Fix mutable defaults in generated dataclasses. Closes #53

Author: dbanty

CHANGELOG.md

@@ -34,6 +34,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
     - Client will still be generated if there are recoverable errors, excluding endpoints that had those errors
 - Output from isort and black when generating will now be suppressed
 
+### Fixes
+- Defaults within models dataclasses for `Dict` or `List` properties will now be properly declared as a 
+    `field` with the `default_factory` parameter to prevent errors related to mutable defaults.
+
 ## 0.3.0 - 2020-04-25
 ### Additions
 - Link to the GitHub repository from PyPI (#26). Thanks @theY4Kman!

end_to_end_tests/fastapi_app/__init__.py

@@ -3,7 +3,7 @@
 from datetime import date, datetime
 from enum import Enum
 from pathlib import Path
-from typing import List, Union
+from typing import Any, Dict, List, Union
 
 from fastapi import APIRouter, FastAPI, File, Query, UploadFile
 from pydantic import BaseModel
@@ -42,7 +42,8 @@ class AModel(BaseModel):
     """ A Model for testing all the ways custom objects can be used """
 
     an_enum_value: AnEnum
-    nested_list_of_enums: List[List[DifferentEnum]]
+    nested_list_of_enums: List[List[DifferentEnum]] = []
+    some_dict: Dict[str, str] = {}
     aCamelDateTime: Union[datetime, date]
     a_date: date
 

end_to_end_tests/fastapi_app/openapi.json

@@ -144,7 +144,6 @@
                 "title": "AModel",
                 "required": [
                     "an_enum_value",
-                    "nested_list_of_enums",
                     "aCamelDateTime",
                     "a_date"
                 ],
@@ -168,7 +167,16 @@
                                     "OTHER"
                                 ]
                             }
-                        }
+                        },
+                        "default": []
+                    },
+                    "some_dict": {
+                        "title": "Some Dict",
+                        "type": "object",
+                        "additionalProperties": {
+                            "type": "string"
+                        },
+                        "default": {}
                     },
                     "aCamelDateTime": {
                         "title": "Acameldatetime",

end_to_end_tests/golden-master/my_test_api_client/models/a_model.py

@@ -1,8 +1,8 @@
 from __future__ import annotations
 
-from dataclasses import dataclass
+from dataclasses import dataclass, field
 from datetime import date, datetime
-from typing import Any, Dict, List, Union, cast
+from typing import Any, Dict, List, Optional, Union, cast
 
 from .an_enum_value import AnEnumValue
 from .an_enum_value1 import AnEnumValue1
@@ -13,23 +13,16 @@ class AModel:
     """ A Model for testing all the ways custom objects can be used  """
 
     an_enum_value: AnEnumValue
-    nested_list_of_enums: List[List[AnEnumValue1]]
     a_camel_date_time: Union[datetime, date]
     a_date: date
+    nested_list_of_enums: Optional[List[List[AnEnumValue1]]] = field(
+        default_factory=lambda: cast(Optional[List[List[AnEnumValue1]]], [])
+    )
+    some_dict: Optional[Dict[Any, Any]] = field(default_factory=lambda: cast(Optional[Dict[Any, Any]], {}))
 
     def to_dict(self) -> Dict[str, Any]:
         an_enum_value = self.an_enum_value.value
 
-        nested_list_of_enums = []
-        for nested_list_of_enums_item_data in self.nested_list_of_enums:
-            nested_list_of_enums_item = []
-            for nested_list_of_enums_item_item_data in nested_list_of_enums_item_data:
-                nested_list_of_enums_item_item = nested_list_of_enums_item_item_data.value
-
-                nested_list_of_enums_item.append(nested_list_of_enums_item_item)
-
-            nested_list_of_enums.append(nested_list_of_enums_item)
-
         if isinstance(self.a_camel_date_time, datetime):
             a_camel_date_time = self.a_camel_date_time.isoformat()
 
@@ -38,27 +31,33 @@ def to_dict(self) -> Dict[str, Any]:
 
         a_date = self.a_date.isoformat()
 
+        if self.nested_list_of_enums is None:
+            nested_list_of_enums = None
+        else:
+            nested_list_of_enums = []
+            for nested_list_of_enums_item_data in self.nested_list_of_enums:
+                nested_list_of_enums_item = []
+                for nested_list_of_enums_item_item_data in nested_list_of_enums_item_data:
+                    nested_list_of_enums_item_item = nested_list_of_enums_item_item_data.value
+
+                    nested_list_of_enums_item.append(nested_list_of_enums_item_item)
+
+                nested_list_of_enums.append(nested_list_of_enums_item)
+
+        some_dict = self.some_dict
+
         return {
             "an_enum_value": an_enum_value,
-            "nested_list_of_enums": nested_list_of_enums,
             "aCamelDateTime": a_camel_date_time,
             "a_date": a_date,
+            "nested_list_of_enums": nested_list_of_enums,
+            "some_dict": some_dict,
         }
 
     @staticmethod
     def from_dict(d: Dict[str, Any]) -> AModel:
         an_enum_value = AnEnumValue(d["an_enum_value"])
 
