I’ve already ready the other post(s) related to node http requests firing twice. I believe this is different.

I scripted a demo that uses a child process to read from a sqlite db and wired that functionality to an http request.

const { spawn } = require( 'node:child_process' )
const http = require( 'node:http' )

const queryDB = async ( query ) => {
  const child = spawn( 'sqlite3', [ 'some-sqlite3.db', query ] ) 
  return new Promise( resolve => {
    child.stdout.on( 'data', data => {
      resolve( data.toString() )
    } ) 
  } ) 
}

const server = http.createServer()
server.on( 'request', async ( req, res ) => {
  const url = new URL( req.url, 'http://' + req.headers.host )
  const queryStr = url.searchParams.get( 'q' )
  res.writeHead( 200, { 'Content-Type': 'text/plain' } ) 
  console.log( { queryStr }, new Date().toLocaleString() )
  res.write( await queryDB( queryStr ) ) 
  res.end( 'n' )
} )

server.listen( 3000, () => console.log( 'server live' ) ) 

I added a console.log to the http request handler to confirm the search param’s being parsed correctly but found the following when requesting http://localhost:3000/?q=pragma table_list either through browser or cURL

{ queryStr: 'pragma table_list' } 7/16/2024, 3:58:12 PM                                 
{ queryStr: null } 7/16/2024, 3:58:12 PM 

So it appears the request gets fired or handled twice and is not getting a query string the on the second event.

I rewrote queryDB to resolve after all data is received from the child process’ stdout but found it made no difference to the console output.

const queryDB = async ( query ) => {                                                                                  
  const child = spawn( 'sqlite3', [ 'bmc.db', query ] )                                                               
  return new Promise( resolve => {                                                                                    
    let response = ''                                                                                                 
                                                                                                                      
    child.stdout.on( 'data', data => {                                                                                
      response += data.toString()                                                                                     
    } )                                                                                                               
                                                                                                                      
    child.on( 'exit', () => {                                                                                         
      resolve( response )                                                                                             
    } )                                                                                                               
  } )                                                                                                                 
}

The http response I’m getting is exactly what I want but I would like some help understanding why the above is happening and how I can mitigate it.