Avoid extra DB operations

[sravfeyn]

Technical Summary

Implements high ROI items from https://github.com/dimagi/connect-id/pull/211/files

https://dimagi.atlassian.net/browse/CI-426

Logging and monitoring

Safety Assurance

Safety story

• I am confident that this change will not break current and/or previous versions of CommCare apps

Automated test coverage

Tests exists

QA Plan

NA

Labels & Review

• The set of people pinged as reviewers is appropriate for the level of risk of the change

[coderabbitai]

Walkthrough

This pull request introduces two database query optimizations to reduce N+1 query problems. In messaging/views.py, the Channel list view now uses select_related("server") to eagerly load related server data in a single joined query instead of lazy-loading server relationships per channel. In utils/notification.py, the user query is optimized with a Prefetch object that eagerly loads active FCMDevice objects and exposes them via a user.active_devices attribute, replacing the per-user device lookup pattern. Both changes maintain existing function signatures and behavior while improving database efficiency.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Pre-merge checks and finishing touches

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	You can run @coderabbitai generate docstrings to improve docstring coverage.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title 'Avoid extra DB operations' directly and clearly summarizes the main change: database query optimization to reduce unnecessary database hits in both messaging/views.py and utils/notification.py.
Description check	✅ Passed	The description is related to the changeset, referencing PR #211, Jira CI-426, and documenting safety assurance with test coverage confirmation, though it lacks detailed explanation of specific optimizations.

✨ Finishing touches

• 📝 Generate docstrings

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch sr/bulk

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📜 Recent review details

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between ace11e6 and 56ce0f1.

📒 Files selected for processing (2)

• messaging/views.py
• utils/notification.py

🧰 Additional context used

🧬 Code graph analysis (2)

utils/notification.py (2)

users/models.py (1)

• ConnectUser (30-118)

conftest.py (2)

• fcm_device (31-32)
• user (21-22)

messaging/views.py (2)

messaging/models.py (1)

• Channel (25-35)

conftest.py (1)

• user (21-22)

🔇 Additional comments (2)

utils/notification.py (1)

1-1: LGTM! Effective N+1 query optimization.

The prefetch optimization correctly eliminates per-user database queries for active FCM devices. The logic change from .filter(...).first() to accessing the prefetched user.active_devices[0] maintains identical behavior while reducing database round-trips.

Also applies to: 18-20, 30-30

messaging/views.py (1)

380-380: LGTM! Proper select_related optimization.

Using select_related("server") correctly eliminates N+1 queries when accessing channel.server.key_url in the loop at line 388. This ForeignKey optimization complements the prefetch pattern used elsewhere in the codebase.

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