pass models & enums as lists so custom templates can use them (#1189)

Resolves #1188.

The change is simply to store a list, rather than a generator
expression.

The new `models_init.py.jinja` template in the end-to-end tests shows
that this now works. Without the fix in `openapi.py`, this template is
rendered with nothing under the `Using "openapi.models"` and `Using
"openapi.enums"` headings.

This fix is somewhat important for our use case, because we need to put
some code in `models/__init__.py` that is aware of what the model class
names and modules are. Without the fix, the only way to get this would
be to iterate over `imports`, which gives you strings like `from
.module_name import ClassName`, and then parse those strings, which is
workable but pretty clunky.

Author: eli-bl

Diff for: .changeset/fix-models-enums-lists.md

@@ -0,0 +1,11 @@
+---
+default: patch
+---
+
+# Make lists of models and enums work correctly in custom templates
+
+Lists of model and enum classes should be available to custom templates via the Jinja
+variables `openapi.models` and `openapi.enums`, but these were being passed in a way that made
+them always appear empty. This has been fixed so a custom template can now iterate over them.
+
+Closes #1188.

Diff for: end_to_end_tests/custom-templates-golden-record/my_test_api_client/models/__init__.py

@@ -0,0 +1,16 @@
+# Testing that we can access model-related information via Jinja variables.
+
+# To avoid having to update this file in the golden record every time the test specs are changed,
+# we won't include all the classes in this output - we'll just look for one of them.
+
+# Using "alls"
+#   AModel
+
+# Using "imports"
+#   from .a_model import AModel
+
+# Using "openapi.models"
+#   AModel (a_model)
+
+# Using "openapi.enums"
+#   AnEnum (an_enum)

Diff for: end_to_end_tests/test_custom_templates/models_init.py.jinja

@@ -0,0 +1,33 @@
+
+# Testing that we can access model-related information via Jinja variables.
+
+# To avoid having to update this file in the golden record every time the test specs are changed,
+# we won't include all the classes in this output - we'll just look for one of them.
+
+# Using "alls"
+{% for name in alls %}
+{% if name == "AModel" %}
+#   {{ name }}
+{% endif %}
+{% endfor %}
+
+# Using "imports"
+{% for import in imports %}
+{% if import.endswith("import AModel") %}
+#   {{ import }}
+{% endif %}
+{% endfor %}
+
+# Using "openapi.models"
+{% for model in openapi.models %}
+{% if model.class_info.name == "AModel" %}
+#   {{ model.class_info.name }} ({{ model.class_info.module_name }})
+{% endif %}
+{% endfor %}
+
+# Using "openapi.enums"
+{% for enum in openapi.enums %}
+{% if enum.class_info.name == "AnEnum" %}
+#   {{ enum.class_info.name }} ({{ enum.class_info.module_name }})
+{% endif %}
+{% endfor %}

Diff for: end_to_end_tests/test_end_to_end.py

@@ -185,13 +185,15 @@ def test_custom_templates():
         {}
     )  # key: path relative to generated directory, value: expected generated content
     api_dir = Path("my_test_api_client").joinpath("api")
+    models_dir = Path("my_test_api_client").joinpath("models")
     golden_tpls_root_dir = Path(__file__).parent.joinpath(
         "custom-templates-golden-record"
     )
 
     expected_difference_paths = [
         Path("README.md"),
         api_dir.joinpath("__init__.py"),
+        models_dir.joinpath("__init__.py"),
     ]
 
     for expected_difference_path in expected_difference_paths:

Diff for: openapi_python_client/parser/openapi.py

@@ -508,10 +508,10 @@ class GeneratorData:
     title: str
     description: Optional[str]
     version: str
-    models: Iterator[ModelProperty]
+    models: list[ModelProperty]
     errors: list[ParseError]
     endpoint_collections_by_tag: dict[utils.PythonIdentifier, EndpointCollection]
-    enums: Iterator[Union[EnumProperty, LiteralEnumProperty]]
+    enums: list[Union[EnumProperty, LiteralEnumProperty]]
 
     @staticmethod
     def from_dict(data: dict[str, Any], *, config: Config) -> Union["GeneratorData", GeneratorError]:
@@ -546,10 +546,10 @@ def from_dict(data: dict[str, Any], *, config: Config) -> Union["GeneratorData",
             config=config,
         )
 
-        enums = (
+        enums = [
             prop for prop in schemas.classes_by_name.values() if isinstance(prop, (EnumProperty, LiteralEnumProperty))
-        )
-        models = (prop for prop in schemas.classes_by_name.values() if isinstance(prop, ModelProperty))
+        ]
+        models = [prop for prop in schemas.classes_by_name.values() if isinstance(prop, ModelProperty)]
 
         return GeneratorData(
             title=openapi.info.title,