Fix(parser): cast coalesce arg to text in the context of a CONCAT call

sqlglot/dialects/clickhouse.py

@@ -345,7 +345,7 @@ def safeconcat_sql(self, expression: exp.SafeConcat) -> str:
                 "CONCAT",
                 *[
                     exp.func("if", e.is_(exp.null()), e, exp.cast(e, "text"))
-                    for e in expression.expressions
+                    for e in t.cast(t.List[exp.Condition], expression.expressions)
                 ],
             )
 

sqlglot/expressions.py

@@ -3221,15 +3221,15 @@ def output_name(self) -> str:
         return self.name
 
 
-class Parameter(Expression):
+class Parameter(Condition):
     arg_types = {"this": True, "wrapped": False}
 
 
-class SessionParameter(Expression):
+class SessionParameter(Condition):
     arg_types = {"this": True, "kind": False}
 
 
-class Placeholder(Expression):
+class Placeholder(Condition):
     arg_types = {"this": False, "kind": False}
 
 

sqlglot/parser.py

@@ -3655,7 +3655,11 @@ def _parse_cast(self, strict: bool) -> exp.Expression:
     def _parse_concat(self) -> t.Optional[exp.Expression]:
         args = self._parse_csv(self._parse_conjunction)
         if self.CONCAT_NULL_OUTPUTS_STRING:
-            args = [exp.func("COALESCE", arg, exp.Literal.string("")) for arg in args]
+            args = [
+                exp.func("COALESCE", exp.cast(arg, "text"), exp.Literal.string(""))
+                for arg in args
+                if arg
+            ]
 
         # Some dialects (e.g. Trino) don't allow a single-argument CONCAT call, so when
         # we find such a call we replace it with its argument.

tests/dialects/test_clickhouse.py

@@ -53,7 +53,7 @@ def test_clickhouse(self):
         )
 
         self.validate_all(
-            "CONCAT(CASE WHEN COALESCE(a, '') IS NULL THEN COALESCE(a, '') ELSE CAST(COALESCE(a, '') AS TEXT) END, CASE WHEN COALESCE(b, '') IS NULL THEN COALESCE(b, '') ELSE CAST(COALESCE(b, '') AS TEXT) END)",
+            "CONCAT(CASE WHEN COALESCE(CAST(a AS TEXT), '') IS NULL THEN COALESCE(CAST(a AS TEXT), '') ELSE CAST(COALESCE(CAST(a AS TEXT), '') AS TEXT) END, CASE WHEN COALESCE(CAST(b AS TEXT), '') IS NULL THEN COALESCE(CAST(b AS TEXT), '') ELSE CAST(COALESCE(CAST(b AS TEXT), '') AS TEXT) END)",
             read={"postgres": "CONCAT(a, b)"},
         )
         self.validate_all(

tests/dialects/test_dialect.py

@@ -1192,7 +1192,7 @@ def test_operators(self):
             },
         )
         self.validate_all(
-            "COALESCE(a, '')",
+            "COALESCE(CAST(a AS TEXT), '')",
             read={
                 "drill": "CONCAT(a)",
                 "duckdb": "CONCAT(a)",

tests/dialects/test_postgres.py

@@ -577,13 +577,19 @@ def test_bool_or(self):
         )
 
     def test_string_concat(self):
+        self.validate_all(
+            "SELECT CONCAT('abcde', 2, NULL, 22)",
+            write={
+                "postgres": "SELECT CONCAT(COALESCE(CAST('abcde' AS TEXT), ''), COALESCE(CAST(2 AS TEXT), ''), COALESCE(CAST(NULL AS TEXT), ''), COALESCE(CAST(22 AS TEXT), ''))",
+            },
+        )
         self.validate_all(
             "CONCAT(a, b)",
             write={
-                "": "CONCAT(COALESCE(a, ''), COALESCE(b, ''))",
-                "duckdb": "CONCAT(COALESCE(a, ''), COALESCE(b, ''))",
-                "postgres": "CONCAT(COALESCE(a, ''), COALESCE(b, ''))",
-                "presto": "CONCAT(CAST(COALESCE(a, '') AS VARCHAR), CAST(COALESCE(b, '') AS VARCHAR))",
+                "": "CONCAT(COALESCE(CAST(a AS TEXT), ''), COALESCE(CAST(b AS TEXT), ''))",
+                "duckdb": "CONCAT(COALESCE(CAST(a AS TEXT), ''), COALESCE(CAST(b AS TEXT), ''))",
+                "postgres": "CONCAT(COALESCE(CAST(a AS TEXT), ''), COALESCE(CAST(b AS TEXT), ''))",
+                "presto": "CONCAT(CAST(COALESCE(CAST(a AS VARCHAR), '') AS VARCHAR), CAST(COALESCE(CAST(b AS VARCHAR), '') AS VARCHAR))",
             },
         )
         self.validate_all(