fastapi-xml 1.1.2

adds xml support to fastapi

FastAPI-XML

Seamless XML support for FastAPI — parse XML request bodies and return XML responses using standard Python dataclasses, with full OpenAPI integration.

pip install fastapi-xml

Built on xsdata for XML serialization, it slots into FastAPI the same way JSON does.

Features

• XML request bodies — replace Body() with XmlBody(), your endpoint receives a populated dataclass
• XML responses — return any dataclass and get back application/xml (or text/xml)
• OpenAPI schema — Swagger UI renders XML examples and schemas automatically
• Zero learning curve — works like FastAPI's JSON, just swap in XmlRoute and XmlBody
• Two media types — XmlAppResponse (application/xml) and XmlTextResponse (text/xml)

Quick Start

from dataclasses import dataclass, field
from fastapi import FastAPI
from fastapi_xml import XmlRoute, XmlAppResponse, XmlBody, add_openapi_extension

@dataclass
class HelloWorld:
    message: str = field(metadata={"type": "Element"})

app = FastAPI(title="FastAPI-XML", default_response_class=XmlAppResponse)
app.router.route_class = XmlRoute
add_openapi_extension(app)

@app.post("/echo", response_model=HelloWorld)
def echo(x: HelloWorld = XmlBody()) -> HelloWorld:
    x.message += " Forever!"
    return x

<!-- Request -->
<HelloWorld><message>Hello</message></HelloWorld>

<!-- Response -->
<HelloWorld><message>Hello Forever!</message></HelloWorld>

How It Works

XmlRoute replaces FastAPI's default APIRoute. When a request arrives with an XML body, the XmlDecoder (wrapping xsdata's XmlParser) deserializes it into your dataclass. On the way out, XmlResponse serializes the return value back to XML via xsdata's XmlSerializer.

Response Types

Class	Content-Type
XmlAppResponse	application/xml
XmlTextResponse	text/xml

OpenAPI

Call add_openapi_extension(app) to generate accurate XML schemas in your OpenAPI spec. The Swagger UI at /docs will show XML examples and let you test endpoints directly.

Example

from dataclasses import dataclass, field
from fastapi import FastAPI
from fastapi_xml import XmlRoute, XmlAppResponse, XmlBody


@dataclass
class Item:
    name: str = field(metadata={"type": "Element"})
    price: float = field(metadata={"type": "Element"})

@dataclass
class Order:
    id: str = field(metadata={"type": "Element"})
    items: list[Item] = field(metadata={"type": "Element", "name": "Item"})


app = FastAPI(default_response_class=XmlAppResponse)
app.router.route_class = XmlRoute


@app.post("/order", response_model=Order)
def create_order(order: Order = XmlBody()) -> Order:
    return order


if __name__ == "__main__":
    import uvicorn
    uvicorn.run(app)

API

Symbol	Description
XmlBody()	Mark a parameter as coming from XML body
XmlRoute	Route class that enables XML handling
XmlAppResponse	Response class for application/xml
XmlTextResponse	Response class for text/xml
add_openapi_extension	Patches OpenAPI schema for XML types

Requirements

• Python 3.10+
• FastAPI >= 0.113.0
• xsdata >= 22.9

License

MIT