fix: streaming export losing g context #36950

dpgaspar · 2026-01-07T11:55:26Z

SUMMARY

Streaming CSV exports create a new Flask app context when the generator runs, which causes flask.g attributes from the original request to be lost. This can break functionality that relies on request-scoped data stored in g.

This fix:

Captures all flask.g attributes when the command is initialized (during the original request context)
Restores them via preserve_g_context() when the generator executes in the new app context

BEFORE/AFTER SCREENSHOTS OR ANIMATED GIF

N/A - backend change

TESTING INSTRUCTIONS

Run existing tests: pytest tests/unit_tests/commands/sql_lab/streaming_export_command_test.py -v
All 16 tests should pass

ADDITIONAL INFORMATION

Has associated issue:
Required feature flags:
Changes UI
Includes DB Migration (follow approval process in SIP-59)
- Migration is atomic, supports rollback & is backwards-compatible
- Confirm DB migration upgrade and downgrade tested
- Runtime estimates and downtime expectations provided
Introduces new feature or API
Removes existing feature or API

codeant-ai-for-open-source · 2026-01-07T11:55:31Z

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codeant-ai-for-open-source · 2026-01-07T11:57:41Z

Nitpicks 🔍

🔒 No security issues identified
⚡ Recommended areas for review Context restore semantics `preserve_g_context` sets attributes on `g` and then deletes them in the finally block. If the target app context already had attributes with the same keys, they will be overwritten and then removed, potentially losing original values. The context manager should preserve and restore previous values (or avoid deleting pre-existing attributes). g capture method Capturing attributes via `dir(g)` and `getattr(g, key)` may pick up class attributes, descriptors, callables, or attributes that raise on access. This can cause unexpected behavior or exceptions during capture and may include non-instance data that should not be copied to the streaming context. Consider using the g instance dict (e.g. `g.__dict__`) or defensive access to only copy user-set attributes. Capture timing / staleness The code captures `g` attributes in `__init__`. If the command object is constructed outside the request/app context (or long before `run()` is called), the captured data may be empty or stale. Capture request-scoped state at the time `run()` is invoked (or immediately before starting the streaming generator).

netlify · 2026-01-07T11:58:45Z

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superset/commands/streaming_export/base.py

codeant-ai-for-open-source · 2026-01-07T12:00:04Z

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Code Review Agent Run #65a420

Actionable Suggestions - 1

superset/commands/streaming_export/base.py - 1
- Blind exception catch too broad · Line 240-240

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- superset/commands/streaming_export/base.py
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superset/commands/streaming_export/base.py

codecov · 2026-01-07T12:11:51Z

Codecov Report

❌ Patch coverage is 23.52941% with 13 lines in your changes missing coverage. Please review.
✅ Project coverage is 68.17%. Comparing base (2080633) to head (cf3d135).
⚠️ Report is 24 commits behind head on master.

Files with missing lines	Patch %	Lines
superset/commands/streaming_export/base.py	23.52%	13 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           master   #36950       +/-   ##
===========================================
+ Coverage        0   68.17%   +68.17%     
===========================================
  Files           0      639      +639     
  Lines           0    47665    +47665     
  Branches        0     5205     +5205     
===========================================
+ Hits            0    32494    +32494     
- Misses          0    13891    +13891     
- Partials        0     1280     +1280

Flag	Coverage Δ
hive	`43.09% <23.52%> (?)`
mysql	`66.17% <23.52%> (?)`
postgres	`66.22% <23.52%> (?)`
presto	`46.69% <23.52%> (?)`
python	`68.14% <23.52%> (?)`
sqlite	`65.94% <23.52%> (?)`
unit	`100.00% <ø> (?)`

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The app context is discarded after the generator finishes, so cleaning up g attributes is unnecessary. 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude Opus 4.5 <[email protected]>

Capture flask.g attributes right before creating the generator rather than at command construction time. This is closer to when we actually need the data and avoids holding onto g state longer than necessary. 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude Opus 4.5 <[email protected]>

bito-code-review · 2026-01-07T13:06:26Z

Code Review Agent Run #8fd3f4

Actionable Suggestions - 0

Review Details

Files reviewed - 1 · Commit Range: 37119f9..cf3d135
- superset/commands/streaming_export/base.py
Files skipped - 0
Tools
- Whispers (Secret Scanner) - ✔︎ Successful
- Detect-secrets (Secret Scanner) - ✔︎ Successful
- MyPy (Static Code Analysis) - ✔︎ Successful
- Astral Ruff (Static Code Analysis) - ✔︎ Successful

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amaannawab923

Thanks ! LGTM !

Co-authored-by: Claude Opus 4.5 <[email protected]>

fix: streaming export losing g context

37119f9

pull-request-size bot added the size/M label Jan 7, 2026

dosubot bot added the change:backend Requires changing the backend label Jan 7, 2026

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improve

3966ee9

dpgaspar and others added 2 commits January 7, 2026 12:17

chore: remove unnecessary cleanup in preserve_g_context

d33b0d5

The app context is discarded after the generator finishes, so cleaning up g attributes is unnecessary. 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude Opus 4.5 <[email protected]>

dpgaspar force-pushed the fix/upstream-streaming-export branch from 3d4cf23 to cf3d135 Compare January 7, 2026 12:20

dpgaspar requested a review from geido January 7, 2026 12:22

amaannawab923 approved these changes Jan 7, 2026

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dpgaspar merged commit a6d85dc into apache:master Jan 8, 2026
65 checks passed

dpgaspar deleted the fix/upstream-streaming-export branch January 8, 2026 16:11

sadpandajoe added the 6.0:checkpoint label Jan 8, 2026

JCelento pushed a commit to JCelento/superset that referenced this pull request Jan 8, 2026

fix: streaming export losing g context (apache#36950)

b865bcf

Co-authored-by: Claude Opus 4.5 <[email protected]>

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SUMMARY

BEFORE/AFTER SCREENSHOTS OR ANIMATED GIF

TESTING INSTRUCTIONS

ADDITIONAL INFORMATION

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