Express js req body undefined

Question

I have this as configuration of my Express server  app use app router    app use express cookieParser     app use express session   secret   keyboard cat       app set  view engine    ejs    app set  view options     layout  true       Handles post requests app use express bodyParser       Handles put requests app use express methodOverride       But still when I ask for req body something in my routes I get some error pointing out that body is undefined  Here is an example of a route that uses req body    app post   admin   function req  res       console log req body name         I read that this problem is caused by the lack of app use express bodyParser     but as you can see I call it before the routes   Any clue

User · Answer

Mine was a text input and I m adding this answer here regardless so it would help people  Make sure your encoding is set when parsing  I struggled to make it work until I set a proper value to it   This was the error I was getting without using any parser    error info  TypeError  ERR INVALID ARG TYPE   The first argument must be of type string or an instance of Buffer  ArrayBuffer  or Array or an Array-like Object   Received an instance of undefined at Function from  buffer js 327 9    We do not have to use body-parser now in Express as others have already mentioned  but just that app use express text     did not solve my issue   undefined now changed to Object  According to Express documentation  request body returns an empty object      if Content-Type doesn t match  among others    error info  TypeError  ERR INVALID ARG TYPE   The first argument must be of type string or an instance of Buffer  ArrayBuffer  or Array or an Array-like Object   Received an instance of Object at Function from  buffer js 327 9    The encoding type you set needs to be on point as well  In my case  it was text plain  You can change it to suit your needs like JSON  etc  I did this and voila  Worked like a charm   app use express text       type   text plain

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Most of the time req body is undefined due to missing JSON parser  const express   require  express    app use express json       could be missing for the body-parser  const bodyParser    require  body-parser    app use bodyParser urlencoded  extended  true       and sometimes it s undefined due to cros origin so add them  const cors   require  cors    app use cors

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In my case  it was because of using body-parser after including the routes   The correct code should be  app use bodyParser urlencoded  extended true     app use methodOverride   method     app use indexRoutes   app use userRoutes   app use adminRoutes

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Simple example to get through all  Express Code For Method  post  after Login  This would not require any such bodyParser     app js const express   require  express    const mongoose   require  mongoose    const mongoDB   require  mongodb     const app   express     app set  view engine    ejs     app get   admin    req res    gt     res render  admin         app post   admin    req res    gt     console log JSON stringify req body name     res send JSON stringify req body name         app listen 3000       gt     console log  listening on 3000         admin ejs  lt  DOCTYPE Html gt   lt html gt    lt head gt     lt title gt Admin Login lt  title gt    lt  head gt    lt body gt      lt div gt       lt center padding  quot 100px quot  gt          lt form method  quot post quot  action  quot  admin quot  gt             lt div gt  Secret Key               lt input name  name  gt  lt  input gt             lt  div gt  lt br gt  lt  br gt  lt br gt  lt  br gt             lt div gt               lt button type  quot submit quot  onClick  smsAPI    gt Get OTP lt  button gt             lt  div gt          lt  form gt       lt  center gt       lt  div  gt   lt  body gt   lt  html gt   You get input  The  name  in  quot  quot  is a variable that carries data through method  post   For multiple data input  name  name     Hence  on name  name    input  Adu backend   quot Adu quot   OR  input  Adu  Luv  backend   quot Adu  Luv  quot   on name  name    input  Adu 45689  ugghb  Luv backend    quot Adu 45689  ugghb  Luv quot

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This is also one possibility  Make Sure that you should write this code before the route in your app js or index js  file   app use bodyParser urlencoded   extended  true      app use bodyParser json

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The Content-Type in request header is really important  especially when you post the data from curl or any other tools   Make sure you re using some thing like application x-www-form-urlencoded  application json or others  it depends on your post data  Leave this field empty will confuse Express

