fix(dashboard): 500 error caused by data_for_slices API

[ktmud]

SUMMARY

Fix a 500 error on the /dashboard/<dashboardId>/datasets API caused by an incorrect nested list comprehension introduced by #15993 .

Traceback (most recent call last):
  File "/usr/local/lib/python3.8/dist-packages/flask_appbuilder/api/__init__.py", line 85, in wraps
    return f(self, *args, **kwargs)
  File "superset/views/base_api.py", line 85, in wraps
    raise ex
  File "superset/views/base_api.py", line 82, in wraps
    duration, response = time_function(f, self, *args, **kwargs)
  File "superset/utils/core.py", line 1367, in time_function
    response = func(*args, **kwargs)
  File "superset/utils/log.py", line 241, in wrapper
    value = f(*args, **kwargs)
  File "superset/dashboards/api.py", line 334, in get_datasets
    datasets = DashboardDAO.get_datasets_for_dashboard(id_or_slug)
  File "superset/dashboards/dao.py", line 52, in get_datasets_for_dashboard
    return dashboard.datasets_trimmed_for_slices()
  File "/usr/local/lib/python3.8/dist-packages/flask_caching/__init__.py", line 905, in decorated_function
    return f(*args, **kwargs)
  File "superset/models/dashboard.py", line 280, in datasets_trimmed_for_slices
    result.append(datasource.data_for_slices(slices))
  File "superset/connectors/base/models.py", line 309, in data_for_slices
    column_names.update(
TypeError: unhashable type: 'dict'

Updated the test case to cover this case.

In dashboards where a slice has the y metric set (e.g. a NVD3 timeseries chart), the /datasets API will return 500. However, most of the time if will not break the dashboard, since this API is almost only used in FilterBox and filter indicators.

BEFORE/AFTER SCREENSHOTS OR ANIMATED GIF

N/A

TESTING INSTRUCTIONS

1. Test adding a NVD3 Timeseries chart to the dashboard
2. You may see 500 error in base but not error after the fix

ADDITIONAL INFORMATION

• Has associated issue:
• 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

[ktmud]

The order of the for loop is incorrect. Normally it will throw an undefined variable error but since param was used in other loops above, the code will still run. Just another example of why too many local variables is not a good thing.

[ktmud]

Bycatch refactor. No real code logic changes.

[codecov]

Codecov Report

Merging #16053 (3839452) into master (69c5cd7) will decrease coverage by 0.14%.
The diff coverage is 100.00%.

❗ Current head 3839452 differs from pull request most recent head f0fd52c. Consider uploading reports for the commit f0fd52c to get more accurate results

@@            Coverage Diff             @@
##           master   #16053      +/-   ##
==========================================
- Coverage   76.81%   76.66%   -0.15%     
==========================================
  Files         995      995              
  Lines       52869    52864       -5     
  Branches     6712     6712              
==========================================
- Hits        40610    40528      -82     
- Misses      12033    12110      +77     
  Partials      226      226              

Flag	Coverage Δ
hive	?
mysql	81.59% <100.00%> (-0.01%)	⬇️
postgres	81.62% <100.00%> (+0.03%)	⬆️
python	81.71% <100.00%> (-0.29%)	⬇️
sqlite	81.22% <100.00%> (-0.01%)	⬇️

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

Impacted Files	Coverage Δ
superset/viz.py	56.57% <ø> (ø)
superset/connectors/base/models.py	88.06% <100.00%> (ø)
superset/utils/core.py	88.09% <100.00%> (-0.21%)	⬇️
superset/db_engines/hive.py	0.00% <0.00%> (-82.15%)	⬇️
superset/db_engine_specs/hive.py	69.80% <0.00%> (-16.87%)	⬇️
superset/views/database/mixins.py	81.03% <0.00%> (-1.73%)	⬇️
superset/db_engine_specs/presto.py	83.47% <0.00%> (-1.05%)	⬇️
superset/db_engine_specs/base.py	87.98% <0.00%> (-0.39%)	⬇️
superset/connectors/sqla/models.py	88.08% <0.00%> (-0.24%)	⬇️

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[graceguo-supercat]

LGTM!

Thanks for quick fix!