fix(model): keep quoting when normalizing column_descriptions keys

_column_descriptions_validator built each key with part.this, which is the
bare identifier string, so the quoted flag was gone before
normalize_identifiers ran. A quoted key was then normalized as if it were
unquoted, and on dialects where quoting makes a column case-sensitive the
resulting name matched no column, so the description was dropped along with
the rest of the table's comments.

Normalize each part while it is still an identifier. Unquoted keys normalize
exactly as before.

Fixes #5943

Signed-off-by: ReguiguiMohamed <mohamedreguigui2004@gmail.com>

Author: ReguiguiMohamed

sqlmesh/core/model/meta.py

@@ -321,17 +321,19 @@ def _column_descriptions_validator(
         if isinstance(vs, (exp.Tuple, exp.Array)):
             vs = vs.expressions
 
-        raw_col_descriptions = (
-            vs
+        # Normalize each part while it is still an identifier, so that a quoted
+        # column keeps its case on dialects where quoting makes it significant.
+        col_descriptions = (
+            {normalize_identifiers(k, dialect=dialect).name: v for k, v in vs.items()}
             if isinstance(vs, dict)
-            else {".".join([part.this for part in v.this.parts]): v.expression.name for v in vs}
+            else {
+                ".".join(
+                    normalize_identifiers(part, dialect=dialect).name for part in v.this.parts
+                ): v.expression.name
+                for v in vs
+            }
         )
 
-        col_descriptions = {
-            normalize_identifiers(k, dialect=dialect).name: v
-            for k, v in raw_col_descriptions.items()
-        }
-
         columns_to_types = data.get("columns_to_types_")
         if columns_to_types:
             from sqlmesh.core.console import get_console

tests/core/test_model.py

@@ -1000,6 +1000,32 @@ def test_column_descriptions(sushi_context, assert_exp_eq):
     assert model.column_descriptions == {"id": "primary key", "foo": "bar"}
 
 
+def test_column_descriptions_quoted_identifier():
+    expressions = d.parse(
+        """
+        MODEL (
+            name db.table,
+            kind FULL,
+            dialect snowflake,
+            column_descriptions (
+                "myColumn" = 'a case-sensitive column',
+                other_column = 'an unquoted column'
+            )
+        );
+
+        SELECT 1 AS "myColumn", 2 AS other_column
+    """
+    )
+    model = load_sql_based_model(expressions, dialect="snowflake")
+
+    # A quoted key keeps its case, an unquoted one is still normalized.
+    assert model.column_descriptions == {
+        "myColumn": "a case-sensitive column",
+        "OTHER_COLUMN": "an unquoted column",
+    }
+    assert set(model.column_descriptions) <= set(model.columns_to_types)
+
+
 def test_model_jinja_macro_reference_extraction():
     @macro()
     def test_macro(**kwargs) -> None: