add latest aggregate forecast json to question object by lsabor · Pull Request #4908 · Metaculus/metaculus

lsabor · 2026-06-18T15:29:58Z

addresses the main push of #4907

Summary by CodeRabbit

New Features
- Added a new field on questions to store the latest aggregate forecast snapshot.
Changes
- Backfilled the field for currently open questions with their most recent aggregate forecast.
- Updated forecast building to keep the field in sync with the latest available aggregate forecast prior to the current time.

coderabbitai · 2026-06-18T15:30:15Z

No actionable comments were generated in the recent review. 🎉

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📥 Commits

Reviewing files that changed from the base of the PR and between 80bc458 and 48080be.

📒 Files selected for processing (1)

questions/services/forecasts.py

🚧 Files skipped from review as they are similar to previous changes (1)

questions/services/forecasts.py

📝 Walkthrough

Walkthrough

Adds a latest_aggregate_forecast nullable JSONField to the Question model. A data migration backfills the field for currently open questions by serializing the most recent AggregateForecast row. The build_question_forecasts service function is updated to maintain this field at runtime using bisect_left on aggregation_history.

Changes

Latest Aggregate Forecast Cache

Layer / File(s)	Summary
Model field definition and data migration `questions/models.py`, `questions/migrations/0038_question_latest_aggregate_forecast.py`	Adds `latest_aggregate_forecast` as a nullable/blank `JSONField` on `Question`. The migration adds the column and backfills it for open questions (no `actual_close_time`, `open_time__lte=now`) by fetching the latest `aggregate_forecasts` row by `start_time` and serializing it with `serialize_aggregate_forecast(..., full=True)`. Reverse operation is a no-op.
Runtime update in `build_question_forecasts` `questions/services/forecasts.py`	Imports `bisect_left` and `serialize_aggregate_forecast`. After bulk-creating/updating `AggregateForecast` rows, uses `bisect_left` on `start_time` in `aggregation_history` to find the most recent aggregate before `timezone.now()` and assigns the full serialized form to `question.latest_aggregate_forecast`.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Poem

🐇 A field so fresh, it gleams with JSON light,
The latest forecast cached, no need to search tonight.
Migration hops along, backfilling every row,
bisect_left finds the time—the rabbit's on the go!
The question knows its forecast, stored neat and tight. ✨

🚥 Pre-merge checks | ✅ 4

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately summarizes the main change: adding a new JSONField for the latest aggregate forecast to the Question model, which is the primary objective of the pull request.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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✨ Finishing Touches

📝 Generate docstrings

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Commit on current branch

🧪 Generate unit tests (beta)

Create PR with unit tests
Commit unit tests in branch issue/4907/latest-agg-json-on-question

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Actionable comments posted: 2

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@questions/migrations/0038_question_latest_aggregate_forecast.py`:
- Line 6: Remove the import of serialize_aggregate_forecast from
questions.serializers.aggregate_forecasts at the top of the migration file.
Instead, copy the serialization logic directly into the migration file or
implement the serialization logic inline without relying on external application
code. Update any calls to serialize_aggregate_forecast within the migration to
use the local implementation instead. This ensures the migration is
self-contained and will not break if the external serializer changes in the
future.

In `@questions/services/forecasts.py`:
- Around line 584-591: The code only updates question.latest_aggregate_forecast
when latest_index > 0, but when no eligible aggregate exists (latest_index
equals 0 or less), the previous cached value is never cleared and remains stale.
Add an else clause after the if latest_index > 0 condition that sets
question.latest_aggregate_forecast to None to explicitly clear the cache when no
prior aggregate exists.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

Push a commit to this branch (recommended)
Create a new PR with the fixes

ℹ️ Review info

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Configuration used: Path: .coderabbit.yaml

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📥 Commits

Reviewing files that changed from the base of the PR and between 23ee8aa and 80bc458.

📒 Files selected for processing (3)

questions/migrations/0038_question_latest_aggregate_forecast.py
questions/models.py
questions/services/forecasts.py

coderabbitai · 2026-06-18T15:34:45Z

+from django.db import migrations, models
+from django.utils import timezone
+
+from questions.serializers.aggregate_forecasts import serialize_aggregate_forecast


⚠️ Potential issue | 🟠 Major | ⚡ Quick win

Avoid runtime serializer imports inside migrations.

On Line 6, importing questions.serializers.aggregate_forecasts.serialize_aggregate_forecast makes this migration depend on mutable application code. If that serializer changes later, migration replay can fail on clean installs. Keep serialization logic snapshot-local inside this migration (or serialize from historical model fields directly).

🤖 Prompt for AI Agents

Verify each finding against current code. Fix only still-valid issues, skip the rest with a brief reason, keep changes minimal, and validate. In `@questions/migrations/0038_question_latest_aggregate_forecast.py` at line 6, Remove the import of serialize_aggregate_forecast from questions.serializers.aggregate_forecasts at the top of the migration file. Instead, copy the serialization logic directly into the migration file or implement the serialization logic inline without relying on external application code. Update any calls to serialize_aggregate_forecast within the migration to use the local implementation instead. This ensures the migration is self-contained and will not break if the external serializer changes in the future.

github-actions · 2026-06-18T15:45:11Z

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add latest aggregate forecast json to question object

80bc458

lsabor requested a review from hlbmtc June 18, 2026 15:30

lsabor had a problem deploying to testing_env June 18, 2026 15:30 — with GitHub Actions Error

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48080be

lsabor temporarily deployed to testing_env June 18, 2026 15:32 — with GitHub Actions Inactive

coderabbitai Bot reviewed Jun 18, 2026

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add latest aggregate forecast json to question object#4908

add latest aggregate forecast json to question object#4908
lsabor wants to merge 2 commits into
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issue/4907/latest-agg-json-on-question

lsabor commented Jun 18, 2026 •

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lsabor commented Jun 18, 2026 •

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