Solving the Challenge of HTML Form Image Submission to FastAPI via Django

Discover the solution to the common issue of sending images from a Django form to a FastAPI endpoint. Dive into our comprehensive breakdown and troubleshooting tips!
---
This video is based on the question https://stackoverflow.com/q/67096698/ asked by the user 'Slobjo' ( https://stackoverflow.com/u/14501781/ ) and on the answer https://stackoverflow.com/a/67096919/ provided by the user 'Slobjo' ( https://stackoverflow.com/u/14501781/ ) 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: HTML form doesn't want to send an image

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.
---
How to Successfully Send Images from HTML Forms to FastAPI via Django

When you're working with complex web applications, particularly those that involve multiple frameworks, issues can arise that may be difficult to troubleshoot. For instance, have you ever encountered a scenario where your HTML form fails to submit an image to a FastAPI service, even though you're confident that your implementation is correct? If so, you're not alone! In this guide, we'll explore a specific case where a Django server needed to send image files to a FastAPI service, and how a subtle mistake caused the process to fail.

The Problem: Image Submission Fails

In our scenario, we have a Django application that interacts with an OCR service built using FastAPI. The critical aspect of this interaction is image handling, as the OCR service processes images received from the Django server. However, when attempting to send images, the request doesn't seem to carry the image data to FastAPI correctly. The issues manifested like this:

Image Submission: The Django form includes an input for image upload.

Successful Submission via Swagger UI: When tested via Swagger UI, it works flawlessly, indicating the FastAPI side is set up correctly.

Django Form Issues: When submitting through the Django application, the FastAPI service fails to receive the image part of the request.

A Look at the Code

FastAPI Endpoint

The relevant portion of the FastAPI code is as follows:

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

This indicates that FastAPI is expecting an image file to be sent properly in a multipart/form-data format.

Django Form

The Django form used for image upload looks like this:

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

Django View Implementation

In the Django view, the code for handling the form submission reads as follows:

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

Here, the program reads the uploaded file, opens it, and tries to send it to the FastAPI endpoint.

The Solution: Key Changes Needed

After spending countless hours troubleshooting the issue, the resolution turned out to be deceptively simple!

The code snippet where the image file was prepared for sending required a key adjustment.

Here's the Fix:

In the Django view, change the dictionary key used in the files argument of the requests.post method:

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

Instead of using 'file', which was incorrect, changing it to 'image' aligned with the key expected by the FastAPI endpoint.

Implementation Summary

Before:

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

After:

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

Conclusion

By making this minor adjustment, the FastAPI service successfully receives the image file, and full functionality is restored. This calls attention to the importance of consistently aligning the keys used in requests with the expected inputs defined on the receiving end.

Wrapping Up

In conclusion, while building applications using multiple frameworks can cause confusion and issues, a careful review of how data is sent and expected can resolve most problems. Remember to double-check your keys and ensure they match on both sides (the sender and receiver) for smooth communication between services. Happy coding!