Declare request example for PlainTextResponse

[bjhulst]

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

PlainTextResponse

Description

Could you add to this page https://github.com/tiangolo/fastapi/blob/master/docs/en/docs/tutorial/schema-extra-example.md (or create a new page) an example of how the PlainTextResponse example value could be written in the fastapi Python code?

All it says now is "string"..... :-)

Maybe due to a lack of a schema...but a placeholder for the actual value of the string would be usefull to know about.

Wanted Solution

Tutorial documentation update.

Wanted Code

n/a

Alternatives

No response

Operating System

Other

Operating System Details

No response

FastAPI Version

latest

Python Version

3.9

Additional Context

No response

[aovasylenko]

I was playing a bit with source code and in case of small changes in openapi generation utilities, and using next code:

from fastapi import FastAPI
from fastapi.responses import PlainTextResponse
from pydantic import BaseModel


app = FastAPI()


class HelloWorld(BaseModel):
    __root__: str

    class Config:
        schema_extra = {"example": "Hello World"}


@app.get("/", response_class=PlainTextResponse, response_model=HelloWorld)
async def main():
    return "Hello World"

I've received next specification:

openapi: 3.0.2
info:
  title: FastAPI
  version: 0.1.0
paths:
  /:
    get:
      summary: Main
      operationId: main__get
      responses:
        '200':
          description: Successful Response
          content:
            text/plain:
              schema:
                $ref: '#/components/schemas/HelloWorld'
components:
  schemas:
    HelloWorld:
      example: Hello World
      title: HelloWorld
      type: string

Is it what expected? (you can paste it into https://editor.swagger.io/ to check the output in UI)