Fix patternProperties/propertyNames key constraints lost with field_constraints (#2994)

Author: koxudaxi

src/datamodel_code_generator/parser/jsonschema.py

@@ -2912,7 +2912,7 @@ def parse_pattern_properties(
                     is_dict=True,
                     dict_key=self.data_type_manager.get_data_type(
                         Types.string,
-                        pattern=merged_pattern if not self.field_constraints else None,
+                        pattern=merged_pattern,
                     ),
                 )
             )
@@ -2975,7 +2975,7 @@ def parse_property_names(  # noqa: PLR0912
             or property_names.maxLength is not None
         ):
             kwargs: dict[str, Any] = {}
-            if property_names.pattern and not self.field_constraints:
+            if property_names.pattern:
                 kwargs["pattern"] = property_names.pattern
             if property_names.minLength is not None:
                 kwargs["minLength"] = property_names.minLength

tests/data/expected/main/jsonschema/pattern_properties_field_constraints.py

@@ -4,12 +4,12 @@
 
 from __future__ import annotations
 
-from pydantic import BaseModel
+from pydantic import BaseModel, constr
 
 
 class Bar(BaseModel):
     name: str | None = None
 
 
 class Foo(BaseModel):
-    bar: dict[str, Bar]
+    bar: dict[constr(regex=r'^([a-zA-Z_][a-zA-Z0-9_]*)$'), Bar]

tests/data/expected/main/jsonschema/pattern_properties_use_annotated.py

@@ -0,0 +1,15 @@
+# generated by datamodel-codegen:
+#   filename:  pattern_properties.json
+#   timestamp: 2019-07-26T00:00:00+00:00
+
+from __future__ import annotations
+
+from pydantic import BaseModel, constr
+
+
+class Bar(BaseModel):
+    name: str | None = None
+
+
+class Foo(BaseModel):
+    bar: dict[constr(pattern=r'^([a-zA-Z_][a-zA-Z0-9_]*)$'), Bar]

tests/data/expected/main/jsonschema/property_names_pattern_field_constraints.py

@@ -0,0 +1,11 @@
+# generated by datamodel-codegen:
+#   filename:  property_names_pattern.json
+#   timestamp: 2019-07-26T00:00:00+00:00
+
+from __future__ import annotations
+
+from pydantic import Field, RootModel, constr
+
+
+class PatternKeys(RootModel[dict[constr(pattern=r'^[a-z]+$'), str]]):
+    root: dict[constr(pattern=r'^[a-z]+$'), str] = Field(..., title='PatternKeys')

tests/main/jsonschema/test_main_jsonschema.py

@@ -3083,6 +3083,18 @@ def test_jsonschema_pattern_properties_field_constraints(output_file: Path) -> N
     )
 
 
+def test_jsonschema_pattern_properties_use_annotated(output_file: Path) -> None:
+    """Test pattern properties with --use-annotated preserves pattern constraint on dict keys."""
+    run_main_and_assert(
+        input_path=JSON_SCHEMA_DATA_PATH / "pattern_properties.json",
+        output_path=output_file,
+        input_file_type="jsonschema",
+        assert_func=assert_file_content,
+        expected_file="pattern_properties_use_annotated.py",
+        extra_args=["--output-model-type", "pydantic_v2.BaseModel", "--use-annotated"],
+    )
+
+
 @LEGACY_BLACK_SKIP
 def test_jsonschema_titles(output_file: Path) -> None:
     """Test JSON Schema title handling."""
@@ -3892,6 +3904,22 @@ def test_main_jsonschema_property_names_pattern(output_file: Path) -> None:
     )
 
 
+def test_main_jsonschema_property_names_pattern_field_constraints(output_file: Path) -> None:
+    """Test propertyNames pattern with field_constraints preserves constr key."""
+    run_main_and_assert(
+        input_path=JSON_SCHEMA_DATA_PATH / "property_names_pattern.json",
+        output_path=output_file,
+        input_file_type="jsonschema",
+        assert_func=assert_file_content,
+        expected_file="property_names_pattern_field_constraints.py",
+        extra_args=[
+            "--output-model-type",
+            "pydantic_v2.BaseModel",
+            "--field-constraints",
+        ],
+    )
+
+
 def test_main_jsonschema_property_names_enum(output_file: Path) -> None:
     """Test propertyNames with enum constraint generates dict with Literal key."""
     run_main_and_assert(