router';
import { CustomersListComponent } from './customers-list/customers-list.component';
import { CreateCustomerComponent } from './create-customer/create-customer.component';
import { SearchCustomersComponent } from './search-customers/search-customers.component';

const routes: Routes = [
    { path: '', redirectTo: 'customer', pathMatch: 'full' },
    { path: 'customer', component: CustomersListComponent },
    { path: 'add', component: CreateCustomerComponent },
    { path: 'findbyage', component: SearchCustomersComponent },
];

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

export class AppRoutingModule { }

And AppComponent HTML for routing:

app.component.html

<div style="padding: 20px;">
  <h1 style="color: blue">ozenero.com</h1>
  <h3>Angular - Django App</h3>
  <nav>
    <a routerLink="customer" class="btn btn-primary active" role="button" routerLinkActive="active">Customers</a>
    <a routerLink="add" class="btn btn-primary active" role="button" routerLinkActive="active">Add</a>
    <a routerLink="findbyage" class="btn btn-primary active" role="button" routerLinkActive="active">Search</a>
  </nav>
  <router-outlet></router-outlet>
</div>

Run & Check Results

– Run Django server with command: python manage.py runserver.
– Run Angular App with command: ng serve.
– Open browser for url http://localhost:4200/:

Add Customer:

Check database after saving Customers:

Show Customers:

Click on Active button to update Customer status:

Check database after updating:

Search Customers by Age:

Delete a Customer:

Check database after deleting a Customer:

Delete All Customers:

Now the table is empty:

Source Code

– Django-RestApi-server-PostgreSQL
– AngularDjango-PostgreSQL