Efficient Multipart Data Handling in Minima.js

The @minimajs/multipart package provides a simple, context-aware API for handling multipart form data, including file uploads.

Installation:

npm install @minimajs/multipart

Targeted File Access: multipart.file()

Retrieves a single file from the request. If a field name is provided, it gets that specific file; otherwise, it resolves with the first file found.

import { multipart } from "@minimajs/multipart";

async function handleFile() {
  // Get the first file in the request
  const anyFile = await multipart.file();

  // Get a file from a specific field
  const avatar = await multipart.file("avatar");

  if (avatar) {
    const fileBuffer = await avatar.buffer();
    // Process the file buffer...
  }
}

Iterate Over Multiple Files: multipart.files()

Provides an asynchronous iterator that yields each uploaded File object sequentially, ignoring non-file fields.

import { multipart } from "@minimajs/multipart";
import { pipeline } from "stream/promises";
import { createWriteStream } from "fs";

async function handleMultipleFiles() {
  for await (const file of multipart.files()) {
    console.log(`Saving file: ${file.filename}`);
    await pipeline(file.stream, createWriteStream(file.filename));
  }
}

Retrieve Form Fields: multipart.fields()

Returns a promise that resolves to a Record<string, unknown>, providing access to all non-file form fields and their corresponding values.

import { multipart } from "@minimajs/multipart";

async function handleFormFields() {
  const formData = await multipart.fields();
  const username = formData.username as string;
  const email = formData.email as string;
  // Process form data...
}

Process All Parts: multipart()

Returns an asynchronous iterator that yields a tuple [fieldName, value] for every part in the request body. The value can be a string for text fields or a File object for file uploads. This offers maximum flexibility.

import { multipart, isFile } from "@minimajs/multipart";

async function handleRequestBody() {
  for await (const [fieldName, value] of multipart()) {
    if (isFile(value)) {
      console.log(`File uploaded in field ${fieldName}: ${value.filename}`);
      // Handle file upload...
    } else {
      console.log(`Field: ${fieldName}, Value: ${value}`);
    }
  }
}

The File Class

This class encapsulates the information and functionality related to an uploaded file.

• Properties:

  • field: The name of the form field for the file.
  • filename: The original filename.
  • encoding: The character encoding of the file.
  • mimeType: The MIME type of the file.
  • stream: A Readable stream of the file content.

• Methods:

  • buffer(): Reads the entire file content into a buffer.
  • move(dir, filename): Moves the uploaded file to a specified directory.
  • flush(): Discards the remaining content of the stream.

The isFile Function

A type guard function to check if a given object is an instance of the File class.

import { isFile } from "@minimajs/multipart";

if (isFile(someValue)) {
  // someValue is now typed as File
  console.log(someValue.filename);
}