Process request and process response in Django - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a request in Django?

A request is an object that Django receives from a user’s browser. It contains all the information about what the user wants, like the URL, form data, and headers.

beginner

What does Django use to send data back to the user?

Django sends a response object back to the user’s browser. This response contains the content to display, like HTML, JSON, or a redirect.

intermediate

How does Django handle a request internally?

Django takes the request, matches its URL to a view function, runs that function, and then returns the response generated by the view.

intermediate

What is the role of middleware in processing requests and responses?

Middleware is code that runs before and after the view. It can modify the request before it reaches the view or change the response before it goes back to the user.

beginner

What is the difference between request.GET and request.POST?

request.GET holds data sent in the URL query string, usually from links or forms with method GET. request.POST holds data sent in the body of a POST request, usually from forms that submit data.

What does Django use to decide which code runs for a request?

A Database schema

B URL routing

C Template engine

D Middleware stack

Django uses URL routing to match the request URL to the correct view function.

Which object contains the data sent by the user in a form submission?

A request.GET

B response.content

C request.POST

D request.META

request.POST contains form data sent via POST method.

What can middleware do in Django?

A Modify both request and response

B Only modify the response

C Only modify the request

D Only handle database queries

Middleware can modify both the request before the view and the response after the view.

What type of object does a Django view return?

A Request object

B Middleware object

C Template object

D Response object

A Django view returns a response object that is sent back to the user.

Where does Django store HTTP headers from the request?

A request.META

B request.headers

C request.POST

D response.headers

HTTP headers are stored in request.META as a dictionary.

Explain the journey of a user request through Django until a response is sent back.

Think about what happens from when you type a URL to when you see a page.

Describe how you can access form data sent by a user in Django.

Consider the HTTP methods and where data is stored in the request object.

Practice

1. What does the request object in a Django view primarily contain?

easy

A. Information sent by the user, like form data and headers

B. The HTML template to render

C. The final content sent back to the user

D. Database connection details

Solution

1. Step 1: Understand the role of the request object

   The request object holds all data sent by the user, such as form inputs, cookies, and headers.

2. Step 2: Differentiate request from response

   The response object is what the server sends back, not the request.

3. Final Answer:

   Information sent by the user, like form data and headers -> Option A

4. Quick Check:

   Request = User data [OK]

Hint: Request holds user input; response sends output [OK]

Common Mistakes:

• Confusing request with response
• Thinking request contains templates
• Assuming request holds server data

2. Which of the following is the correct way to return a simple text response in a Django view?

easy

A. return HttpResponse('Hello World')

B. return render('Hello World')

C. return JsonResponse('Hello World')

D. return redirect('Hello World')

Solution

1. Step 1: Identify the correct response class for text

   HttpResponse is used to send plain text or HTML content back to the user.

2. Step 2: Check other options

   render is for templates, JsonResponse for JSON data, redirect for URL redirects.

3. Final Answer:

   return HttpResponse('Hello World') -> Option A

4. Quick Check:

   Text response uses HttpResponse [OK]

Hint: Use HttpResponse for plain text output [OK]

Common Mistakes:

• Using render without a template
• Using JsonResponse for plain text
• Confusing redirect with response content

3. Given this Django view code, what will be the output when accessed?

from django.http import JsonResponse

def my_view(request):
    data = {'name': 'Alice', 'age': 30}
    return JsonResponse(data)

medium

A. name=Alice&age=30

B. {'name': 'Alice', 'age': 30}

C. {"name": "Alice", "age": 30}

D. An error because JsonResponse needs a string

Solution

1. Step 1: Understand JsonResponse output format

   JsonResponse converts the Python dictionary into a JSON string with double quotes.

2. Step 2: Check the output format

   The output is a JSON string: {"name": "Alice", "age": 30} with double quotes, not Python dict syntax.

3. Final Answer:

   {"name": "Alice", "age": 30} -> Option C

4. Quick Check:

   JsonResponse outputs JSON string [OK]

Hint: JsonResponse outputs JSON with double quotes [OK]

Common Mistakes:

• Expecting Python dict syntax in output
• Confusing URL query string with JSON
• Thinking JsonResponse needs string input

4. What is wrong with this Django view code?

from django.http import HttpResponse

def bad_view(request):
    response = HttpResponse('Hello')
    response.status_code = '404'
    return response

medium

A. HttpResponse cannot have status_code set manually

B. status_code must be an integer, not a string

C. Missing return statement

D. HttpResponse requires a JSON object

Solution

1. Step 1: Check the status_code assignment

   Status codes must be integers like 404, not strings like '404'.

2. Step 2: Confirm HttpResponse usage

   HttpResponse allows setting status_code manually but it must be int.

3. Final Answer:

   status_code must be an integer, not a string -> Option B

4. Quick Check:

   status_code = int, not string [OK]

Hint: status_code must be int, not string [OK]

Common Mistakes:

• Using string for status_code
• Thinking HttpResponse forbids status_code
• Forgetting to return response

5. You want to create a Django view that processes a POST request with JSON data and returns a JSON response with a message and the original data. Which code snippet correctly handles this?

hard

A. def view(request):
data = request.GET
return JsonResponse({'message': 'Received', 'data': data})

B. def view(request):
data = request.POST
return HttpResponse({'message': 'Received', 'data': data})

C. def view(request):
data = request.body
return JsonResponse(data)

D. def view(request):
data = json.loads(request.body)
return JsonResponse({'message': 'Received', 'data': data})

Solution

1. Step 1: Parse JSON from POST request body

   request.body contains raw bytes; json.loads converts it to a Python dict.

2. Step 2: Return JsonResponse with message and data

   JsonResponse correctly serializes the Python dict to JSON for response.

3. Step 3: Check other options

   def view(request): data = request.POST return HttpResponse({'message': 'Received', 'data': data}) wrongly uses HttpResponse with dict, def view(request): data = request.GET return JsonResponse({'message': 'Received', 'data': data}) uses GET instead of POST, def view(request): data = request.body return JsonResponse(data) returns raw bytes without parsing.

4. Final Answer:

   def view(request): data = json.loads(request.body) return JsonResponse({'message': 'Received', 'data': data}) -> Option D

5. Quick Check:

   Parse JSON body, respond with JsonResponse [OK]

Hint: Parse JSON from request.body, respond with JsonResponse [OK]

Common Mistakes:

• Using request.POST for JSON body
• Returning dict in HttpResponse
• Not parsing JSON before response