Support schema references

[LadnovSasha]

Describe the bug
If swagger.json contains a reference like:

"SchemaA": {
    "$ref": "#/components/schemas/SchemaB"
},

python client unable to generate a proper model for this definition

To Reproduce
Steps to reproduce the behavior:

1. Define a swagger.json that contains a reference to another model
2. Generate a client openapi-python-client generate --path swagger.json

Expected behavior
Client should contain generated endpoint and contain a model

OpenAPI Spec File

{
	"components": {
		"examples": {},
		"headers": {},
		"parameters": {},
		"requestBodies": {},
		"responses": {},
		"schemas": {
			"SchemaB_string_": {
				"properties": {
					"foo": {
						"type": "string"
					}
				},
				"required": [
					"foo"
				],
				"type": "object",
				"additionalProperties": true
			},
			"SchemaA": {
				"$ref": "#/components/schemas/SchemaB_string_"
			}
		},
		"securitySchemes": {}
	},
	"info": {
		"title": "bar-service",
		"version": "1.0.0",
		"description": "bar service",
		"license": {
			"name": "ISC"
		}
	},
	"openapi": "3.0.0",
	"paths": {
		"/foo": {
			"post": {
				"operationId": "Foo",
				"responses": {
					"200": {
						"description": "Ok",
						"content": {
							"application/json": {
								"schema": {
									"$ref": "#/components/schemas/SchemaA"
								}
							}
						}
					}
				},
				"tags": [
					"foobar"
				],
				"security": [],
				"parameters": [],
				"requestBody": {
					"required": true,
					"content": {
						"application/json": {
							"schema": {
								"$ref": "#/components/schemas/SchemaA"
							}
						}
					}
				}
			}
		}
	},
	"servers": [
		{
			"url": "/"
		}
	]
}

Desktop (please complete the following information):

• OS: macOS
• Python Version: 3.9.9
• openapi-python-client version: 0.13.1

Additional context

Stdout:

Generating bar-service-client
Warning(s) encountered while generating. Client was generated, but some pieces may be missing

WARNING parsing POST /foo within foobar. Endpoint will not be generated.

Could not find reference in parsed models or enums

Reference(ref='#/components/schemas/SchemaA')

Unable to parse this part of your OpenAPI document: 

Reference schemas are not supported.

Reference(ref='#/components/schemas/SchemaB_string_')

[joaonc]

Yes please!

Currently reference schemas are explicitly not supported (here), but it's unclear why as adding this support seems not too difficult and increasingly necessary, especially as more people use TypeScript with models defined in objects (const or type instead of interface). TS linters (Pretty, at least) discourages the use of interface in favor of type, which creates the reference schema.

[dbanty]

Folks seem to really want to vote for features, given all the “+1”, so I’m converting features to discussions so y’all can click the up arrow instead. Then, anyone contributing code can sort by most-voted-for 😁.

[dbanty]

Deleted the comments since they don’t add much. Please upvote instead

[wallagib]

I was able to do (at least 1-level-deep) refs in a really naive way by just pulling out the reference and passing it on as an override.

1. Is there anything glaringly wrong with this? It seems to generate correct code for my use case.
2. Is this worth PRing as an incremental push towards full ref support?

index e692ce5..a66ccf7 100644
--- a/openapi_python_client/parser/properties/__init__.py
+++ b/openapi_python_client/parser/properties/__init__.py
@@ -289,6 +289,7 @@ def _create_schemas(
     to_process: Iterable[tuple[str, oai.Reference | oai.Schema]] = components.items()
     still_making_progress = True
     errors: list[PropertyError] = []
+    ref_override = None
 
     # References could have forward References so keep going as long as we are making progress
     while still_making_progress:
@@ -298,13 +299,13 @@ def _create_schemas(
         # Only accumulate errors from the last round, since we might fix some along the way
         for name, data in to_process:
             if isinstance(data, oai.Reference):
-                schemas.errors.append(PropertyError(data=data, detail="Reference schemas are not supported."))
-                continue
+                ref_override = data.ref
             ref_path = parse_reference_path(f"#/components/schemas/{name}")
             if isinstance(ref_path, ParseError):
                 schemas.errors.append(PropertyError(detail=ref_path.detail, data=data))
                 continue
-            schemas_or_err = update_schemas_with_data(ref_path=ref_path, data=data, schemas=schemas, config=config)
+            schemas_or_err = update_schemas_with_data(ref_path=ref_path, data=data, schemas=schemas, config=config, ref_override=ref_override)
             if isinstance(schemas_or_err, PropertyError):
                 next_round.append((name, data))
                 errors.append(schemas_or_err)

index 9e4fc54..7eeaa9f 100644
--- a/openapi_python_client/parser/properties/schemas.py
+++ b/openapi_python_client/parser/properties/schemas.py
@@ -91,7 +91,7 @@ class Schemas:
 
 
 def update_schemas_with_data(
-    *, ref_path: ReferencePath, data: oai.Schema, schemas: Schemas, config: Config
+    *, ref_path: ReferencePath, data: oai.Schema, schemas: Schemas, config: Config, ref_override: ReferencePath = None,
 ) -> Union[Schemas, PropertyError]:
     """
     Update a `Schemas` using some new reference.
@@ -120,7 +120,7 @@ def update_schemas_with_data(
         config=config,
         # Don't process ModelProperty properties because schemas are still being created
         process_properties=False,
-        roots={ref_path},
+        roots={ref_path if ref_override is None else ref_override},
     )
 
     if isinstance(prop, PropertyError):

[Gaff]

Related perhaps:

My scheme wants to append apiKey=<blah> to every query, here's the description:

  securitySchemes:
    ApiKey:
      type: apiKey
      name: apiKey
      in: query

This seems to be supported by httpx - just pass a parameters array into the constructor. For now I've bodged this by bringing my own httpx Client, but it would be good of the client code could cover thisoption in exactly the same way it covers headers.