makemigrations and migrate commands in Django - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

What does the makemigrations command do in Django?

Choose the correct description of what happens when you run python manage.py makemigrations.

A It resets the database to its initial empty state.

B It applies all pending migrations to the database.

C It creates migration files based on changes detected in your models.

D It deletes all existing migration files in the project.

💡 Hint

Think about which command prepares changes but does not apply them yet.

The makemigrations command looks at your Django models and creates migration files that describe the changes. It does not change the database itself.

🧠 Conceptual

intermediate

What is the purpose of the migrate command in Django?

Select the correct explanation of what python manage.py migrate does.

A It creates new migration files from model changes.

B It applies migration files to update the database schema.

C It deletes all migration files and resets the database.

D It generates a new Django project with migrations.

💡 Hint

This command changes the database structure based on migration files.

The migrate command reads migration files and applies them to the database, updating tables and schema accordingly.

❓ component_behavior

advanced

What will happen if you run migrate without running makemigrations after changing models?

Consider you changed a model but only run python manage.py migrate. What is the outcome?

A The database schema updates to match the model changes automatically.

B The old migration files are deleted and replaced.

C An error occurs because migrations are missing.

D No changes are applied because no new migration files exist.

💡 Hint

Think about what migrate uses to update the database.

Without new migration files created by makemigrations, migrate has no instructions to apply, so the database stays unchanged.

🔧 Debug

advanced

You ran makemigrations but no migration file was created. What could be the reason?

Which of the following is the most likely cause for makemigrations not generating a migration file?

A You forgot to add the app to <code>INSTALLED_APPS</code> in settings.

B You ran <code>migrate</code> before <code>makemigrations</code>.

C You deleted all migration files manually.

D You changed the database directly without updating models.

💡 Hint

Django only tracks models for apps listed in settings.

If the app is not listed in INSTALLED_APPS, Django ignores its models and does not create migrations.

📝 Syntax

expert

What error will this command produce if run in a Django project with no migrations folder?
python manage.py migrate

Assuming the project has no migrations folder or migration files yet, what will happen when you run python manage.py migrate?

A It will apply built-in Django migrations for default apps but skip missing app migrations.

B It will raise a <code>ModuleNotFoundError</code> because migrations are missing.

C It will raise a <code>django.db.migrations.exceptions.MigrationSchemaMissing</code> error.

D It will create the migrations folder and apply initial migrations automatically.

💡 Hint

Django has built-in migrations for its core apps.

Even if your app has no migrations, Django applies migrations for built-in apps like auth and admin. It does not error if your app lacks migrations.

Practice

1. What is the main purpose of the makemigrations command in Django?

easy

A. To delete old migration files

B. To apply changes to the database

C. To start the Django development server

D. To create migration files that describe changes in models

Solution

1. Step 1: Understand the role of makemigrations

   This command generates files that describe changes made to Django models, like adding or removing fields.

2. Step 2: Differentiate from migrate

   migrate applies those changes to the database, but makemigrations only creates the description files.

3. Final Answer:

   To create migration files that describe changes in models -> Option D

4. Quick Check:

   makemigrations creates files = A [OK]

Hint: Remember: makemigrations creates files, migrate applies them [OK]

Common Mistakes:

• Confusing makemigrations with migrate
• Thinking makemigrations changes the database directly
• Assuming makemigrations starts the server

2. Which of the following is the correct command to apply migrations to the database in Django?

easy

A. python manage.py makemigrations

B. python manage.py migrate

C. python manage.py runserver

D. python manage.py makemigrate

Solution

1. Step 1: Identify the command to apply migrations

   The command python manage.py migrate applies migration files to update the database schema.

2. Step 2: Check other options

   makemigrations creates migration files, runserver starts the server, and makemigrate is not a valid command.

3. Final Answer:

   python manage.py migrate -> Option B

4. Quick Check:

   Apply migrations = migrate = A [OK]

Hint: Use migrate to apply changes, not makemigrations [OK]

Common Mistakes:

• Typing makemigrate instead of migrate
• Using makemigrations to update the database
• Confusing runserver with migration commands

3. Given the following sequence of commands in a Django project:

python manage.py makemigrations
python manage.py migrate

What will happen after running these commands?

medium

A. The database schema will be updated to match the current models

B. The server will start running

C. Migration files will be deleted

D. The models will be reset to default

Solution

1. Step 1: Understand the effect of makemigrations

   This command creates migration files describing model changes.

2. Step 2: Understand the effect of migrate

   This command applies those migration files to update the database schema accordingly.

3. Final Answer:

   The database schema will be updated to match the current models -> Option A

4. Quick Check:

   makemigrations + migrate = update DB schema = C [OK]

Hint: makemigrations then migrate updates database schema [OK]

Common Mistakes:

• Thinking migrate starts the server
• Believing migration files get deleted automatically
• Assuming models reset after migrations

4. You ran python manage.py migrate but got an error saying "No migrations to apply." What is the most likely cause?

medium

A. You forgot to run makemigrations to create migration files

B. The database is corrupted

C. You need to restart the Django server

D. Your models have syntax errors

Solution

1. Step 1: Analyze the error message

   "No migrations to apply" means Django found no new migration files to run.

2. Step 2: Identify the missing step

   If you did not run makemigrations, no migration files exist to apply.

3. Final Answer:

   You forgot to run makemigrations to create migration files -> Option A

4. Quick Check:

   No migrations found = forgot makemigrations = D [OK]

Hint: Run makemigrations before migrate to create migration files [OK]

Common Mistakes:

• Restarting server instead of creating migrations
• Assuming database corruption without checking migrations
• Ignoring missing migration files

5. You added a new field to a Django model but forgot to run makemigrations. Later, you run python manage.py migrate. What will happen?

hard

A. The new field will be added to the database automatically

B. An error will occur because migration files are missing

C. Nothing changes in the database schema

D. Django will create migration files automatically and apply them

Solution

1. Step 1: Understand the role of makemigrations

   This command creates migration files describing model changes like new fields.

2. Step 2: Effect of running migrate without new migration files

   If no migration files exist, migrate finds nothing to apply, so the database stays unchanged.

3. Final Answer:

   Nothing changes in the database schema -> Option C

4. Quick Check:

   No migration files = migrate does nothing = B [OK]

Hint: Always run makemigrations after model changes before migrate [OK]

Common Mistakes:

• Expecting migrate to detect model changes automatically
• Assuming migrate creates migration files
• Thinking database updates without migration files