validation_error_definition schema is incorrect when detecting an error in an array #3790
Description
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 typing import Optional, List
from fastapi import FastAPI
from pydantic import BaseModel
class SubItem(BaseModel):
price: float
class Item(BaseModel):
price_list: Optional[List[SubItem]] = None
app = FastAPI()
@app.post("/items/")
async def create_item(item: Item):
return itemDescription
Run the sample program and call the /items/ api with this body:
{
"price_list": [
{
"price": "zero"
}
]
}
You will get a 422 like this
{
"detail": [
{
"loc": [
"body",
"price_list",
0,
"price"
],
"msg": "value is not a valid float",
"type": "type_error.float"
}
]
}
But this 422 response does not follow the validation_error_definition schema :
validation_error_definition = {
"title": "ValidationError",
"type": "object",
"properties": {
"loc": {"title": "Location", "type": "array", "items": {"type": "string"}},
"msg": {"title": "Message", "type": "string"},
"type": {"title": "Error Type", "type": "string"},
},
"required": ["loc", "msg", "type"],
}
So the 422 response from fastapi does not respect the schema of the response...
The issue comes from the error in the array, pydantic returns 0 as index of the error, but it is not a string, it is an integer. And it makes sense to return an integer, otherwise we wouldn't know if it is a key in a dict or an index.
As a developer I can workaround this issue by redefining validation_error_definition in my own code
from fastapi.openapi.utils import validation_error_definition
validation_error_definition["properties"] = {
"loc": {
"title": "Location", "type": "array", "items": {
"oneOf": [
{"type": "string"},
{"type": "integer"}
]
}
},
"msg": {"title": "Message", "type": "string"},
"type": {"title": "Error Type", "type": "string"},
}
But it would be better to do the change directly in the code. What is your opinion ?
Operating System
Windows
Operating System Details
No response
FastAPI Version
0.68.1
Python Version
3.7.9
Additional Context
No response