Welcome to the section on retrieving a single record by its ID using Django ORM. Previously, we explored how to retrieve all records from a database. Now, we'll zoom in and focus on fetching a specific record. This is an essential skill for many real-world applications where you need detailed information about a particular item.

In this lesson, you'll learn how to retrieve a single record from the database using its ID. This is a common scenario when the user needs to view or interact with detailed data about a single item.

We'll work with the Todo model that we used previously:

Python
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1from django.db import models
2
3class Todo(models.Model):
4    task = models.CharField(max_length=200)
5    completed = models.BooleanField(default=False)
6
7    def __str__(self):
8        return self task

To retrieve a specific Todo item by ID, we'll use the get() method of the Django ORM. This method allows us to fetch a single record based on a specific field value, such as the primary key (ID).

Python
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1from django.http import JsonResponse
2from django.shortcuts import get_object_or_404
3from .models import Todo
4
5def get_todo(request, id):
6    try:
7        todo = Todo.objects.get(id=id)
8        return JsonResponse({'id': todo.id, 'task': todo.task})
9    except Todo.DoesNotExist:
10        return JsonResponse({'message': 'Todo not found'}, status=404)

This function checks if a Todo with the given ID exists. If it does, it retrieves the Todo object and returns its details as a JSON response.

There is also a shortcut method get_object_or_404() that simplifies this process. It retrieves the object if it exists, or raises a 404 error if not found.

Python
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1def get_todo(request, id):
2    todo = get_object_or_404(Todo, id=id)
3    return JsonResponse({'id': todo.id, 'task': todo.task})

In this case, if the element with the given ID is not found, a 404 error will be raised automatically and 404 page will be displayed.

Learning how to retrieve a single record by its ID is vital for building interactive and user-friendly applications. Consider scenarios like:

• Viewing the details of a specific product on an e-commerce site.
• Displaying a single blog post on a news website.
• Showing detailed information about a task in a to-do list application.

Being able to fetch and display precise data improves the user experience by allowing users to see the information they need quickly and efficiently. It's a fundamental skill that will make your Django applications more responsive and dynamic.

Ready to get started? Let's move on to the practice section and apply the concepts we've discussed. With hands-on practice, you'll build your confidence in retrieving single records by ID. Happy coding!