Bug: Optional types generate incorrect OpenAPI schemas

[nilsso]

Describe the bug

1. Optional types in query parameters don't seem to play well with OpenAPI, resulting in a bad schema, except that upon some more testing if there is more than one non-None type in the annotation it works.

A query parameter annotated int | None produces incorrectly:

{ "oneOf": [
    { "type": null" },
    { "oneOf": [] }
]}

While one annotated int | str | date | None produces correctly:

{ "oneOf": [
    { "type": "null" },
    { "type": "integer" },
    { "type": "string" },
    { "type": "string", "format": "date" }
]}

2. Additionally, optional types are being assumed to be optional parameters, resulting in "required": false regardless of whether the parameter has a default value or not.

3. And finally, route return types that are optional are mostly correct, but for some reason include an empty node (e.g. { "oneOf": [ { "type": "null" }, { "type": "integer" }, {} }). This results in /schema/redoc including a possible type of Any.

To Reproduce

(I ran this on 3.11, but IIRC 3.8+ for | None should work. I also tried with Optional and got the same results.)

As a minimal example:

# starlite_optionals.py
from datetime import date

from starlite import Starlite, get


@get("/a")
def a(v: int | None) -> int | None:
    return v


@get("/b")
def b(v: int | str | date | None) -> int | str | date | None:
    return v


@get("/c")
def c(v: int | None = None) -> int | None:
    return v


@get("/d")
def d(v: int | str | date | None = None) -> int | str | date | None:
    return v


app = Starlite(route_handlers=[a, b, c, d], debug=True)

Check the generated schema below, or by running uvicorn starlite_optionals:app and navigating to http://127.0.0.1:8000/schema/openapi.json and/or http://127.0.0.1:8000/schema/.

Generated OpenAPI schema.

