File Uploads

IFormFile parameters are detected automatically. The generated client constructs FormData and lets the browser set the correct Content-Type with multipart boundary.

Example

[RivetEndpoint]
[HttpPost("{id:guid}/attachments")]
[ProducesResponseType(typeof(AttachmentResultDto), StatusCodes.Status201Created)]
public async Task<IActionResult> Attach(Guid id, IFormFile file, CancellationToken ct)
{
    return StatusCode(StatusCodes.Status201Created,
        new AttachmentResultDto(Guid.NewGuid(), file.FileName, file.Length));
}

// Generated — File parameter, FormData construction handled automatically
export function attach(id: string, file: File): Promise<AttachmentResultDto>;
export function attach(id: string, file: File, opts: { unwrap: false }): Promise<RivetResult<AttachmentResultDto>>;
export async function attach(id: string, file: File, opts?: { unwrap?: boolean }) {
  const fd = new FormData();
  fd.append("file", file);
  return rivetFetch("POST", `/api/tasks/${id}/attachments`, { body: fd, unwrap: opts?.unwrap });
}

IFormFile in contract records

IFormFile is a mapped scalar type in Rivet. You can use it as a property in [RivetType] records for multipart upload contracts:

[RivetType]
public sealed record UploadInput(IFormFile Document, string Title);

[RivetContract]
public static class FilesContract
{
    public static readonly RouteDefinition<UploadInput, UploadResult> Upload =
        Define.Post<UploadInput, UploadResult>("/api/files")
            .AcceptsFile();
}

The emitter produces a multipart/form-data request body with $ref to the component schema. File properties are marked with format: binary and x-rivet-file: true.

Limitations

• Single file only — IFormFileCollection and List<IFormFile> are not supported
• The parameter must be typed as IFormFile