5. Request Body¶

Body sources are mutually exclusive. You can use only one of Body, BodyStream, Form, or Multipart — specifying two or more fails with ProtocolError.

Typed JSON DTO¶

await client.Post("/games")
    .Body(new CreateGameReq("ranked-match-0611"))
    .Fetch<CreateGameRes>();

Unless a separate codec extension is registered, Body<T>(dto) serializes the DTO with the Web default (JsonSerializerDefaults.Web) and sets content-type: application/json. You don't need to register a codec per message type.

Raw Body¶

await client.Post("/raw").Body("plain text payload", "text/plain").AsyncRaw();

Form-Urlencoded¶

await client.Post("/login")
    .Form("user", "aria")
    .Form("password", "secret value")
    .AsyncRaw();
// content-type: application/x-www-form-urlencoded, percent-encoding applied

Multipart/Form-Data¶

await client.Post("/upload")
    .Multipart("title", "patch notes")
    .MultipartFile("file", "notes.txt", fileContent, "text/plain")
    .AsyncRaw();

Streaming Upload¶

BodyStream(provider, contentType) sends the body chunk by chunk with chunked transfer-encoding. The provider returns null when done. A streaming request can't be rewound, so it's excluded from automatic retry.

var chunks = new Queue<byte[]>(/* ... */);
await client.Post("/upload-stream")
    .BodyStream(
        () => chunks.Count > 0 ? chunks.Dequeue() : null,
        "application/octet-stream")
    .AsyncRaw();

The provider is a Func<byte[]?> — it returns null when done (being a reference type, ? chunk : null works cleanly).

Next: Handling Responses →