{
  "openapi": "3.1.0",
  "info": {
    "title": "Starlite API",
    "version": "1.0.0"
  },
  "servers": [
    {
      "url": "/"
    }
  ],
  "paths": {
    "/a": {
      "get": {
        "operationId": "AA",
        "parameters": [
          {
            "name": "v",
            "in": "query",
            "required": false,
            "deprecated": false,
            "allowEmptyValue": false,
            "allowReserved": false,
            "schema": {
              "oneOf": [
                {
                  "type": "null"
                },
                {
                  "oneOf": []
                }
              ]
            }
          }
        ],
        "responses": {
          "200": {
            "description": "Request fulfilled, document follows",
            "headers": {},
            "content": {
              "application/json": {
                "schema": {
                  "oneOf": [
                    {
                      "type": "null"
                    },
                    {
                      "type": "integer"
                    },
                    {}
                  ]
                }
              }
            }
          },
          "400": {
            "description": "Bad request syntax or unsupported method",
            "content": {
              "application/json": {
                "schema": {
                  "properties": {
                    "status_code": {
                      "type": "integer"
                    },
                    "detail": {
                      "type": "string"
                    },
                    "extra": {
                      "additionalProperties": {},
                      "type": [
                        "null",
                        "object",
                        "array"
                      ]
                    }
                  },
                  "type": "object",
                  "required": [
                    "detail",
                    "status_code"
                  ],
                  "description": "Validation Exception",
                  "examples": [
                    {
                      "status_code": 400,
                      "detail": "Bad Request",
                      "extra": {}
                    }
                  ]
                }
              }
            }
          }
        },
        "deprecated": false
      }
    },
    "/b": {
      "get": {
        "operationId": "BB",
        "parameters": [
          {
            "name": "v",
            "in": "query",
            "required": false,
            "deprecated": false,
            "allowEmptyValue": false,
            "allowReserved": false,
            "schema": {
              "oneOf": [
                {
                  "type": "null"
                },
                {
                  "type": "integer"
                },
                {
                  "type": "string"
                },
                {
                  "type": "string",
                  "format": "date"
                }
              ]
            }
          }
        ],
        "responses": {
          "200": {
            "description": "Request fulfilled, document follows",
            "headers": {},
            "content": {
              "application/json": {
                "schema": {
                  "oneOf": [
                    {
                      "type": "null"
                    },
                    {
                      "type": "integer"
                    },
                    {
                      "type": "string"
                    },
                    {
                      "type": "string",
                      "format": "date"
                    },
                    {}
                  ]
                }
              }
            }
          },
          "400": {
            "description": "Bad request syntax or unsupported method",
            "content": {
              "application/json": {
                "schema": {
                  "properties": {
                    "status_code": {
                      "type": "integer"
                    },
                    "detail": {
                      "type": "string"
                    },
                    "extra": {
                      "additionalProperties": {},
                      "type": [
                        "null",
                        "object",
                        "array"
                      ]
                    }
                  },
                  "type": "object",
                  "required": [
                    "detail",
                    "status_code"
                  ],
                  "description": "Validation Exception",
                  "examples": [
                    {
                      "status_code": 400,
                      "detail": "Bad Request",
                      "extra": {}
                    }
                  ]
                }
              }
            }
          }
        },
        "deprecated": false
      }
    },
    "/c": {
      "get": {
        "operationId": "CC",
        "parameters": [
          {
            "name": "v",
            "in": "query",
            "required": false,
            "deprecated": false,
            "allowEmptyValue": false,
            "allowReserved": false,
            "schema": {
              "oneOf": [
                {
                  "type": "null"
                },
                {
                  "oneOf": []
                }
              ]
            }
          }
        ],
        "responses": {
          "200": {
            "description": "Request fulfilled, document follows",
            "headers": {},
            "content": {
              "application/json": {
                "schema": {
                  "oneOf": [
                    {
                      "type": "null"
                    },
                    {
                      "type": "integer"
                    },
                    {}
                  ]
                }
              }
            }
          },
          "400": {
            "description": "Bad request syntax or unsupported method",
            "content": {
              "application/json": {
                "schema": {
                  "properties": {
                    "status_code": {
                      "type": "integer"
                    },
                    "detail": {
                      "type": "string"
                    },
                    "extra": {
                      "additionalProperties": {},
                      "type": [
                        "null",
                        "object",
                        "array"
                      ]
                    }
                  },
                  "type": "object",
                  "required": [
                    "detail",
                    "status_code"
                  ],
                  "description": "Validation Exception",
                  "examples": [
                    {
                      "status_code": 400,
                      "detail": "Bad Request",
                      "extra": {}
                    }
                  ]
                }
              }
            }
          }
        },
        "deprecated": false
      }
    },
    "/d": {
      "get": {
        "operationId": "DD",
        "parameters": [
          {
            "name": "v",
            "in": "query",
            "required": false,
            "deprecated": false,
            "allowEmptyValue": false,
            "allowReserved": false,
            "schema": {
              "oneOf": [
                {
                  "type": "null"
                },
                {
                  "type": "integer"
                },
                {
                  "type": "string"
                },
                {
                  "type": "string",
                  "format": "date"
                }
              ]
            }
          }
        ],
        "responses": {
          "200": {
            "description": "Request fulfilled, document follows",
            "headers": {},
            "content": {
              "application/json": {
                "schema": {
                  "oneOf": [
                    {
                      "type": "null"
                    },
                    {
                      "type": "integer"
                    },
                    {
                      "type": "string"
                    },
                    {
                      "type": "string",
                      "format": "date"
                    },
                    {}
                  ]
                }
              }
            }
          },
          "400": {
            "description": "Bad request syntax or unsupported method",
            "content": {
              "application/json": {
                "schema": {
                  "properties": {
                    "status_code": {
                      "type": "integer"
                    },
                    "detail": {
                      "type": "string"
                    },
                    "extra": {
                      "additionalProperties": {},
                      "type": [
                        "null",
                        "object",
                        "array"
                      ]
                    }
                  },
                  "type": "object",
                  "required": [
                    "detail",
                    "status_code"
                  ],
                  "description": "Validation Exception",
                  "examples": [
                    {
                      "status_code": 400,
                      "detail": "Bad Request",
                      "extra": {}
                    }
                  ]
                }
              }
            }
          }
        },
        "deprecated": false
      }
    }
  }
}

[nilsso]

@all-contributors please add @nilsso for code

[allcontributors]

@nilsso

I've put up a pull request to add @nilsso! 🎉