Fix empty array items to generate List[Any] instead of bare List (#2584)

koxudaxi · claude · web-flow · commit 40adf78a3701 · 2025-12-02T22:01:16.000+09:00
* Fix handling of empty items in lists to use List[Any] for mypy compliance * Update remaining expected test files for List[Any] change 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude <noreply@anthropic.com> --------- Co-authored-by: Claude <noreply@anthropic.com>
diff --git a/src/datamodel_code_generator/parser/jsonschema.py b/src/datamodel_code_generator/parser/jsonschema.py
@@ -1364,15 +1364,20 @@ def parse_array_fields(
         else:
             items = []
 
+        if items:
+            item_data_types = self.parse_list_item(
+                name,
+                items,
+                path,
+                obj,
+                singular_name=singular_name,
+            )
+        else:
+            item_data_types = [self.data_type_manager.get_data_type(Types.any)]
+
         data_types: list[DataType] = [
             self.data_type(
-                data_types=self.parse_list_item(
-                    name,
-                    items,
-                    path,
-                    obj,
-                    singular_name=singular_name,
-                ),
+                data_types=item_data_types,
                 is_list=True,
             )
         ]
diff --git a/tests/data/expected/main/jsonschema/autodetect.py b/tests/data/expected/main/jsonschema/autodetect.py
@@ -4,7 +4,7 @@
 
 from __future__ import annotations
 
-from typing import List, Optional
+from typing import Any, List, Optional
 
 from pydantic import BaseModel, Field, conint
 
@@ -15,5 +15,5 @@ class Person(BaseModel):
     age: Optional[conint(ge=0)] = Field(
         None, description='Age in years which must be equal to or greater than zero.'
     )
-    friends: Optional[List] = None
+    friends: Optional[List[Any]] = None
     comment: None = None
diff --git a/tests/data/expected/main/jsonschema/custom_formatters.py b/tests/data/expected/main/jsonschema/custom_formatters.py
@@ -8,7 +8,7 @@
 #
 from __future__ import annotations
 
-from typing import List, Optional
+from typing import Any, List, Optional
 
 from pydantic import BaseModel, Field, conint
 
@@ -19,5 +19,5 @@ class Person(BaseModel):
     age: Optional[conint(ge=0)] = Field(
         None, description='Age in years which must be equal to or greater than zero.'
     )
-    friends: Optional[List] = None
+    friends: Optional[List[Any]] = None
     comment: None = None
diff --git a/tests/data/expected/main/jsonschema/forwarding_reference/forwarding.py b/tests/data/expected/main/jsonschema/forwarding_reference/forwarding.py
@@ -14,4 +14,4 @@ class Model(BaseModel):
 
 
 class ForwardingArray(BaseModel):
-    __root__: List
+    __root__: List[Any]
diff --git a/tests/data/expected/main/jsonschema/general.py b/tests/data/expected/main/jsonschema/general.py
@@ -4,7 +4,7 @@
 
 from __future__ import annotations
 
-from typing import List, Optional
+from typing import Any, List, Optional
 
 from pydantic import BaseModel, Field, conint
 
@@ -15,5 +15,5 @@ class Person(BaseModel):
     age: Optional[conint(ge=0)] = Field(
         None, description='Age in years which must be equal to or greater than zero.'
     )
-    friends: Optional[List] = None
+    friends: Optional[List[Any]] = None
     comment: None = None
diff --git a/tests/data/expected/main/jsonschema/general_dataclass_frozen_kw_only.py b/tests/data/expected/main/jsonschema/general_dataclass_frozen_kw_only.py
@@ -5,13 +5,13 @@
 from __future__ import annotations
 
 from dataclasses import dataclass
-from typing import List, Optional
+from typing import Any, List, Optional
 
