Combines InferringRouter from fastapi-utils and Result from returns so that both primary (200) and additional response types can be inferred from the path operation type signature.
Install as user:
pip install git+https://github.com/amacfie/fastapi_returns_inferring_routerInstall as developer:
pip install --editable .from typing import Literal
from pydantic import BaseModel
from returns.result import Result, Success, Failure
import fastapi
from fastapi_returns_inferring_router import ReturnsInferringRouter
class ForbiddenBecauseOfUser(BaseModel):
def status_code(*args):
return 403
msg: Literal["Forbidden because of user"] = "Forbidden because of user"
class ForbiddenBecauseOfKey(BaseModel):
def status_code(*args):
return 403
msg: Literal["Forbidden because of key"] = "Forbidden because of key"
app = fastapi.FastAPI()
# two params are added to APIRouter
# * get_status_code
# pass a function that can take either a return type or return value and
# returns the HTTP status code you wish to use it for
# * merge_with_existing_responses
# if there's already a responses parameter, if this parameter is True we
# add to it, otherwise we don't touch it
r = ReturnsInferringRouter(
get_status_code=lambda x: x.status_code(),
merge_with_existing_responses=True,
)
# compatible with InferringRouter from fastapi-utils
@r.get("/foo/{bar}")
def foo(bar: str) -> str:
return bar + "b"
# use the Returns library to write a function with a return type of Result.
# the success type becomes the 200 response type
# any failure types are also added as response types under the status code
# given by get_status_code.
# here we have two types with the same status code so the schema for 403 will
# be the union of the two types.
# currently, as with InferringRouter, only stuff that gets encoded as JSON
# is supported, e.g. having FileResponse as a return type won't work well.
# see https://github.com/amacfie/fastapi_returns_inferring_router/issues/2
@r.get("/baz/{bar}")
def baz(bar: str) -> Result[str, ForbiddenBecauseOfKey | ForbiddenBecauseOfUser]:
if ...:
return Failure(ForbiddenBecauseOfKey())
elif ...:
return Failure(ForbiddenBecauseOfUser())
else:
return Success(bar + "b")
app.include_router(r)Generated schema (paste to https://editor.swagger.io/ for nicer view):
{
"openapi": "3.0.2",
"info": {
"title": "FastAPI",
"version": "0.1.0"
},
"paths": {
"/foo/{bar}": {
"get": {
"summary": "Foo",
"operationId": "foo_foo__bar__get",
"parameters": [
{
"required": true,
"schema": {
"title": "Bar",
"type": "string"
},
"name": "bar",
"in": "path"
}
],
"responses": {
"200": {
"description": "Successful Response",
"content": {
"application/json": {
"schema": {
"title": "Response Foo Foo Bar Get",
"type": "string"
}
}
}
},
"422": {
"description": "Validation Error",
"content": {
"application/json": {
"schema": {
"$ref": "#/components/schemas/HTTPValidationError"
}
}
}
}
}
}
},
"/baz/{bar}": {
"get": {
"summary": "Baz",
"operationId": "baz_baz__bar__get",
"parameters": [
{
"required": true,
"schema": {
"title": "Bar",
"type": "string"
},
"name": "bar",
"in": "path"
}
],
"responses": {
"200": {
"description": "Successful Response",
"content": {
"application/json": {
"schema": {
"title": "Response Baz Baz Bar Get",
"type": "string"
}
}
}
},
"403": {
"description": "Forbidden",
"content": {
"application/json": {
"schema": {
"title": "Response 403 Baz Baz Bar Get",
"anyOf": [
{
"$ref": "#/components/schemas/ForbiddenBecauseOfKey"
},
{
"$ref": "#/components/schemas/ForbiddenBecauseOfUser"
}
]
}
}
}
},
"422": {
"description": "Validation Error",
"content": {
"application/json": {
"schema": {
"$ref": "#/components/schemas/HTTPValidationError"
}
}
}
}
}
}
}
},
"components": {
"schemas": {
"ForbiddenBecauseOfKey": {
"title": "ForbiddenBecauseOfKey",
"type": "object",
"properties": {
"msg": {
"title": "Msg",
"enum": [
"Forbidden because of key"
],
"type": "string",
"default": "Forbidden because of key"
}
}
},
"ForbiddenBecauseOfUser": {
"title": "ForbiddenBecauseOfUser",
"type": "object",
"properties": {
"msg": {
"title": "Msg",
"enum": [
"Forbidden because of user"
],
"type": "string",
"default": "Forbidden because of user"
}
}
},
"HTTPValidationError": {
"title": "HTTPValidationError",
"type": "object",
"properties": {
"detail": {
"title": "Detail",
"type": "array",
"items": {
"$ref": "#/components/schemas/ValidationError"
}
}
}
},
"ValidationError": {
"title": "ValidationError",
"required": [
"loc",
"msg",
"type"
],
"type": "object",
"properties": {
"loc": {
"title": "Location",
"type": "array",
"items": {
"anyOf": [
{
"type": "string"
},
{
"type": "integer"
}
]
}
},
"msg": {
"title": "Message",
"type": "string"
},
"type": {
"title": "Error Type",
"type": "string"
}
}
}
}
}
}
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