bugfix: Oracle timegrains fail to render when wrapped in outer query

[villebro]

CATEGORY

• Bug Fix

SUMMARY

This bug is slightly related to #7729 , where Oracle is forced to wrap an additional query around the original query. This causes the SQLAlchemy compiler to create a new column object based on the original TimestampExpression, which doesn't receive a column (is only supposed to have the label of the original object), and hence is unable to complete the compilation. This is solved by passing a ColumnClause class to the method via the _constructor property that creates the outer query proxy column, which solves the problem.

Before

After

TEST PLAN

Tested locally to work on sqlite (regression testing) and Oracle, with and without time grain.

ADDITIONAL INFORMATION

• Has associated issue: Fixes When connecting to the oracle database, an error is reported when making a line chart #7765

REVIEWERS

@devilzhangzzz

[villebro]

Oracle seems to be pushing me ever deeper into this rabbit hole of proxied label elements.. Hope this is the last of this. This is now ready for review @devilzhangzzz @mistercrunch @john-bodley

[codecov-io]

Codecov Report

Merging #7767 into master will decrease coverage by 0.14%.
The diff coverage is 50%.

@@            Coverage Diff             @@
##           master    #7767      +/-   ##
==========================================
- Coverage   65.71%   65.56%   -0.15%     
==========================================
  Files         459      459              
  Lines       21981    21983       +2     
  Branches     2415     2415              
==========================================
- Hits        14445    14414      -31     
- Misses       7415     7448      +33     
  Partials      121      121

Impacted Files	Coverage Δ
superset/db_engine_specs/base.py	87.98% <50%> (-0.33%)	⬇️
superset/db_engine_specs/mysql.py	34.88% <0%> (-58.14%)	⬇️
superset/models/core.py	83.02% <0%> (-0.62%)	⬇️
superset/views/core.py	72.87% <0%> (-0.21%)	⬇️

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