 
 @dataclass(frozen=True, kw_only=True)
 class Person:
     firstName: Optional[str] = None
     lastName: Optional[str] = None
     age: Optional[int] = None
-    friends: Optional[List] = None
+    friends: Optional[List[Any]] = None
     comment: None = None
diff --git a/tests/data/expected/main/jsonschema/invalid_import_name/array_commons_schema.py b/tests/data/expected/main/jsonschema/invalid_import_name/array_commons_schema.py
@@ -13,5 +13,5 @@ class Commons(RootModel[Any]):
     root: Any = Field(..., description='Commons objects', title='Commons')
 
 
-class DefaultArray(RootModel[List]):
-    root: List = Field(..., max_length=100, min_length=1)
+class DefaultArray(RootModel[List[Any]]):
+    root: List[Any] = Field(..., max_length=100, min_length=1)
diff --git a/tests/data/expected/main/jsonschema/invalid_model_name.py b/tests/data/expected/main/jsonschema/invalid_model_name.py
@@ -4,7 +4,7 @@
 
 from __future__ import annotations
 
-from typing import List, Optional
+from typing import Any, List, Optional
 
 from pydantic import BaseModel, Field, conint
 
@@ -15,5 +15,5 @@ class ValidModelName(BaseModel):
     age: Optional[conint(ge=0)] = Field(
         None, description='Age in years which must be equal to or greater than zero.'
     )
-    friends: Optional[List] = None
+    friends: Optional[List[Any]] = None
     comment: None = None
diff --git a/tests/data/expected/main/jsonschema/items_boolean.py b/tests/data/expected/main/jsonschema/items_boolean.py
@@ -4,10 +4,10 @@
 
 from __future__ import annotations
 
-from typing import List, Optional
+from typing import Any, List, Optional
 
 from pydantic import BaseModel
 
 
 class Model(BaseModel):
-    example: Optional[List] = None
+    example: Optional[List[Any]] = None
diff --git a/tests/data/expected/main/jsonschema/jsonschema_empty_items_array.py b/tests/data/expected/main/jsonschema/jsonschema_empty_items_array.py
@@ -0,0 +1,14 @@
+# generated by datamodel-codegen:
+#   filename:  empty_items_array.json
+#   timestamp: 2019-07-26T00:00:00+00:00
+
+from __future__ import annotations
+
+from typing import Any, Dict, List, Optional
+
+from pydantic import BaseModel
+
+
+class Model(BaseModel):
+    datum_kwargs: Optional[Dict[str, List[Any]]] = None
+    simple_list: Optional[List[Any]] = None
diff --git a/tests/data/expected/main/jsonschema/root_id.py b/tests/data/expected/main/jsonschema/root_id.py
@@ -19,7 +19,7 @@ class Person(BaseModel):
     age: Optional[conint(ge=0)] = Field(
         None, description='Age in years which must be equal to or greater than zero.'
     )
-    friends: Optional[List] = None
+    friends: Optional[List[Any]] = None
     comment: None = None
 
 
diff --git a/tests/data/expected/main/jsonschema/root_id_absolute_url.py b/tests/data/expected/main/jsonschema/root_id_absolute_url.py
@@ -19,7 +19,7 @@ class Person(BaseModel):
     age: Optional[conint(ge=0)] = Field(
         None, description='Age in years which must be equal to or greater than zero.'
     )
-    friends: Optional[List] = None
+    friends: Optional[List[Any]] = None
     comment: None = None
 
 
diff --git a/tests/data/expected/main/jsonschema/same_name_objects.py b/tests/data/expected/main/jsonschema/same_name_objects.py
@@ -21,7 +21,7 @@ class Config:
 
 
 class FriendsModel(BaseModel):
-    __root__: List
+    __root__: List[Any]
 
 
 class Tst2(BaseModel):
diff --git a/tests/data/expected/main/main_jsonschema_with_custom_formatters/output.py b/tests/data/expected/main/main_jsonschema_with_custom_formatters/output.py
@@ -8,7 +8,7 @@
 # 
 from __future__ import annotations
 
