add exclude-typename-field

src/datamodel_code_generator/__init__.py

@@ -290,6 +290,7 @@ def generate(  # noqa: PLR0912, PLR0913, PLR0914, PLR0915
     no_alias: bool = False,
     formatters: list[Formatter] = DEFAULT_FORMATTERS,
     parent_scoped_naming: bool = False,
+    exclude_typename_field: bool = False,
 ) -> None:
     remote_text_cache: DefaultPutDict[str, str] = DefaultPutDict()
     if isinstance(input_, str):
@@ -331,6 +332,7 @@ def generate(  # noqa: PLR0912, PLR0913, PLR0914, PLR0915
         from datamodel_code_generator.parser.graphql import GraphQLParser  # noqa: PLC0415
 
         parser_class: type[Parser] = GraphQLParser
+        kwargs["exclude_typename_field"] = exclude_typename_field
     else:
         from datamodel_code_generator.parser.jsonschema import JsonSchemaParser  # noqa: PLC0415
 

src/datamodel_code_generator/__main__.py

@@ -317,6 +317,7 @@ def validate_root(cls, values: Any) -> Any:  # noqa: N805
     no_alias: bool = False
     formatters: list[Formatter] = DEFAULT_FORMATTERS
     parent_scoped_naming: bool = False
+    exclude_typename_field: bool = False
 
     def merge_args(self, args: Namespace) -> None:
         set_args = {f: getattr(args, f) for f in self.get_fields() if getattr(args, f) is not None}
@@ -531,6 +532,7 @@ def main(args: Sequence[str] | None = None) -> Exit:  # noqa: PLR0911, PLR0912,
             no_alias=config.no_alias,
             formatters=config.formatters,
             parent_scoped_naming=config.parent_scoped_naming,
+            exclude_typename_field=config.exclude_typename_field,
         )
     except InvalidClassNameError as e:
         print(f"{e} You have to set `--class-name` option", file=sys.stderr)  # noqa: T201

src/datamodel_code_generator/arguments.py

@@ -404,6 +404,13 @@ def start_section(self, heading: str | None) -> None:
     action="store_true",
     default=None,
 )
+field_options.add_argument(
+    "--exclude-typename-field",
+    "--exclude_typename_field",
+    help="Exclude __typename field from the generated model",
+    action="store_true",
+    default=None,
+)
 
 # ======================================================================================
 # Options for templating output

src/datamodel_code_generator/parser/graphql.py

@@ -158,6 +158,7 @@ def __init__(  # noqa: PLR0913
         no_alias: bool = False,
         formatters: list[Formatter] = DEFAULT_FORMATTERS,
         parent_scoped_naming: bool = False,
+        exclude_typename_field: bool = False,
     ) -> None:
         super().__init__(
             source=source,
@@ -241,6 +242,7 @@ def __init__(  # noqa: PLR0913
         self.data_model_union_type = data_model_union_type
         self.use_standard_collections = use_standard_collections
         self.use_union_operator = use_union_operator
+        self.exclude_typename_field = exclude_typename_field
 
     def _get_context_source_path_parts(self) -> Iterator[tuple[Source, list[str]]]:
         # TODO (denisart): Temporarily this method duplicates
@@ -450,8 +452,8 @@ def parse_object_like(
 
             data_model_field_type = self.parse_field(field_name_, alias, field)
             fields.append(data_model_field_type)
-
-        fields.append(self._typename_field(obj.name))
+        if not self.exclude_typename_field:
+            fields.append(self._typename_field(obj.name))
 
         base_classes = []
         if hasattr(obj, "interfaces"):  # pragma: no cover

tests/data/expected/parser/graphql/exclude_typename_field.py

@@ -0,0 +1,24 @@
+# generated by datamodel-codegen:
+#   filename:  exclude-typename-field.graphql
+#   timestamp: 2019-07-26T00:00:00+00:00
+
+from __future__ import annotations
+
+from typing import TypeAlias
+
+from pydantic import BaseModel
+
+Boolean: TypeAlias = bool
+"""
+The `Boolean` scalar type represents `true` or `false`.
+"""
+
+
+String: TypeAlias = str
+"""
+The `String` scalar type represents textual data, represented as UTF-8 character sequences. The String type is most often used by GraphQL to represent free-form human-readable text.
+"""
+
+
+class A(BaseModel):
+    field: String

tests/data/graphql/exclude-typename-field.graphql

@@ -0,0 +1,3 @@
+type A {
+  field: String!
+}

tests/parser/test_graphql.py

@@ -47,3 +47,20 @@ def test_graphql_union_aliased_bug() -> None:
         if actual != expected:
             pass
         assert actual == expected
+
+
+@freeze_time("2019-07-26")
+def test_main_graphql_exclude_typename_field() -> None:
+    with TemporaryDirectory() as output_dir:
+        output_file: Path = Path(output_dir) / "output.py"
+        return_code: Exit = main([
+            "--input",
+            str(GRAPHQL_DATA_PATH / "exclude-typename-field.graphql"),
+            "--output",
+            str(output_file),
+            "--input-file-type",
+            "graphql",
+            "--exclude-typename-field",
+        ])
+        assert return_code == Exit.OK
+        assert output_file.read_text() == (EXPECTED_GRAPHQL_PATH / "exclude_typename_field.py").read_text()