-        nested_list_of_enums = []
-        for nested_list_of_enums_item_data in d["nested_list_of_enums"]:
-            nested_list_of_enums_item = []
-            for nested_list_of_enums_item_item_data in nested_list_of_enums_item_data:
-                nested_list_of_enums_item_item = AnEnumValue1(nested_list_of_enums_item_item_data)
-
-                nested_list_of_enums_item.append(nested_list_of_enums_item_item)
-
-            nested_list_of_enums.append(nested_list_of_enums_item)
-
         def _parse_a_camel_date_time(data: Dict[str, Any]) -> Union[datetime, date]:
             a_camel_date_time: Union[datetime, date]
             try:
@@ -75,9 +74,22 @@ def _parse_a_camel_date_time(data: Dict[str, Any]) -> Union[datetime, date]:
 
         a_date = date.fromisoformat(d["a_date"])
 
+        nested_list_of_enums = []
+        for nested_list_of_enums_item_data in d.get("nested_list_of_enums") or []:
+            nested_list_of_enums_item = []
+            for nested_list_of_enums_item_item_data in nested_list_of_enums_item_data:
+                nested_list_of_enums_item_item = AnEnumValue1(nested_list_of_enums_item_item_data)
+
+                nested_list_of_enums_item.append(nested_list_of_enums_item_item)
+
+            nested_list_of_enums.append(nested_list_of_enums_item)
+
+        some_dict = d.get("some_dict")
+
         return AModel(
             an_enum_value=an_enum_value,
-            nested_list_of_enums=nested_list_of_enums,
             a_camel_date_time=a_camel_date_time,
             a_date=a_date,
+            nested_list_of_enums=nested_list_of_enums,
+            some_dict=some_dict,
         )

openapi_python_client/openapi_parser/properties.py

@@ -176,6 +176,11 @@ class ListProperty(Property, Generic[InnerProp]):
     inner_property: InnerProp
     template: ClassVar[str] = "list_property.pyi"
 
+    def __post_init__(self) -> None:
+        super().__post_init__()
+        if self.default is not None:
+            self.default = f"field(default_factory=lambda: cast({self.get_type_string()}, {self.default}))"
+
     def get_type_string(self) -> str:
         """ Get a string representation of type that should be used when declaring this property """
         if self.required:
@@ -192,6 +197,9 @@ def get_imports(self, *, prefix: str) -> Set[str]:
         imports = super().get_imports(prefix=prefix)
         imports.update(self.inner_property.get_imports(prefix=prefix))
         imports.add("from typing import List")
+        if self.default is not None:
+            imports.add("from dataclasses import field")
+            imports.add("from typing import cast")
         return imports
 
 
@@ -331,6 +339,11 @@ class DictProperty(Property):
 
     _type_string: ClassVar[str] = "Dict[Any, Any]"
 
+    def __post_init__(self) -> None:
+        super().__post_init__()
+        if self.default is not None:
+            self.default = f"field(default_factory=lambda: cast({self.get_type_string()}, {self.default}))"
+
     def get_imports(self, *, prefix: str) -> Set[str]:
         """
         Get a set of import strings that should be included when this property is used somewhere
@@ -340,6 +353,9 @@ def get_imports(self, *, prefix: str) -> Set[str]:
         """
         imports = super().get_imports(prefix=prefix)
         imports.add("from typing import Dict")
+        if self.default is not None:
+            imports.add("from dataclasses import field")
+            imports.add("from typing import cast")
         return imports
 
 
@@ -391,7 +407,7 @@ def property_from_dict(name: str, required: bool, data: Dict[str, Any]) -> Prope
         return ListProperty(
             name=name,
             required=required,
-            default=None,
+            default=data.get("default"),
             inner_property=property_from_dict(name=f"{name}_item", required=True, data=data["items"]),
         )
     elif data["type"] == "object":

tests/test_openapi_parser/test_properties.py

@@ -130,6 +130,9 @@ def test_get_type_string(self, mocker):
         p.required = False
         assert p.get_type_string() == f"Optional[List[{inner_type_string}]]"
 
+        p = ListProperty(name="test", required=True, default=[], inner_property=inner_property)
+        assert p.default == f"field(default_factory=lambda: cast(List[{inner_type_string}], []))"
+
     def test_get_type_imports(self, mocker):
         from openapi_python_client.openapi_parser.properties import ListProperty
 
@@ -150,6 +153,15 @@ def test_get_type_imports(self, mocker):
             "from typing import Optional",
         }
 
+        p.default = mocker.MagicMock()
+        assert p.get_imports(prefix=prefix) == {
+            inner_import,
+            "from typing import Optional",
+            "from typing import List",
+            "from typing import cast",
+            "from dataclasses import field",
+        }
+
 
 class TestUnionProperty:
     def test_get_type_string(self, mocker):
@@ -328,6 +340,12 @@ def test_get_imports(self, mocker):
 
 
 class TestDictProperty:
+    def test___post_init__(self):
+        from openapi_python_client.openapi_parser.properties import DictProperty
+
+        p = DictProperty(name="blah", required=True, default={})
+        assert p.default == "field(default_factory=lambda: cast(Dict[Any, Any], {}))"
+
     def test_get_imports(self, mocker):
         from openapi_python_client.openapi_parser.properties import DictProperty
 
@@ -345,6 +363,14 @@ def test_get_imports(self, mocker):
             "from typing import Dict",
         }
 
+        p.default = mocker.MagicMock()
+        assert p.get_imports(prefix=prefix) == {
+            "from typing import Optional",
+            "from typing import Dict",
+            "from typing import cast",
+            "from dataclasses import field",
+        }
+
 
 class TestPropertyFromDict:
     def test_property_from_dict_enum(self, mocker):