Query param of type UUID is presented as array[string] instead of array[string($uuid)] when capturing lists

[josecsotomorales]

First Check

• I added a very descriptive title to this issue.
• I used the GitHub search to find a similar issue and didn't find it.
• I searched the FastAPI documentation, with the integrated search.
• I already searched in Google "How to X in FastAPI" and didn't find any information.
• I already read and followed all the tutorial in the docs and didn't find an answer.
• I already checked if it is not related to FastAPI but to Pydantic.
• I already checked if it is not related to FastAPI but to Swagger UI.
• I already checked if it is not related to FastAPI but to ReDoc.

Commit to Help

• I commit to help with one of those options 👆

Example Code

from fastapi import FastAPI

app = FastAPI()

@app.get("/test")
def get_query_params(
                  field_1: Optional[UUID] = None, # type on swagger: string($uuid) - OK
                  field_2: Optional[List[str]] = Query(None), # type on swagger: array[string] - OK
                  field_3: Optional[List[UUID]] = Query(None) # type on swagger: array[string] - NOT OK, Pydantic still validates it as an uuid.
                  ):
    return {"Hello", "World"}

Description

Open the browser and navigate to swagger docs on http://localhost:8000/docs, then go to the endpoint parameter types, which should be enough to reproduce this issue.

Operating System

macOS

Operating System Details

No response

FastAPI Version

0.70.1

Python Version

3.9.9

Additional Context

No response

[ugtar]

it appears to be a purely cosmetic issue in swagger ui, not a fastapi bug. I created a similar setup

from typing import Optional, List
import uuid

from fastapi import FastAPI, Query


app = FastAPI()


@app.get("/")
async def root(
    field0: Optional[uuid.UUID] = None,
    field: Optional[List[uuid.UUID]] = Query(default=None)
):
    return {"message": "Hello World"}

The corresponding swagger ui looks like this

as you said the description in swagger ui for the list is array[string] not array[string($uuid)], but the field is validated properly as a uuid in swagger ui

as well as correctly validated by pydantic

curl -X 'GET'   'http://127.0.0.1:8000/?field=3fa85f64-5717-4562-b3fc-2c963f66afa&field=1d27e9ac-238c-4a8b-b988-b7f5d2471318'   -H 'accept: application/json'
{"detail":[{"loc":["query","field",0],"msg":"value is not a valid uuid","type":"type_error.uuid"}]}

The openapi also appears correct

  "paths": {
    "/": {
      "get": {
        "summary": "Root",
        "operationId": "root__get",
        "parameters": [
          {
            "required": false,
            "schema": {
              "title": "Field0",
              "type": "string",
              "format": "uuid"
            },
            "name": "field0",
            "in": "query"
          },
          {
            "required": false,
            "schema": {
              "title": "Field",
              "type": "array",
              "items": {
                "type": "string",
                "format": "uuid"
              }
            },
            "name": "field",
            "in": "query"
          }
        ],

You can see each item is type: string and format: uuid.

So this looks like a cosmetic issue in swagger ui, not a behavior issue in either swagger or fastapi.

[josecsotomorales]

@ugtar thanks for your response! you are correct! it all works as expected, validation, formatting etc, seems to be purely visual from swagger docs, closing this issue.

[ugtar]

...but you might still open an issue on https://github.com/swagger-api/swagger-ui