Resolving FastAPI and Strawberry GraphQL Dependency Issues: A Clear Solution

Struggling with FastAPI and Strawberry GraphQL context dependencies? Discover how to properly set up your dependencies for seamless integration and functionality in your application.
---
This video is based on the question https://stackoverflow.com/q/72584392/ asked by the user 'MWood' ( https://stackoverflow.com/u/1278889/ ) and on the answer https://stackoverflow.com/a/72586616/ provided by the user 'M.O.' ( https://stackoverflow.com/u/11612918/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: Problem combining FastAPI dependency and Strawberry GraphQL context

Also, Content (except music) licensed under CC BY-SA https://meta.stackexchange.com/help/l...
The original Question post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license.

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
Introduction

In modern web applications, using asynchronous frameworks like FastAPI alongside GraphQL solutions like Strawberry can boost efficiency and scalability. However, developers often encounter challenges when it comes to integrating these technologies, especially regarding dependency injection and context management. One common issue is ensuring that your dependencies are called correctly within context functions in GraphQL routes.

In this guide, we will tackle a specific problem many developers face: how to correctly combine FastAPI dependency injection with Strawberry GraphQL context. We will break down the problem and provide a clear solution that you can implement in your applications.

The Problem

Suppose you have a FastAPI application that uses both standard HTTP routes and GraphQL routes. When you attempt to create a context for your GraphQL API using a dependency that provides user information, you may notice that the dependency isn’t being invoked correctly. In particular:

You have a method that works perfectly for standard routes using FastAPI's Depends, but when you try to implement a similar functionality in your GraphQL context, the dependency does not return the expected user information.

Instead, you may see unexpected output like <inspect._empty object at ...> in your logs, indicating that the dependency isn't being executed as intended.

The Solution

The solution to this dependency issue revolves around correctly passing your dependency into the Depends function when defining your GraphQL context. Let's break this down step-by-step.

Step 1: Understand Your Current Implementation

Here’s how you might be defining your FastAPI routes:

[[See Video to Reveal this Text or Code Snippet]]

This implementation works as get_current_user is invoked correctly as a dependency.

However, in your GraphQL context definition, you might have something like this:

[[See Video to Reveal this Text or Code Snippet]]

In the above code, the issue arises due to invoking get_current_user() instead of passing the function reference as is done in the HTTP route (Depends(get_current_user) without parentheses).

Step 2: Modify the GraphQL Context

To fix this, you need to update your get_context function declaration to correctly handle the dependency. Modify it to the following:

[[See Video to Reveal this Text or Code Snippet]]

Step 3: Verifying the Implementation

After making the change, you can now create your GraphQL router like this:

[[See Video to Reveal this Text or Code Snippet]]

Step 4: Testing the Functionality

Once finalized, test your GraphQL API to ensure that get_current_user is called appropriately. Instead of receiving <inspect._empty object at ...>, you should now see the actual user information in your logs and the intended functionality in your application.

Conclusion

In summary, the integration between FastAPI and Strawberry GraphQL can be straightforward when you understand how dependency injection works in both contexts. By ensuring that you pass function references without invoking them directly, you can set up a reliable context for your GraphQL API.

If you follow the steps outlined above, you should resolve any issues related to dependency handling in your application’s GraphQL routes. Happy coding!