form-parser

Description

A streaming and asynchronous multipart/form-data parser.

Install

npm install form-parser --save

Examples

Using micro:

// Dependencies
const parser = require('form-parser')
const { send } = require('micro')
 
// Create server
module.exports = async (req, res) => {
  // Parse request
  await parser(req, async field => {
    // Log info
    console.log(field) // { fieldType, fieldName, fieldContent }
  })
 
  // Reply with finished
  return send(res, 200, 'Parsing form succeded.')
}

Native HTTP server:

// Dependencies
const http = require('http')
const parser = require('form-parser')
 
// Create server
const server = http.createServer(async (req, res) => {
  // Wrap in try/catch block
  try {
    // Parse request
    await parser(req, async field => {
      // Log info
      console.log(field) // { fieldType, fieldName, fieldContent }
    })
  
  // Catch errors
  } catch (err) {
    // Log error
    console.error(err)
 
    // Reply with error
    res.statusCode = 400
    return res.end('Something went wrong.')
  }
 
  // Reply with success
  return res.end('Parsing form succeded.')
})
 
// Start server
server.listen(3000, () => {
  console.log('Listening on port 3000...')
})

Streaming file upload:

// Dependencies
const http = require('http')
const parser = require('form-parser')
const path = require('path')
const fs = require('fs')
 
// Create server
const server = http.createServer(async (req, res) => {
  try {
    // Parse request
    await parser(req, async field => {
      // Get info
      const { fieldType, fieldName, fieldContent } = field
      
      // Only handle files
      if (fieldType !== 'file') {
        return
      }
 
      // Get file info
      const { fileName, fileType, fileStream } = fieldContent
 
      // Prepare write stream
      const writeFilePath = path.resolve(__dirname, 'files', fileName)
      const writeFileStream = fs.createWriteStream(writeFilePath)
 
      // Write file to disk
      await new Promise((resolve, reject) => {
        fileStream.pipe(writeFileStream).on('error', reject).on('finish', resolve)
      })
 
      // Log info
      console.log(`${fileName} has been written to disk.`)
    })
  
  // Catch errors
  } catch (err) {
    // Log error
    console.error(err)
 
    // Reply with error
    res.statusCode = 400
    return res.end('Something went wrong.')
  }
 
  // Reply with success
  return res.end('Parsing form succeded.')
})
 
// Start server
server.listen(3000, () => {
  console.log('Listening on port 3000...')
})

API

parser(req, callback)

The parser() function is a top-level function exported by the form-parser module.

• req HTTP request object.
• callback(field => {}) An Async function, that's called for each new form field found. Passes field as argument.

field Is an object containing the following keys:

• fieldType The field type (one of 'text' or 'file').
• fieldName The field name.
• fieldContent The field content.
  • If fieldType is 'text', fieldContent will contain the field text value.
  • If fieldType is 'file', fieldContent will contain an object with the following keys:
    • fileName The name of the file.
    • fileType The mime type of the file.
    • fileStream The file stream (ReadableStream).