title: Custom Response Classes
description: Use HTML, streaming, file, and other custom response types in JustAPI.
keywords: [JustAPI, custom response, HTML, streaming, file response, redirect, response_class]

Using response_class in Decorator

Set the response class directly in the decorator:

from starlette.responses import HTMLResponse, PlainTextResponse
from justapi import JustAPIApp

app = JustAPIApp()

@app.get("/", response_class=PlainTextResponse)
def root():
    return "Hello, plain text!"

This also documents the correct Content-Type in the OpenAPI schema.

HTML Response

@app.get("/html")
def html_page():
    return HTMLResponse(content="<h1>Hello</h1><p>This is HTML</p>")

Or using response_class:

@app.get("/html", response_class=HTMLResponse)
def html_page():
    return "<h1>Hello</h1>"

Streaming Response

from starlette.responses import StreamingResponse
import asyncio

async def generate_tokens():
    for i in range(10):
        yield f"data: token_{i}\n\n"
        await asyncio.sleep(0.1)

@app.get("/stream")
def stream():
    return StreamingResponse(generate_tokens(), media_type="text/event-stream")

Redirect

from starlette.responses import RedirectResponse

@app.get("/old-path")
def old_path():
    return RedirectResponse(url="/new-path", status_code=302)

@app.get("/new-path")
def new_path():
    return {"message": "you are here"}

Or using response_class:

@app.get("/old-path", response_class=RedirectResponse, status_code=302)
def old_path():
    return "/new-path"

File Response

from starlette.responses import FileResponse

@app.get("/download")
def download():
    return FileResponse("report.pdf", filename="report.pdf")

JSON Response with Custom Headers

from starlette.responses import JSONResponse

@app.get("/custom")
def custom():
    return JSONResponse(
        content={"data": "value"},
        headers={"X-Custom": "header-value"},
    )

Plain Text Response

@app.get("/text")
def text():
    return PlainTextResponse("Hello, plain text!")

Default Response Class

Set a default response class for all routes:

from starlette.responses import ORJSONResponse

app = JustAPIApp(default_response_class=ORJSONResponse)

:::tip
ORJSONResponse is faster than JSONResponse for large payloads. Install with pip install orjson.
:::

Custom Response Class

Create your own response class:

from starlette.responses import JSONResponse

class PrettyJSONResponse(JSONResponse):
    def render(self, content) -> bytes:
        import json
        return json.dumps(
            content,
            indent=2,
            ensure_ascii=False,
        ).encode("utf-8")

@app.get("/pretty")
def pretty():
    return PrettyJSONResponse(content={"data": "value"})

Response Class + Status Code

Combine response_class with status_code:

@app.post("/items", response_class=JSONResponse, status_code=201)
def create_item():
    return {"message": "created"}

See Also

• Return a Response Directly — basic response object usage
• Streaming Output — JustAPI-native streaming
• Static Files — serving files