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UPDATE July 2020 express bodyParser   is no longer bundled as part of express  You need to install it separately before loading  npm i body-parser     then in your app var express   require  express   var bodyParser   require  body-parser     var app   express        create application json parser var jsonParser   bodyParser json        create application x-www-form-urlencoded parser var urlencodedParser   bodyParser urlencoded   extended  false         POST  login gets urlencoded bodies app post   login   urlencodedParser  function  req  res      res send  welcome      req body username          POST  api users gets JSON bodies app post   api users   jsonParser  function  req  res         create user in req body     See here for further info original follows You must make sure that you define all configurations BEFORE defining routes  If you do so  you can continue to use express bodyParser    An example is as follows  var express   require  express        app       express        port      parseInt process env PORT  10     8080   app configure function      app use express bodyParser       app use app router        app listen port        app post  quot  someRoute quot   function req  res      console log req body     res send   status   SUCCESS

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You can try adding this line of code at the top   after your require statements    app use bodyParser urlencoded  extended  true       As for the reasons as to why it works  check out the docs  https   www npmjs com package body-parser bodyparserurlencodedoptions

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This occured to me today  None of above solutions work for me  But a little googling helped me to solve this issue  I m coding for wechat 3rd party server   Things get slightly more complicated when your node js application requires reading streaming POST data  such as a request from a REST client  In this case  the request s property  readable  will be set to true and the POST data must be read in chunks in order to collect all content    http   www primaryobjects com CMS Article144

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First make sure   you have installed npm module named  body-parser  by calling    npm install body-parser --save   Then make sure you have included following lines before calling routes  var express   require  express    var bodyParser   require  body-parser    var app   express     app use bodyParser json

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For anyone who none of the answers above have worked for I had to enable cors between my front-end and express     You can do this either by    Downloading and turning on a CORS extension for your browser  such as   https   chrome google com webstore detail allow-control-allow-origi nlfbmbojpeacfghkpbjhddihlkkiljbi hl en   for Chrome       or by   Adding the lines  var cors require  cors     app use cors        to your express app js page   After npm install cors

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The middleware is always used as first    MIDDLEWARE app use bodyParser json     app use cors         app use cookieParser      before the routes    MY ROUTES app use  quot  api quot   authRoutes

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adding express urlencoded   extended  true    to the route solves the problem    router post   save  express urlencoded   extended  true       your route

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You can use express body parser   var express   require  express    var app   express    var bodyParser   require  body-parser    app use bodyParser urlencoded   extended  true

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Express 4  has build-in body parser  No need to install separate body-parser  So below will work   export const app   express    app use express json

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Latest versions of Express  4 x  has unbundled the middleware from the core framework  If you need body parser  you need to install it separately  npm install body-parser --save   and then do this in your code  var bodyParser   require  body-parser   var app   express       parse application x-www-form-urlencoded app use bodyParser urlencoded   extended  false         parse application json app use bodyParser json

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app use express json      It will help to solve the issue of req body undefine

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This issue may be because you have not use body-parser  link   var express   require  express    var bodyParser    require  body-parser     var app   express    app use bodyParser json

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express bodyParser   needs to be told what type of content it is that it s parsing  Therefore  you need to make sure that when you re executing a POST request  that you re including the  Content-Type  header  Otherwise  bodyParser may not know what to do with the body of your POST request   If you re using curl to execute a POST request containing some JSON object in the body  it would look something like this   curl -X POST -H  Content-Type  application json  -d  your json file http   localhost xxxx someRoute   If using another method  just be sure to set that header field using whatever convention is appropriate

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Okay This may sound Dumb but it worked for me  as a total beginner  I didn t realized that writing  router post  quot   quot    res  req    gt      console log req body     req send  quot User Route quot         is wrong   You have make sure that you pass parameters req res  of post get in right order  and call them accordingly  router post  quot   quot    req  res    gt      console log req body     res send  quot User Route quot

