Refactor/toggle-favourite endpoint to eliminate full-table query and improve query efficiency

[Riddhi8077]

Describe the feature

Overview

The current implementation of the /toggle-favourite endpoint retrieves all images from the database after updating the isFavourite flag, and then filters the target image in memory.

Although functionally correct, this introduces unnecessary database and processing overhead.

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Current Implementation

After toggling the favourite status, the route executes:

image = next(
    (img for img in db_get_all_images() if img["id"] == image_id), None
)

db_get_all_images() performs:

• Multiple JOIN operations
• Metadata parsing
• Tag grouping
• Dataset sorting

This entire workflow runs even though only a single image record is required.

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Why This Matters

This approach:

• Scales linearly with total image count
• Increases latency for a frequently used endpoint
• Performs unnecessary joins and metadata parsing
• Couples a single-record use case with a full-collection query

As image collections grow, this can negatively impact responsiveness.

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Proposed Improvement

1. Introduce a dedicated method:

   db_get_image_by_id(image_id: str)

2. Query only the required record with necessary JOINs.

3. Refactor /toggle-favourite to use this optimized method instead of calling db_get_all_images().

---

Expected Benefits

• Reduced database load
• Improved scalability
• Cleaner endpoint behavior
• Better separation of concerns

I would be happy to implement this improvement.

Record

• I agree to follow this project's Code of Conduct
• I want to work on this issue

[github-actions]

👋 Thanks for opening this issue! The maintainers will review it shortly. Till then, do not open any PR. This is a strict rule we like to follow around here :)

[Riddhi8077]

I would like to work on this improvement and have already started implementing the proposed refactor.

If there are no objections, I will proceed with introducing db_get_image_by_id and updating the /toggle-favourite endpoint accordingly. I will open a PR shortly.

Please let me know if you would prefer any changes to the approach.