Development server and runserver in Django

Introduction

The development server lets you see your Django website while you build it. It runs your site on your computer so you can test and fix things easily.

When you want to check how your website looks and works during development.

When you need to test new features or changes before making the site live.

When you want to quickly see error messages and debug your code.

When you are learning Django and want to try out code changes immediately.

When you want to share your local site temporarily on your network.

Syntax

Django

python manage.py runserver [optional_port]

You run this command in your project folder where manage.py is located.

If you don't give a port, it uses 8000 by default (like http://127.0.0.1:8000/).

Examples

Starts the server on the default address and port (127.0.0.1:8000).

Django

python manage.py runserver

Starts the server on port 8080 instead of 8000.

Django

python manage.py runserver 8080

Makes the server available on all network interfaces, so others on your network can access it.

Django

python manage.py runserver 0.0.0.0:8000

Sample Program

This command starts the Django development server on your local machine at http://127.0.0.1:8000/. You can open this address in your browser to see your website as you build it.

Django

python manage.py runserver

Important Notes

The development server is for testing only. It is not secure or fast enough for real users.

If you change your code, the server reloads automatically so you see updates right away.

Use CONTROL-C in the terminal to stop the server when you are done.

Summary

The runserver command starts a simple web server on your computer.

It helps you see and test your Django site during development.

You can choose the port and make it accessible on your network if needed.

Practice

1. What does the Django runserver command do?

easy

A. Deploys your Django site to the internet permanently

B. Creates a new Django project automatically

C. Starts a simple web server to test your site during development

D. Compiles your Django code into an executable file

Solution

1. Step 1: Understand the purpose of runserver

   The runserver command is used to start a lightweight web server on your local machine.

2. Step 2: Identify what runserver is NOT

   It does not deploy your site permanently, create projects, or compile code; it only runs a development server.

3. Final Answer:

   Starts a simple web server to test your site during development -> Option C

4. Quick Check:

   runserver = starts local test server [OK]

Hint: Remember runserver means run a local test server [OK]

Common Mistakes:

• Thinking runserver deploys the site permanently
• Confusing runserver with project creation commands
• Assuming runserver compiles code

2. Which of the following is the correct command to start the Django development server on port 8080?

easy

A. python manage.py run 8080

B. python manage.py runserver 8080

C. python manage.py startserver 8080

D. python manage.py runserver -p 8080

Solution

1. Step 1: Recall the correct syntax for runserver with port

   The correct syntax is python manage.py runserver <port>, so python manage.py runserver 8080 is valid.

2. Step 2: Identify incorrect options

   Options A, B, and C use wrong flags or commands that do not exist in Django.

3. Final Answer:

   python manage.py runserver 8080 -> Option B

4. Quick Check:

   runserver + port number = correct syntax [OK]

Hint: Use runserver followed by port number without flags [OK]

Common Mistakes:

• Using -p flag which Django does not support
• Typing startserver instead of runserver
• Omitting manage.py or using wrong command

3. What will happen if you run python manage.py runserver 0.0.0.0:8000?

medium

A. The server will start and be accessible on all network interfaces

B. The server will start and be accessible only on localhost

C. The command will cause a syntax error

D. The server will start but only on port 80

Solution

1. Step 1: Understand the IP address 0.0.0.0 in runserver

   Using 0.0.0.0 tells Django to listen on all network interfaces, not just localhost.

2. Step 2: Confirm the port number usage

   The port 8000 is explicitly set, so the server listens on port 8000 on all interfaces.

3. Final Answer:

   The server will start and be accessible on all network interfaces -> Option A

4. Quick Check:

   0.0.0.0 means all interfaces [OK]

Hint: 0.0.0.0 means listen on all network interfaces [OK]

Common Mistakes:

• Thinking 0.0.0.0 restricts to localhost
• Assuming port changes to 80 automatically
• Expecting syntax error from this command

4. You run python manage.py runserver 9000 but get an error saying the port is already in use. What should you do?

medium

A. Choose a different port number and run the command again

B. Restart your computer and run the same command again

C. Change the command to python manage.py runserver --force 9000

D. Uninstall Django and reinstall it

Solution

1. Step 1: Understand the port in use error

   This error means another program is using port 9000, so Django cannot start the server there.

2. Step 2: Choose a different port number

   To fix this, pick a free port (like 8000 or 8080) and run python manage.py runserver <new_port>.

3. Final Answer:

   Choose a different port number and run the command again -> Option A

4. Quick Check:

   Port in use? Pick another port [OK]

Hint: If port busy, pick another port number [OK]

Common Mistakes:

• Trying non-existent --force flag
• Unnecessarily reinstalling Django
• Assuming restart fixes port conflicts always

5. You want to test your Django site on your phone connected to the same Wi-Fi. Which command lets you run the server so your phone can access it?

hard

A. python manage.py runserver --external 8000

B. python manage.py runserver 127.0.0.1:8000

C. python manage.py runserver localhost:8000

D. python manage.py runserver 0.0.0.0:8000

Solution

1. Step 1: Understand network accessibility for runserver

   Using 127.0.0.1 or localhost restricts access to your computer only, so other devices cannot connect.

2. Step 2: Use 0.0.0.0 to allow external devices

   Running python manage.py runserver 0.0.0.0:8000 makes the server listen on all interfaces, allowing your phone on the same Wi-Fi to connect.

3. Step 3: Identify invalid options

   python manage.py runserver --external 8000 uses a non-existent flag --external, so it will cause an error.

4. Final Answer:

   python manage.py runserver 0.0.0.0:8000 -> Option D

5. Quick Check:

   0.0.0.0 allows external access [OK]

Hint: Use 0.0.0.0 to allow devices on your network [OK]

Common Mistakes:

• Using localhost or 127.0.0.1 which blocks external devices
• Trying unsupported flags like --external
• Not connecting phone to same Wi-Fi network