Fix field name shadowing in Pydantic models and add corresponding tests (#2657)

Author: koxudaxi

src/datamodel_code_generator/parser/base.py

@@ -1640,7 +1640,7 @@ def __change_field_name(
         self,
         models: list[DataModel],
     ) -> None:
-        if self.data_model_type != pydantic_model_v2.BaseModel:
+        if not issubclass(self.data_model_type, pydantic_model_v2.BaseModel):
             return
         for model in models:
             if "Enum" in model.base_class:

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

@@ -0,0 +1,17 @@
+# generated by datamodel-codegen:
+#   filename:  field_name_shadows_class_name.json
+#   timestamp: 2019-07-26T00:00:00+00:00
+
+from __future__ import annotations
+
+from typing import List, Optional
+
+from pydantic import BaseModel, Field
+
+
+class Elem(BaseModel):
+    temp: str
+
+
+class Model(BaseModel):
+    Elem_1: Optional[List[Elem]] = Field(None, alias='Elem')

tests/data/jsonschema/field_name_shadows_class_name.json

@@ -0,0 +1,30 @@
+{
+  "$schema": "http://json-schema.org/draft-07/schema#",
+  "definitions": {
+    "Elem": {
+      "type": "object",
+      "properties": {
+        "temp": {
+          "type": "string"
+        }
+      },
+      "required": ["temp"]
+    }
+  },
+  "type": "object",
+  "properties": {
+    "Elem": {
+      "anyOf": [
+        {
+          "type": "array",
+          "items": {
+            "$ref": "#/definitions/Elem"
+          }
+        },
+        {
+          "type": "null"
+        }
+      ]
+    }
+  }
+}

tests/main/jsonschema/test_main_jsonschema.py

@@ -3775,3 +3775,18 @@ def test_main_use_frozen_field_dataclass(output_file: Path) -> None:
             "--use-frozen-field",
         ],
     )
+
+
+@pytest.mark.benchmark
+def test_main_field_name_shadows_class_name(output_file: Path) -> None:
+    """Test field name shadowing class name is renamed with alias for Pydantic v2."""
+    run_main_and_assert(
+        input_path=JSON_SCHEMA_DATA_PATH / "field_name_shadows_class_name.json",
+        output_path=output_file,
+        input_file_type="jsonschema",
+        assert_func=assert_file_content,
+        extra_args=[
+            "--output-model-type",
+            "pydantic_v2.BaseModel",
+        ],
+    )