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fix: parse column from cast expression for ScdType2 models #5475

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toriwei merged 2 commits into from
Oct 3, 2025
Merged

fix: parse column from cast expression for ScdType2 models #5475

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parse column from cast expression
toriwei Oct 2, 2025
a36a913
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toriwei Oct 2, 2025
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16 changes: 16 additions & 0 deletions sqlmesh/dbt/model.py
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Original file line number Diff line number Diff line change
Expand Up @@ -172,6 +172,22 @@ def _validate_check_cols(cls, v: t.Union[str, t.List[str]]) -> t.Union[str, t.Li
return "*"
return ensure_list(v)

@field_validator("updated_at", mode="before")
@classmethod
def _validate_updated_at(cls, v: t.Optional[str]) -> t.Optional[str]:
"""
Extract column name if updated_at contains a cast.

SCDType2ByTimeKind and SCDType2ByColumnKind expect a column, and the casting is done later.
"""
if v is None:
return None
parsed = d.parse_one(v)
if isinstance(parsed, exp.Cast) and isinstance(parsed.this, exp.Column):
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@eakmanrq eakmanrq Oct 2, 2025

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Can you add a comment explaining that both scd type 2 expects a column and the logic for it does a cast anyways so this shouldn't be needed? Could be an issue later so it would at least explaining the reasoning at this time.

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@toriwei toriwei Oct 2, 2025 •
edited
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updated with:


        """
        Extract column name if updated_at contains a cast.

        SCDType2ByTimeKind and SCDType2ByColumnKind expect a column, and the casting is done later.
        """

return parsed.this.name

return v

@field_validator("sql", mode="before")
@classmethod
def _validate_sql(cls, v: t.Union[str, SqlStr]) -> SqlStr:
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17 changes: 17 additions & 0 deletions tests/dbt/test_transformation.py
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Original file line number Diff line number Diff line change
Expand Up @@ -652,6 +652,23 @@ def test_model_kind():
== ManagedKind()
)

assert ModelConfig(
materialized=Materialization.SNAPSHOT,
unique_key=["id"],
updated_at="updated_at::timestamp",
strategy="timestamp",
dialect="redshift",
).model_kind(context) == SCDType2ByTimeKind(
unique_key=["id"],
valid_from_name="dbt_valid_from",
valid_to_name="dbt_valid_to",
updated_at_as_valid_from=True,
updated_at_name="updated_at",
dialect="redshift",
on_destructive_change=OnDestructiveChange.IGNORE,
on_additive_change=OnAdditiveChange.ALLOW,
)


def test_model_kind_snapshot_bigquery():
context = DbtContext()
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