What is CRUD?

What is CRUD?

CRUD stands for Create, Read, Update & Delete. These are the four basic operations which are executed on Database Models. We are developing a web app which is capable of performing these operations.

Since we are developing a library app, let’s take an example of the same. In a library, books are objects. The books have attributes like name, author, etc. We need an application which can perform CRUD operations on book object. The CRUD operations are defined as follows:

1. Read Operation

   The ability of the application to read data from the database.

2. Create Operation

   The ability of the application to store data in the database.

3. Update Operation

   The ability of the application to edit the stored value in the database.

4. Delete Operation

   The ability of the application to delete the value in the database.

We are going to develop the operations in the same order.

Majority of applications on the internet are CRUD applications. For example – Facebook uses CRUD operations to save your data on their database. You can change your profile picture that means perform the update operation. Of course, you can see the data in-app or browser which is read operation.

Django CRUD Tutorial

Let’s explore the steps to design a CRUD application in Django framework:

1. Making a Library CRUD Application

   Our first steps would be to make a new project in Django and a new virtual environment. To make a virtual environment, enter:

2. Installing Application and Other Important Settings

   To install the app, just add the application’s name in the INSTALLED_APPS list. This is inside settings.py file.

   Once you complete this step, we also need to establish the Static Files Settings. Copy these settings as it is and replace it with the existing settings of your project.

   Code:

   # Ducatindia Static Files Settings
   STATIC_URL = '/static/'
   STATIC_ROOT = os.path.join(BASE_DIR, 'static-files')
   #Ducatindia #User_Uploaded_Files
   MEDIA_URL = 'media/'
   MEDIA_ROOT=os.path.join(BASE_DIR, 'media')
   

3. Making Models for Books App

   In the book folder, open models.py and paste this code. We are making a model or database table for our books app.

   Code:

   from django.db import models
   #Ducatindia Models
   classBook(models.Model):
   name = models.CharField(max_length = 50)
   picture = models.ImageField()
   author = models.CharField(max_length = 30, default=’anonymous’)
   email = models.EmailField(blank = True)
   describe = models.TextField(default = ‘DataFlair Django tutorials’)
   def__str__(self):
   return self.name
   

4. Making Model Forms in Book Directory

   Django makes it so much easier to make forms for models. We just need to use our models and we can easily make forms.

   Make a new file forms.py in book directory. Paste this code in this forms.py.

   Code:

   from django import forms
   from .models import Book
   #Ducatindia
   classBookCreate(forms.ModelForm):
   class Meta:
   model = Book
   fields = '__all__'
   

5. 5. Registering Model in Django Admin

   Here we are editing admin.py existing in book folder. Import the model you want to register in the admin. In this case, it is a Book.

   Then paste this line below it.

   Code:

   admin.site.register(Book)

6. Making View Functions for Django CRUD App

   The view functions are our actual CRUD operations in Django. Now, we are editing views.py in book folder. Open views.py file in the folder. Paste this code in it:

   Code:

   from django.shortcuts import render, redirect
   from .models import Book
   from .forms import BookCreate
   from django.http import HttpResponse
   #Ducatindia
   defindex(request):
   shelf = Book.objects.all()
   returnrender(request, 'book/library.html', {'shelf': shelf})
   defupload(request):
   upload = BookCreate()
   if request.method == 'POST':
   upload = BookCreate(request.POST, request.FILES)
   if upload.is_valid():
   upload.save()
   returnredirect('index')
   else:
   returnHttpResponse("""your form is wrong, reload on < a href = "{{ url :'index'}}">reload< /a>""")
   else:
   returnrender(request, 'book/upload_form.html', {'upload_form':upload})
   defupdate_book(request, book_id):
   book_id = int(book_id)
   try:
   book_sel = Book.objects.get(id = book_id)
   except Book.DoesNotExist:
   returnredirect('index')
   book_form = BookCreate(request.POST or None, instance = book_sel)
   if book_form.is_valid():
   book_form.save()
   returnredirect('index')
   returnrender(request, 'book/upload_form.html', {'upload_form':book_form})
   defdelete_book(request, book_id):
   book_id = int(book_id)
   try:
   book_sel = Book.objects.get(id = book_id)
   except Book.DoesNotExist:
   returnredirect('index')
   book_sel.delete()
   returnredirect('index')
   

7. Making Templates

   The first thing you need to do is to make the templates folder in the book folder. Inside book/templates, make another folder book. We are going to make all our templates in that folder.

   Inside book/templates/book, make a new file:

   < !DOCTYPE html>
   {% load static %}
   < html>
   < head>
   < title>Books App< /title>
   < link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.3.1/css/bootstrap.min.css"
   integrity="sha384-ggOyR0iXCbMQv3Xipma34MD+dH/1fQ784/j6cY/iJTQUOhcWr7x9JvoRxT2MZw1T" crossorigin="anonymous">
   < /head>
   < body style="background-color:#4DB6AC;">
   < nav class="navbar navbar-light" style="background-color:#FF0033;">
   < a href="#" class="navbar-brand" style="background-color:#FFCC33;color:#000000;border-width:10px;border-color:#FFCC33;border-style:solid;border-spacing:30px;border-radius: 5px;">Library App< /a>
   < a class="navbar-link btn-lg" href="{% url 'index' %}" style="background-color:#FFCC33;color:#000000;">DataFlair< /a>
   < a href="{% url 'admin:index' %}" class = 'navbar-link btn-lg' style="background-color:#FFCC33;color:#000000;">Admin< /a>
   < a href="{% url 'upload-book' %}" class="navbar-link btn-lg" style="background-color:#FFCC33;color:#000000;">Upload Books< /a>
   < /nav>
   < br>
   {% block content %}
   < div class="card-columns">
   {% for book in shelf %}
   < div class="card" style="width: 18rem;">
   < img class="card-img-top" src="{{ book.picture.url }}">
   < div class="card-body">
   < h5 class="card-title">{{ book.name }}< /h5>
   < p class="card-text">{{ book.describe }}< /p>
   < div class="card-footer bg-transparent border-dark">
   < p class="card-title">{{book.author}}< /p>
   < center>
   < a href="update/{{book.id}}" class="btn btn-warning" id = '{{book.id}}'>edit< /a>
   < a href="delete/{{book.id}}" class="btn btn-danger" id = '{{book.id}}'>delete< /a>
   < /center>
   < /div>
   < /div>
   < /div>
   {% endfor %}
   < /div>
   {% endblock %}
   < /body>
   < /html>
   

8. Configuring URLs

   Now, we need to configure the urls file. Paste this code as it is in the mentioned urls files. If the file doesn’t exist then make one and copy the whole thing.

   Code:

   from django.contrib import admin
   from django.urls import path, include
   #Ducatindia
   urlpatterns = [
   path('admin/', admin.site.urls),
   path('', include('book.urls'))
   ]
   

   Code:

   from django.urls import path
   from . import views
   from libraryapp.settings import DEBUG, STATIC_URL, STATIC_ROOT, MEDIA_URL, MEDIA_ROOT
   from django.conf.urls.static import static
   urlpatterns = [
   path('', views.index, name = 'index'),
   path('upload/', views.upload, name = 'upload-book'),
   path('update/< int:book_id>', views.update_book),
   path('delete/< int:book_id>', views.delete_book)
   ]
   #Ducatindia
   if DEBUG:
   urlpatterns += static(STATIC_URL, document_root = STATIC_ROOT)
   urlpatterns += static(MEDIA_URL, document_root = MEDIA_ROOT)
   

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