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Wasted a lot of time   Depending on Content-Type in your client request the server should have different  one of the below app use       app use bodyParser text   type   text html      app use bodyParser text   type   text xml      app use bodyParser raw   type   application vnd custom-type      app use bodyParser json   type   application   json        Source  https   www npmjs com package body-parser bodyparsertextoptions  Example   For me  On Client side  I had below header   Content-Type   text xml    So  on the server side  I used   app use bodyParser text  type   text xml        Then  req body worked fine

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Require body-parser  to receive post data from clients   var bodyParser   require  body-parser     app use bodyParser urlencoded   extended  false         parse application json  app use bodyParser json

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Credit to  spikeyang for the great answer  provided below   After reading the suggested article attached to the post  I decided to share my solution   When to use   The solution required you to use the express router in order to enjoy it   so   If you have you tried to use the accepted answer with no luck  just use copy-and-paste this function   function bodyParse req  ready  fail         var length   req header  Content-Length         if   req readable  return fail  failed to read request         if   length  return fail  request must include a valid  Content-Length  header         if  length  gt  1000  return fail  this request is too big       you can replace 1000 with any other value as desired      var body          for large payloads - please use an array buffer  see note below       req on  data   function  data                 body    data                req on  end   function                   ready body               and call it like   bodyParse req  function success body        function error message           NOTE   For large payloads - please use an array buffer  more   MDN

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Latest version of Express already has body-parser built-in  So you can use   const express   require  express        app use express urlencoded   extended  false      use express json

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Building on  kevin-xue said  the content type needs to be declared  In my instance  this was only occurring with IE9 because the XDomainRequest doesn t set a content-type  so bodyparser and expressjs were ignoring the body of the request    I got around this by setting the content-type explicitly before passing the request through to body parser  like so   app use function req  res  next           IE9 doesn t set headers for cross-domain ajax requests     if typeof req headers  content-type         undefined            req headers  content-type      application json  charset UTF-8             next        use bodyParser json

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As already posted under one comment  I solved it using   app use require  connect   bodyParser       instead of   app use express bodyParser       I still don t know why the simple express bodyParser   is not working

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I solved it with   app post      bodyParser json     req  res    gt     we have req body JSON

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No  You need to use app use express bodyParser    before app use app router   In fact  app use app router  should be the last thing you call

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in Express 4  it s really simple  const app   express   const p   process env PORT    8082  app use express json

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In case anyone runs into the same issue I was having  I am using a url prefix like  http   example com api    which was setup with router  app use   api   router      and then I had the following  app use bodyParser json     app use bodyParser urlencoded   extended  true        What fixed my issue was placing the bodyparser configuration above app use   api   router    Final      setup bodyparser     app use bodyParser json         app use bodyParser urlencoded   extended  true         this is a fix for the prefix of example com api  so we dont need to code the prefix in every route     app use   api   router

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In case if you post SOAP message you need to use raw body parser   var express   require  express    var app   express    var bodyParser   require  body-parser     app use bodyParser raw   type   text xml

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If you are using some external tool to make the request  make sure to add the header   Content-Type  application json

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Another possible way to get empty request body when you forget the name attribute from  the input element      lt input type  text    gt     give back empty request body - gt        lt input type  text  name  username    gt     give back request body - gt    username    your-input

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var bodyParser   require  body-parser    app use bodyParser json       This saved my day

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To work  you need to app use app router  after app use express bodyParser     like that   app use express bodyParser        use express methodOverride        use app router

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Use app use bodyparser json     before routing       app use   api   routes

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Add in your app js  before the call of the Router   const app   express    app use express json

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Looks like the body-parser is no longer shipped with express  We may have to install it separately    var express      require  express   var bodyParser   require  body-parser   var app   express       parse application x-www-form-urlencoded app use bodyParser urlencoded   extended  false         parse application json app use bodyParser json        parse application vnd api json as json app use bodyParser json   type   application vnd api json      app use function  req  res  next    console log req body     populated    Refer to the git page https   github com expressjs body-parser for more info and examples

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