Service-Repository Pattern Implementation In Django For Your APIs

Imagine that you have a Django app with a views.py file, And you put all the logics of your APIs from database stuff to email sending and …

The problem with such a code is that at some point of time this file gets too large and there are a lot of unrelated logics in it.

The problems with this type of code includes:

• All Data Access and Business logics and all other logics are mixed together, And you don't know where to find some specific logic and updating your code will be hard.
• Your code is not testable or at least hard to test, Because a lot of logics are in a simple method or class or whatever …
• Your code is not reusable. Imagine you want to update a user's detail in a specific situation. You should probably duplicate your code when you want to update the user's detail in another situation when that specific condition happens.
• You can't scale your code. When some logics gets heavy you should scale your code and because your code is a mess you can't do it, Specially in microservices.
• You can't change your code easily.

To address these problems there is a design pattern that separates the logic and it's called "Service Repository Pattern".

Let's see an example of it in an API in Django.

Step 1: Create a services directory in your Django app with __init__.py file.

Step 2: Create a file named "user_service.py":

Step 3: Create a directory called "repositories" in your Django app and then create two files with the names "__init__.py" and "user_repository.py" in it.

Step 4: Create your Data Access login in your repository file.

You can see that we put database logic to get a user from database or creating a user in this file. This is a simple example, Imagine when you have a longer database logic.

Step 5: Create your service layer in "user_service.py" file.

Step 6: Create you views logic:

And that's it, You can use this pattern to have a more readable and testable code.

Hope you've enjoyed it.

Thanks for reading.

Updated : 12-12-2023

Note: This is a simple implementation of the pattern, and it does not have a robust dependency injection as I didn't completely implemented the constructor injection but wanted to show you a grasp of it.