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fix: avoid invalid CAST(NULL AS NULL) in SQLGlot compiler #17487

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Merged
shuoweil merged 3 commits into from
Jun 18, 2026
+14 −0
Merged

fix: avoid invalid CAST(NULL AS NULL) in SQLGlot compiler #17487

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b00ac3d
fix: avoid invalid CAST(NULL AS NULL) in SQLGlot compiler
shuoweil Jun 16, 2026
a423241
Update packages/bigframes/bigframes/core/compile/sqlglot/sql/base.py
shuoweil Jun 16, 2026
b0e4b6b
Merge branch 'main' into shuowei-fix-sqlglot-null-cast
shuoweil Jun 18, 2026
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2 changes: 2 additions & 0 deletions packages/bigframes/bigframes/core/compile/sqlglot/sql/base.py
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Original file line number Diff line number Diff line change
Expand Up @@ -69,6 +69,8 @@ def literal(value: typing.Any, dtype: dtypes.Dtype | None = None) -> sge.Express
return sge.Null()

if value is None:
if str(sqlglot_type).upper() == "NULL":
return sge.Null()
return cast(sge.Null(), sqlglot_type)
if dtypes.is_struct_like(dtype):
items = [
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12 changes: 12 additions & 0 deletions packages/bigframes/tests/unit/core/compile/sqlglot/sql/test_base.py
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Expand Up @@ -159,3 +159,15 @@ def test_literal_explicit_dtype(value, dtype, expected):
def test_literal_for_list(value: list, expected: str):
got = sql.to_sql(sql.literal(value))
assert got == expected


def test_literal_null_type():
import unittest.mock as mock

mock_dtype = mock.Mock()
with mock.patch(
"bigframes.core.compile.sqlglot.sql.base.sgt.from_bigframes_dtype",
return_value="NULL",
):
got = sql.to_sql(sql.literal(None, dtype=mock_dtype))
assert got == "NULL"
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