-from typing import List, Optional
+from typing import Any, List, Optional
 
 from pydantic import BaseModel, Field, conint
 
@@ -19,5 +19,5 @@ class Person(BaseModel):
     age: Optional[conint(ge=0)] = Field(
         None, description='Age in years which must be equal to or greater than zero.'
     )
-    friends: Optional[List] = None
+    friends: Optional[List[Any]] = None
     comment: None = None
diff --git a/tests/data/jsonschema/empty_items_array.json b/tests/data/jsonschema/empty_items_array.json
@@ -0,0 +1,17 @@
+{
+  "$schema": "http://json-schema.org/draft-07/schema#",
+  "type": "object",
+  "properties": {
+    "datum_kwargs": {
+      "additionalProperties": {
+        "items": {},
+        "type": "array"
+      },
+      "type": "object"
+    },
+    "simple_list": {
+      "items": {},
+      "type": "array"
+    }
+  }
+}
diff --git a/tests/main/jsonschema/test_main_jsonschema.py b/tests/main/jsonschema/test_main_jsonschema.py
@@ -2965,3 +2965,13 @@ def test_main_jsonschema_reuse_scope_tree_typeddict(output_dir: Path) -> None:
         input_file_type="jsonschema",
         extra_args=["--reuse-model", "--reuse-scope", "tree", "--output-model-type", "typing.TypedDict"],
     )
+
+
+def test_main_jsonschema_empty_items_array(output_file: Path) -> None:
+    """Test that arrays with empty items ({}) generate List[Any] instead of bare List."""
+    run_main_and_assert(
+        input_path=JSON_SCHEMA_DATA_PATH / "empty_items_array.json",
+        output_path=output_file,
+        input_file_type="jsonschema",
+        assert_func=assert_file_content,
+    )
diff --git a/tests/parser/test_jsonschema.py b/tests/parser/test_jsonschema.py
@@ -333,8 +333,8 @@ def test_parse_one_of_object(source_obj: dict[str, Any], generated_classes: str)
     string_on_field: Optional[str] = Field('default string', description='description')
     number: Optional[float] = 123
     number_on_field: Optional[float] = Field(123, description='description')
-    number_array: Optional[List] = [1, 2, 3]
-    string_array: Optional[List] = ['a', 'b', 'c']
+    number_array: Optional[List[Any]] = [1, 2, 3]
+    string_array: Optional[List[Any]] = ['a', 'b', 'c']
     object: Optional[Dict[str, Any]] = {'key': 'value'}""",
         )
     ],
diff --git a/tests/parser/test_openapi.py b/tests/parser/test_openapi.py
@@ -131,7 +131,7 @@ class Pets(BaseModel):
         (
             {"properties": {"kind": {"type": "array", "items": []}}},
             """class Pets(BaseModel):
-    kind: Optional[List] = None""",
+    kind: Optional[List[Any]] = None""",
         ),
     ],
 )
@@ -175,7 +175,7 @@ class Pets(BaseModel):
                 "items": {},
             },
             """class Pets(BaseModel):
-    __root__: List""",
+    __root__: List[Any]""",
         ),
     ],
 )

Original file line number	Diff line number	Diff line change
`@@ -8,7 +8,7 @@`
`8`	`8`	`#`
`9`	`9`	`from __future__ import annotations`
`10`	`10`
`11`		`-from typing import List, Optional`
	`11`	`+from typing import Any, List, Optional`
`12`	`12`
`13`	`13`	`from pydantic import BaseModel, Field, conint`
`14`	`14`
`@@ -19,5 +19,5 @@ class Person(BaseModel):`
`19`	`19`	`age: Optional[conint(ge=0)] = Field(`
`20`	`20`	`None, description='Age in years which must be equal to or greater than zero.'`
`21`	`21`	`)`
`22`		`- friends: Optional[List] = None`
	`22`	`+ friends: Optional[List[Any]] = None`
`23`	`23`	`comment: None = None`
Original file line number	Diff line number	Diff line change
`@@ -14,4 +14,4 @@ class Model(BaseModel):`
`14`	`14`
`15`	`15`
`16`	`16`	`class ForwardingArray(BaseModel):`
`17`		`- __root__: List`
	`17`	`+ __root__: List[Any]`