fix: pandas bug when data is blank on post-processing

[eschutho]

SUMMARY

There's a bug in post processing for tables and pivot-table charts when the data is empty for both json and csv formats. We'll now just return the original results instead of trying to apply any post-processing on it.

BEFORE/AFTER SCREENSHOTS OR ANIMATED GIF

Currently raises a 500

TESTING INSTRUCTIONS

Create a chart with no results for a pivot table and then try to export pivoted results as csv. This would also break on alert/reports when formatting the report as a csv.

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

[betodealmeida]

I think it would be better to continue here and in line 336, since other queries might have data (and if they also don't we'll end up returning result unmodified).

[john-bodley]

What is query["data"] in this case? Would it be preferable to first check whether query["data"] is valid? Per your unit tests it seems like this might be an empty string—the worst of the worst—and maybe we could/should fix this upstream and have it be None, i.e., the following works:

>>> import pandas as pd
>>> pd.DataFrame.from_dict(None)
Empty DataFrame
Columns: []
Index: []

[eschutho]

@betodealmeida if the data is None or '', is there any value in continuing this process rather than returning early? AFAICT we'll continue to get more errors down below as well. Per @john-bodley's point, I can do a nullish check instead of the try/except if we want to be more specific to these errors.

[betodealmeida]

If you continue here it would skip to the next step of the for query in result["queries"] loop, so it wouldn't get more errors. There could be other queries in result["queries"] that have non-blank data.

[eschutho]

Ok, I see what you're saying. I also added a new test for multiple queries.

[eschutho]

based on @john-bodley's comment, i added a few more tests when data is None and found a case where it errors later in the code, so I put a nullish check like he suggested instead of the try/except.

[codecov]

Codecov Report

Merging #20629 (5a632fd) into master (b39a3d8) will decrease coverage by 0.14%.
The diff coverage is 89.06%.

❗ Current head 5a632fd differs from pull request most recent head c701d6f. Consider uploading reports for the commit c701d6f to get more accurate results

@@            Coverage Diff             @@
##           master   #20629      +/-   ##
==========================================
- Coverage   66.82%   66.67%   -0.15%     
==========================================
  Files        1752     1752              
  Lines       65616    65570      -46     
  Branches     6938     6938              
==========================================
- Hits        43849    43722     -127     
- Misses      20007    20088      +81     
  Partials     1760     1760              

Flag	Coverage Δ
hive	?
mysql	82.45% <93.86%> (+0.07%)	⬆️
postgres	82.53% <93.86%> (+0.07%)	⬆️
presto	?
python	82.61% <93.86%> (-0.29%)	⬇️
sqlite	82.31% <93.86%> (+0.07%)	⬆️
unit	?

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
...ackages/superset-ui-core/src/utils/featureFlags.ts	100.00% <ø> (ø)
...frontend/plugins/plugin-chart-table/src/Styles.tsx	100.00% <ø> (ø)
...nd/plugins/plugin-chart-table/src/controlPanel.tsx	43.47% <ø> (ø)
...perset-frontend/src/addSlice/AddSliceContainer.tsx	66.66% <ø> (ø)
...frontend/src/components/DatabaseSelector/index.tsx	88.88% <ø> (ø)
...end/src/components/Datasource/DatasourceEditor.jsx	65.61% <ø> (ø)
...et-frontend/src/components/EditableTitle/index.tsx	64.28% <ø> (ø)
...frontend/src/components/ImportModal/ErrorAlert.tsx	33.33% <ø> (ø)
...src/dashboard/components/PropertiesModal/index.tsx	62.98% <ø> (ø)
...ersConfigModal/FiltersConfigForm/DatasetSelect.tsx	40.00% <ø> (ø)
... and 141 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update b39a3d8...c701d6f. Read the comment docs.

[betodealmeida]

Looks great!