How to return a complex JSON response with Node js

Question

Using nodejs and express  I d like to return one or multiple objects  array  using JSON  In the code below I output one JSON object at a time  It works but this isn t exactly what I want  The response produced isn t a valid JSON response since I have many objects    I am well aware that I could simply add all objects to an array and return that specific array in res end  However I am afraid this could become heavy to process and memory intensive    What is the proper way to acheive this with nodejs  Is query each the right method to call   app get   users  email messages unread   function req  res  next        var query   MessageInfo          find    and       email   req params email       hasBeenRead   false              res writeHead 200     Content-Type    application json             query each function err  msg            if  msg                 res write JSON stringify   msgId  msg fileName                else               res end

User · Accepted Answer

On express 3 you can use directly res json  foo bar    res json   msgId  msg fileName      See the documentation

User · Answer

I don t know if this is really any different  but rather than iterate over the query cursor  you could do something like this   query exec function  err  results     if  err  res writeHead 500  err message    else if   results length  res writeHead 404     else       res writeHead 200     Content-Type    application json          res write JSON stringify results map function  msg   return  msgId  msg fileName               res end

User · Answer

Edit  After reviewing the Mongoose documentation  it looks like you can send each query result as a separate chunk  the web server uses chunked transfer encoding by default so all you have to do is wrap an array around the items to make it a valid JSON object   Roughly  untested    app get   users  email messages unread   function req  res  next      var firstItem true  query MessageInfo find             res writeHead 200    Content-Type    application json       query each function docs           Start the JSON array or separate the next element      res write firstItem    firstItem false                  res write JSON stringify   msgId  msg fileName              res end          End the JSON array and response        Alternatively  as you mention  you can simply send the array contents as-is   In this case the response body will be buffered and sent immediately  which may consume a large amount of additional memory  above what is required to store the results themselves  for large result sets   For example          var query   MessageInfo find           res writeHead 200    Content-Type    application json     res end JSON stringify query map function x   return x fileName

[json] How to return a complex JSON response with Node.js?

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