don't declare unused variable if model has no properties (#1109)

Fixes #1108.

Co-authored-by: Dylan Anthony <43723790+dbanty@users.noreply.github.com>

Author: eli-bl

.changeset/no_properties_fix.md

@@ -0,0 +1,7 @@
+---
+default: patch
+---
+
+# Produce valid code for an object that has no properties at all
+
+Fixed by PR #1109. Thanks @eli-bl!

end_to_end_tests/baseline_openapi_3.0.json

@@ -2219,6 +2219,11 @@
           }
         ]
       },
+      "ModelWithNoProperties": {
+        "type": "object",
+        "properties": {},
+        "additionalProperties": false
+      },
       "AllOfSubModel": {
         "title": "AllOfSubModel",
         "type": "object",

end_to_end_tests/baseline_openapi_3.1.yaml

@@ -2213,6 +2213,11 @@ info:
         }
       ]
     },
+    "ModelWithNoProperties": {
+      "type": "object",
+      "properties": {},
+      "additionalProperties": false
+    },
     "AllOfSubModel": {
       "title": "AllOfSubModel",
       "type": "object",

end_to_end_tests/golden-record/my_test_api_client/models/__init__.py

@@ -60,6 +60,7 @@
 from .model_with_circular_ref_in_additional_properties_b import ModelWithCircularRefInAdditionalPropertiesB
 from .model_with_date_time_property import ModelWithDateTimeProperty
 from .model_with_discriminated_union import ModelWithDiscriminatedUnion
+from .model_with_no_properties import ModelWithNoProperties
 from .model_with_primitive_additional_properties import ModelWithPrimitiveAdditionalProperties
 from .model_with_primitive_additional_properties_a_date_holder import ModelWithPrimitiveAdditionalPropertiesADateHolder
 from .model_with_property_ref import ModelWithPropertyRef
@@ -137,6 +138,7 @@
     "ModelWithCircularRefInAdditionalPropertiesB",
     "ModelWithDateTimeProperty",
     "ModelWithDiscriminatedUnion",
+    "ModelWithNoProperties",
     "ModelWithPrimitiveAdditionalProperties",
     "ModelWithPrimitiveAdditionalPropertiesADateHolder",
     "ModelWithPropertyRef",

end_to_end_tests/golden-record/my_test_api_client/models/model_with_no_properties.py

@@ -0,0 +1,21 @@
+from typing import Any, Dict, Type, TypeVar
+
+from attrs import define as _attrs_define
+
+T = TypeVar("T", bound="ModelWithNoProperties")
+
+
+@_attrs_define
+class ModelWithNoProperties:
+    """ """
+
+    def to_dict(self) -> Dict[str, Any]:
+        field_dict: Dict[str, Any] = {}
+
+        return field_dict
+
+    @classmethod
+    def from_dict(cls: Type[T], src_dict: Dict[str, Any]) -> T:
+        model_with_no_properties = cls()
+
+        return model_with_no_properties

openapi_python_client/templates/model.py.jinja

@@ -138,6 +138,7 @@ return field_dict
     {% for lazy_import in model.lazy_imports %}
         {{ lazy_import }}
     {% endfor %}
+{% if (model.required_properties or model.optional_properties or model.additional_properties) %}
         d = src_dict.copy()
 {% for property in model.required_properties + model.optional_properties %}
     {% if property.required %}
@@ -153,6 +154,7 @@ return field_dict
     {% endif %}
 
 {% endfor %}
+{% endif %}
         {{ module_name }} = cls(
 {% for property in model.required_properties + model.optional_properties %}
             {{ property.python_name }}={{ property.python_name }},