---
title: "Tmp File Upload Plugin"
description: "Stream large file uploads into temporary files instead of memory, so requests far larger than available memory are parsed safely."
sidebar:
  label: "Tmp File Upload"
---

## Installation

```package-install
npm install @orpc/node@beta
```

## Setup

Use `TmpFileUploadHandlerPlugin` to parse file uploads into temporary files. Bodies the standard parser would buffer into an in-memory [File](https://developer.mozilla.org/en-US/docs/Web/API/File), and [`multipart/form-data`](https://developer.mozilla.org/en-US/docs/Web/HTTP/Guides/MIME_types#multipartform-data) file parts, stream to disk instead. Every other body is left to the standard parser.

```ts
import { TmpFileUploadHandlerPlugin } from '@orpc/node'
import { RPCHandler } from '@orpc/server/node'

const handler = new RPCHandler(router, {
  plugins: [
    new TmpFileUploadHandlerPlugin({
      /**
       * The directory temporary files are created under. Each request that
       * spools an upload gets its own subdirectory inside it, removed when
       * the request finishes.
       *
       * @default os.tmpdir()
       */
      tmpDir: './uploads',
    }),
  ],
})
```

:::info
The `handler` can be any supported oRPC handler, such as [RPCHandler](/docs/rpc/handler), [OpenAPIHandler](/docs/openapi/handler), or a custom one.
:::

## Working with Uploaded Files

Procedures receive ordinary `File` instances and read them lazily from disk, in constant memory. Each one is a `TmpFile` exposing the `path` of its backing file, so an upload can be kept with a cheap [rename](https://nodejs.org/api/fs.html#fspromisesrenameoldpath-newpath) instead of a copy:

```ts
import { TmpFile } from '@orpc/node'
import { rename } from 'node:fs/promises'

const uploadVideo = os
  .input(z.object({ video: z.file() }))
  .handler(async ({ input }) => {
    if (input.video instanceof TmpFile) {
      await rename(input.video.path, `./videos/${crypto.randomUUID()}`)
    }
  })
```

:::warning
Temporary files are removed when the request finishes. A streaming response body, an event iterator or a raw stream, keeps them alive until it completes. Any other response is transmitted after removal, so a response that embeds the upload itself, as a `File` or inside `FormData`, needs the content copied or the file moved first. A moved or removed file can no longer be read through its `File` instance.
:::

## Limiting Body Sizes

Use `maxBodySize` to limit each kind of request body by what it actually costs. All three kinds are required together, so none is left unbounded by accident; set a kind to `Number.POSITIVE_INFINITY` to deliberately leave it unlimited. A body over its limit rejects with `PAYLOAD_TOO_LARGE`.

```ts
const handler = new RPCHandler(router, {
  plugins: [
    new TmpFileUploadHandlerPlugin({
      maxBodySize: {
        /**
         * Content parsed into memory: JSON, URL-encoded forms, and the
         * plain fields of a multipart body. Usually the lowest limit.
         */
        memory: 1024 * 1024,

        /**
         * Content streamed into temporary files: file bodies and the
         * file parts of a multipart body combined.
         */
        file: 10 * 1024 * 1024 * 1024,

        /**
         * Content consumed as a stream: event streams and raw binary
         * streams, enforced while the stream is consumed. Usually the
         * highest limit.
         */
        stream: Number.POSITIVE_INFINITY,
      },
    }),
  ],
})
```

A multipart body splits across the first two limits, fields against `memory` and file parts against `file`, and as a whole, framing included, it is bounded by the sum of both. A declared [Content-Length](https://developer.mozilla.org/en-US/docs/Web/HTTP/Reference/Headers/Content-Length) over the applicable limit rejects immediately, and enforcement continues while the body streams in, so a lying length cannot bypass it.

With all three limits configured, the plugin subsumes the [Request Limit Plugin](/docs/plugins/request-limit). When the [Request Compression Plugin](/docs/plugins/request-compression) is present, limits apply to the decompressed payload rather than the compressed wire size.

## Learn More

For implementation details, see the [source code](https://github.com/middleapi/orpc/blob/main/packages/node/src/tmp-file-upload-handler-plugin.ts).