Empty Migrations and Feature Development

Description

How I learned about Django Empty Migrations while working on a feature for my app.

Published

Published Date

Feb 8, 2026

slug

understanding-django-empty-migrations

I had previously developed a feature called “Bookmarking” in Open Past Paper. This was one of most requested features by my users. This helped a lot of the users keep track of what questions they wanted to come back in the future for further study.

manishgotameFeature: Question Bookmarks & Activity History - Open Past Paper

Feature: Question Bookmarks & Activity History - Open Past Paper

Easily save questions and track previously solved ones with the new Bookmarks and Last Viewed features.

And while I was happy with my implementation, some “power users” were not satisfied. So I started seeing a lot of them asking different versions of “Bookmarking” such as a Completion checkbox, Hard tags etc.

At first, this seems like a simple task to add a check box but if you look at it from a product development perspective, you want to categorize these kinds of feature requests and figure out whether to build it. One of the many things I learned while developing software at startups is that we have be strategic to choose what to build, so as to not clutter the whole product down the line because the growth of an app relies on how quickly a user can be onboarded. You add too many features and the user will get lost and eventually churn.

However, this feature request seemed like something that can be an improvement on an existing feature. So I decided to improve the bookmarking feature to support folder where users can create new folders such as “Hard”, “Complete”, “Unable to Solve” and add questions as required. This seemed like the right feature to improve.

Let’s try to go deeper into technical implementation and the hurdles I encountered.

I drew a simple Entity Relationship Diagram (ERD) for the tables and how they might relate, before actually diving into the implementation.

While the implementation seems pretty straightforward:

You create a new Folder Table and many the 1:Many relationship from User to Folder and then the similarly a M:M relationship with the Questions table.

Migrate the database.

But this is to be done in a live application handling over 10,000 users. So we need to migrate the database and somehow store the existing bookmarked questions in default folder so the previous users’ data is not lost.

This is where the concept of empty migrations comes into play.

An empty migration in Django is a migration file that does not automatically detect any model changes, but is still created so we can manually add database operations or custom logic.

So, the idea is to create an empty migrations file and add a custom logic to:

Create a default folder called Uncategorized.

Move all the previously saved questions into that folder.

Update the database with that logic.

Step 1: Create and Update existing Tables.

`Folder` Table

`Saved Question` Table

I also added a signal which automatically creates a default Uncategorized folder during user creation:

So the flow should be something like this:

Step 2: Empty Migrations

Now the hardest part is to migrate the database and assign the existing Saved Questions into this Uncategorized Folder.

Add all the New Table Schema:

Recreate the data migration with an empty migration file.

Few things:

This creates an empty migrate file with no changes to the database schema.

It creates a file which allows us to add our own separate function

Empty migration file:

Now we add our function which creates a default folder called Uncategorized for every existing user and then updates all the Saved question to belong to that Uncategorized folder.

Then finally run:

I tested this locally and then ran this on the production database. Obviously things did not go as planned but thankfully I had made database backups so I fixed those issues and was able to get the prod database fully migrated. Please backup your production database before you run any migrations on it.

You can read the change log of this feature and the UI images here in the official app change log:

Bookmark feature Updated - Open Past Paper

Bookmarking just got smarter — create multiple folders per subject and sort questions into custom groups like Solved, Unsolved, or Errors for easier organization.