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.

[aletor123]

+1

[M1troll]

+1

[yu-iskw]

+1

[authentichamza]

+1

[paulo-raca]

+1

[seanhumbarger]

+1

[Mexflubber]

+1

[mikedavidson-evertz]

+1

[rshah-evertz]

+1

[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 😁.