Request limits and bodies

Flare enforces body size limits and chooses buffering versus streaming based on your contract descriptor. Oversized bodies return 413 ContentTooLarge. Malformed JSON returns 400.

Global default

The global cap is host.maxBodyBytes in flare.json (default 2 MiB). See flare.json reference.

{
  "host": {
    "maxBodyBytes": 2097152
  }
}

Override at runtime: FLARE__HOST__MAXBODYBYTES=4194304.

Per-route override

Add maxBodyBytes on the route descriptor (inline field or httpContract entry):

import { httpContract } from "@flare-ts/core";
import { model, str } from "@flare-ts/lib/schema";

class FeedbackBody extends model({ message: str.min(1) }) {}

const FeedbackContract = httpContract({
  submit: {
    body: FeedbackBody,
    maxBodyBytes: 51200,
  },
});

Bodies over the limit return 413 with { error: "ContentTooLarge", code: 413, detail: { maxBytes } }.

JSON bodies

When the descriptor declares a body schema or model(), Flare buffers and validates JSON after before middleware. Read the result from scope.input.body (inline) or ctx.extract(entry).body (controller). An empty or missing JSON body becomes null.

Streaming bodies

Declare body: stream (import stream from @flare-ts/core) to skip JSON buffering. The inbound stream attaches before before middleware runs.

import { FlareHost, FlareResponse, stream } from "@flare-ts/core";
import { node } from "@flare-ts/core/node";

const host = new FlareHost(node);

host.http.post("/upload", { body: stream, maxBodyBytes: 50 * 1024 * 1024 }, async (ctx) => {
  let bytes = 0;
  for await (const chunk of ctx.req.stream()) {
    bytes += chunk.byteLength;
  }
  return new FlareResponse(200, { bytes });
});

const app = host.build();
app.run();

Size is enforced while iterating chunks, not only up front.

One read strategy per request. stream() throws if buffer(), text(), or json() already started.

Manual body readers

Without a body in the descriptor, Flare does not parse JSON. Use ctx.req.buffer(), text(), json(), or stream() directly. See Requests.

Validation failures

Input	Status	Body shape
Route params	400	Invalid route parameters message
Query string	400	Invalid query parameters message
JSON body (schema failure)	400	{ error, details: [ field errors ] }
Body too large	413	ContentTooLarge with maxBytes

These bypass host.http.error().

Related

• Streaming bodies
• HTTP contracts
• Failure modes