Mashumaro instead of Pydantic

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.
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• I already checked if it is not related to FastAPI but to Pydantic.
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Commit to Help

• I commit to help with one of those options 👆

Example Code

from dataclasses import dataclass
from typing import Optional

from fastapi import FastAPI
from mashumaro import DataClassJSONMixin

app = FastAPI()


@dataclass
class Item(DataClassJSONMixin):
    name: str
    price: float
    is_offer: Optional[bool] = None


@app.get("/")
def read_root():
    return {"Hello": "World"}


@app.get("/items/{item_id}")
def read_item(item_id: int, q: Optional[str] = None):
    return {"item_id": item_id, "q": q}


@app.put("/items/{item_id}")
def update_item(item_id: int, item: Item):
    return {"item_name": item.name, "item_id": item_id}

Description

pydantic can be a bit on the slower side and the default functionality is not geared towards strict typing. "1" can become 1 in an int() field. I don’t think this is good behavior for APIs. Also, mypy only catches pydantic issues with a plugin. Which does work well, but it is a bit unusual in my mind.

https://github.com/Fatal1ty/mashumaro looks like it provides the needed functionality, but with speed benefits and strictness.

I know it’d be a huge change, or maybe mashumaro could be supported in addition. In the past I’ve liked dacite, but it looks like mashumaro might be even better.

Just to note that as it is, dataclasses in FastAPI are very limited and buggy.

Wanted Solution

Being able to use mashumaro classes in FastAPI.

Wanted Code

from dataclasses import dataclass
from typing import Optional

from fastapi import FastAPI
from mashumaro import DataClassJSONMixin

app = FastAPI()


@dataclass
class Item(DataClassJSONMixin):
    name: str
    price: float
    is_offer: Optional[bool] = None


@app.get("/")
def read_root():
    return {"Hello": "World"}


@app.get("/items/{item_id}")
def read_item(item_id: int, q: Optional[str] = None):
    return {"item_id": item_id, "q": q}


@app.put("/items/{item_id}")
def update_item(item_id: int, item: Item):
    return {"item_name": item.name, "item_id": item_id}

Alternatives

dacite

Operating System

Linux

Operating System Details

No response

FastAPI Version

0.68.1

Python Version

3.8.10

Additional Context

Thank you!

[c00kiemon5ter]

apischema actually looks very good!

[kevinheavey]

One key feature that Pydantic has, that most of the other libraries are missing as far as I can tell, is JSON schema support and related types (e.g. constr(regex=...) correctly translates to the pattern JSON schema field), which is required in order for FastAPI to generate OpenAPI schemas.

Just chiming in to add that apischema supports this.