How do I redirect in expressjs while passing some context

Question

I am using express to make a web app in node js  This is a simplification of what I have   var express   require  express    var jade   require  jade    var http   require  http      var app   express    var server   http createServer app    app get      function req  res           Prepare the context     res render  home jade   context        app post   category   function req  res           Process the data received in req body     res redirect             My problem is the following   If I find that the data sent in  category doesn t validate  I would like pass some additional context to the   page  How could I do this  Redirect doesn t seem to allow any kind of extra parameter

User · Answer

I use a very simple but efficient technique in my app.js ( my entry point ) I define a variable like

let authUser = {};

Then I assign to it from my route page ( like after successful login )

authUser = matchedUser

It May be not the best approach but it fits my needs.

User · Answer

we can use express-session to send the required data  when you initialise the app  const express   require  express    const app   express    const session   require  express-session    app use session  secret   mySecret   resave  false  saveUninitialized  false       so before redirection just save the context for the session  app post   category   function req  res           add your context here  req session context   your context here        res redirect             Now you can get the context anywhere for the session  it can get just by req session context  app get      function req  res            So prepare the context var context req session context      res render  home jade   context

User · Answer

use app set  amp  app get  Setting data  router get      facebook callback     passport authenticate  facebook       req  res    gt        req app set  user   res req user      return res redirect   sign             Getting data  router get   sign    req  res    gt      console log  sign   req app get  user

User · Answer

I had to find another solution because none of the provided solutions actually met my requirements  for the following reasons    Query strings  You may not want to use query strings because the URLs could be shared by your users  and sometimes the query parameters do not make sense for a different user  For example  an error such as  error sessionExpired should never be displayed to another user by accident  req session  You may not want to use req session because you need the express-session dependency for this  which includes setting up a session store  such as MongoDB   which you may not need at all  or maybe you are already using a custom session store solution  next    You may not want to use next   or next  router   because this essentially just renders your new page under the original URL  it s not really a redirect to the new URL  more like a forward rewrite  which may not be acceptable    So this is my fourth solution that doesn t suffer from any of the previous issues  Basically it involves using a temporary cookie  for which you will have to first install cookie-parser  Obviously this means it will only work where cookies are enabled  and with a limited amount of data   Implementation example   var cookieParser   require  cookie-parser     app use cookieParser      app get      function req  res        var context   req cookies  context        res clearCookie  context     httpOnly  true         res render  home jade   context      Here context is just a string  you will have to provide a valid context for your template engine      app post   category   function req  res        res cookie  context    myContext     httpOnly  true         res redirect

User · Answer

The easiest way I have found to pass data between routeHandlers to use next   no need to mess with redirect or sessions  Optionally you could just call your homeCtrl req res  instead of next   and just pass the req and res  var express    require  express    var jade       require  jade    var http       require  http      var app      express    var server   http createServer app                     Routing                      Move route middleware into named    functions function homeCtrl req  res            Prepare the context     var context   req dataProcessed      res render  home jade   context      function categoryCtrl req  res  next            Process the data received in req body        instead of res redirect           req dataProcessed   somethingYouDid      return next           optionally - Same effect        accept no need to define homeCtrl        as the last piece of middleware        return homeCtrl req  res  next      app get      homeCtrl    app post   category   categoryCtrl  homeCtrl

User · Answer

app get   category   function req  res      var string   query   res redirect    valid     string        in the ejs you can directly use valid   lt   var k   valid   gt

User · Answer

You can pass small bits of key value pair data via the query string   res redirect    error denied      And javascript on the home page can access that and adjust its behavior accordingly   Note that if you don t mind  category staying as the URL in the browser address bar  you can just render directly instead of redirecting  IMHO many times people use redirects because older web frameworks made directly responding difficult  but it s easy in express   app post   category   function req  res          Process the data received in req body    res render  home jade    error   denied           As  Dropped on Caprica commented  using AJAX eliminates the URL changing concern

User · Answer

Here s what I suggest without using any other dependency   just node and express  use app locals  here s an example        app get      function req  res            var context   req app locals specialContext          req app locals specialContext   null          res render  home jade   context               or if you are using ejs         res render  home    context  context                  function middleware req  res  next            req app locals specialContext     your context goes here           res redirect

User · Answer

There are a few ways of passing data around to different routes   The most correct answer is  of course  query strings   You ll need to ensure that the values are properly encodeURIComponent and decodeURIComponent   app get   category   function req  res      var string   encodeURIComponent  something that would break      res redirect    valid     string         You can snag that in your other route by getting the parameters sent by using req query   app get      function req  res      var passedVariable   req query valid       Do something with variable       For more dynamic way you can use the url core module to generate the query string for you   const url   require  url        app get   category   function req  res        res redirect url format          pathname             query               a   1             b   2             valid   your string here                             So if you want to redirect all req query string variables you can simply do   res redirect url format          pathname             query req query                  And if you are using Node    7 x you can also use the querystring core module  const querystring   require  querystring        app get   category   function req  res          const query   querystring stringify              a   1             b   2             valid   your string here                  res redirect        query          Another way of doing it is by setting something up in the session   You can read how to set it up here  but to set and access variables is something like this   app get   category   function req  res      req session valid   true    res redirect             And later on after the redirect     app get      function req  res      var passedVariable   req session valid    req session valid   null     resets session variable      Do something       There is also the option of using an old feature of Express  req flash   Doing so in newer versions of Express will require you to use another library   Essentially it allows you to set up variables that will show up and reset the next time you go to a page   It s handy for showing errors to users  but again it s been removed by default   EDIT  Found a library that adds this functionality   Hopefully that will give you a general idea how to pass information around in an Express application

[node.js] How do I redirect in expressjs while passing some context?

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