Django CRUD Operations: Step-by-Step Guide

This tutorial assumes you have already created your project (todo_site) and your app (tasks), and registered the app in settings.py. We will now build the CRUD functionality one operation at a time.

Step 0: The Foundation (Model)

Before we can do any CRUD operations, we need a database table to hold our data.

1. Define the Model in tasks/models.py:

   from django.db import models
   
   class Task(models.Model):
       title = models.CharField(max_length=200)
       completed = models.BooleanField(default=False)
       created_at = models.DateTimeField(auto_now_add=True)
   
       def __str__(self):
           return self.title
   

2. Create the Database Table: Run this in your terminal:

   python manage.py makemigrations
   python manage.py migrate
   

Operation 1: READ (Displaying the List)

The "R" in CRUD. Let's just get a list of tasks showing up on the screen.

1. Create the View (tasks/views.py): We fetch all tasks from the database and send them to the template.

   from django.shortcuts import render
   from .models import Task
   
   def task_list(request):
       tasks = Task.objects.all()  # Fetch all data
       return render(request, 'tasks/list.html', {'tasks': tasks})
   

2. Create the URL (todo_list/urls.py): Map the empty path '' to our view.

   from django.urls import path, include
   from . import views
   
   urlpatterns = [
       path('', include('tasks.urls')),
   ]
   

3. Create the URL (tasks/urls.py): Map the empty path '' to our view.

   from django.urls import path
   from . import views
   
   urlpatterns = [
       path('', views.task_list, name='list'),
   ]
   

4. Create the Template (templates/tasks/list.html): A simple HTML loop to display data.

   <h1>My To-Do List</h1>
   <ul>
       {% for task in tasks %}
           <li>{{ task.title }}</li>
       {% empty %}
           <li>No tasks yet!</li>
       {% endfor %}
   </ul>
   

Checkpoint: Run python manage.py runserver and go to http://127.0.0.1:8000/. You should see "My To-Do List" and "No tasks yet!".

Operation 2: CREATE (Adding Data)

The "C" in CRUD. Now we need a form to add new tasks.

1. Define the Form (tasks/forms.py): Create this file to let Django handle the HTML form generation.

   from django import forms
   from .models import Task
   
   class TaskForm(forms.ModelForm):
       class Meta:
           model = Task
           fields = ['title', 'completed']
   

2. Update the View (tasks/views.py): Modify task_list to handle data submission (POST requests).

   from django.shortcuts import render, redirect # Import redirect
   from .models import Task
   from .forms import TaskForm # Import the Form
   
   def task_list(request):
       tasks = Task.objects.all()
       form = TaskForm() # Empty form for GET request
   
       if request.method == 'POST':
           form = TaskForm(request.POST) # Fill form with data
           if form.is_valid():
               form.save()  # Save to database
               return redirect('list') # Refresh page
   
       return render(request, 'tasks/list.html', {'tasks': tasks, 'form': form})
   

3. Update the Template (templates/tasks/list.html): Add the form code above the list.

   <h1>My To-Do List</h1>
   
   <!-- New Form Section -->
   <form method="POST">
       {% csrf_token %}
       {{ form.as_p }}
       <button type="submit">Add Task</button>
   </form>
   
   <hr>
   
   <ul>
       {% for task in tasks %}
           <li>{{ task.title }}</li>
       {% endfor %}
   </ul>
   

Checkpoint: Refresh your browser. You can now type a task title, click "Add Task", and see it appear in the list immediately.

Operation 3: UPDATE (Editing Data)

The "U" in CRUD. We need a dedicated page to edit a specific task.

1. Create the View (tasks/views.py): We need a new view that finds a specific task by its ID (pk) and fills the form with existing data.

   # Add 'get_object_or_404' to imports
   from django.shortcuts import render, redirect, get_object_or_404
   
   # ... existing task_list view ...
   
   def task_update(request, pk):
       task = get_object_or_404(Task, id=pk) # Find task by ID
       form = TaskForm(instance=task) # Fill form with existing data
   
       if request.method == 'POST':
           form = TaskForm(request.POST, instance=task)
           if form.is_valid():
               form.save()
               return redirect('list')
   
       return render(request, 'tasks/update.html', {'form': form})
   

2. Create the URL (tasks/urls.py): We need a URL that accepts an ID number (like update/1/).

   urlpatterns = [
       path('', views.task_list, name='list'),
       # New URL pattern
       path('update/<int:pk>/', views.task_update, name='update'),
   ]
   

3. Create the Template (templates/tasks/update.html): A separate page just for editing.

   <h2>Update Task</h2>
   <form method="POST">
       {% csrf_token %}
       {{ form.as_p }}
       <button type="submit">Update</button>
   </form>
   

4. Link it in the List (templates/tasks/list.html): Add an "Edit" link next to each item.

   <li>
       {{ task.title }}
       <a href="{% url 'update' task.id %}">Edit</a> <!-- New Link -->
   </li>
   

Checkpoint: Refresh the home page. Click "Edit" next to a task. You will go to a new page, change the title or checkbox, click Update, and return to the home page with the changes saved.

Operation 4: DELETE (Removing Data)

The "D" in CRUD. Ideally, we ask for confirmation before deleting.

1. Create the View (tasks/views.py): Find the task, wait for a POST (confirmation) request, then delete.

   # ... existing views ...
   
   def task_delete(request, pk):
       task = get_object_or_404(Task, id=pk)
   
       if request.method == 'POST':
           task.delete() # Delete from database
           return redirect('list')
   
       return render(request, 'tasks/delete_confirm.html', {'task': task})
   

2. Create the URL (tasks/urls.py):

   urlpatterns = [
       path('', views.task_list, name='list'),
       path('update/<int:pk>/', views.task_update, name='update'),
       # New URL pattern
       path('delete/<int:pk>/', views.task_delete, name='delete'),
   ]
   

3. Create the Template (templates/tasks/delete_confirm.html): A warning page.

   <h2>Are you sure?</h2>
   <p>Do you want to delete "{{ task.title }}"?</p>
   
   <form method="POST">
       {% csrf_token %}
       <button type="submit">Yes, Delete</button>
       <a href="{% url 'list' %}">Cancel</a>
   </form>
   

4. Link it in the List (templates/tasks/list.html): Add a "Delete" link next to the Edit link.

   <li>
       {{ task.title }}
       <a href="{% url 'update' task.id %}">Edit</a>
       <a href="{% url 'delete' task.id %}">Delete</a> <!-- New Link -->
   </li>