How to use NodeJS + ExpressJS to pass an array to Jade for display?

express, javascript, mysql, node.js, pug

Solution

The problem is that you're trying to render a query outside the HTTP flow. That could be your intention (in which case I'm interested in hearing what exactly you're trying to do with the rendered result), but usually, you wait for an HTTP request before you return the results of your query.

For example:

app.get('/test', function(req, res) {
  // connect to MySQL server
  var client = mysql.createConnection(sqlInfo);
  client.connect();

  // Perform query and wait for results
  client.query( "SELECT * FROM list ORDER BY status ASC LIMIT 25", function(err, row, fields) {
    // Done with the connection
    client.end();

    // Handle error
    if (err) throw err;
    else {
      // We got a result: render it
      var applications = row;
      res.render("applications", { applications : applications });
    }
  });
});

A few pointers:

- You can look at the results by opening `http://localhost:PORT/test`

- Take a look at connection pooling for MySQL, which maintains a pool of connections to the MySQL server instead of having to create a new connection each time you handle a request;

- In your example code, you were sending `client.end()` right after `client.query()`, but without waiting for the query to return any results. So I moved `client.end()` to inside the code which handles the query result, to make sure the connection is ended only after the results are returned;

- in your template, you reference a variable called `data`, but I think that should be `applications`;

Problem

I come from a very "functional" style of programming (PHP, Lua, C) and I'm trying to transition my thinking to the MVC model NodeJS uses. Currently, this is a very steep learning curve for me. I've been banging my head against the wall trying to get a simple MySQL array to print out to Jade. app.js ``` /** * Module dependencies. */ var express = require('express') , routes = require('./routes') , user = require('./routes/user') , http = require('http') , path = require('path') , mysql = require('mysql'); var app = express(); // all environments app.set('port', process.env.PORT || 3000); app.set('views', __dirname + '/views'); app.set('view engine', 'jade'); app.use(express.favicon()); app.use(express.logger('dev')); app.use(express.bodyParser()); app.use(express.methodOverride()); app.use(app.router); app.use(express.static(path.join(__dirname, 'public'))); // development only if ('development' == app.get('env')) { app.use(express.errorHandler()); } app.get('/', routes.index); app.get('/users', user.list); //MySQL var sqlInfo = { host: '12.34.56.78', user: 'user', password: 'pass', database: 'user' } var client = mysql.createConnection(sqlInfo); client.connect(); client.query( "SELECT * FROM list ORDER BY status ASC LIMIT 25", function(err, row, fields){ if (err) throw err; else { var applications = row; app.render("applications", applications, function(err, html){}); } }); client.end(); http.createServer(app).listen(app.get('port'), function(){ console.log('Express server listening on port ' + app.get('port')); }); ``` index.jade ``` extends layout block content div.container div.content - if (typeof(applications) !== 'undefined') ul - each app in data li= app.status - else p Blank slate mate... div.footer ``` I think my issue is stemming from the app.render/res.render function... The concept of this function is not really clicking and I'm having problems getting it to work like I've seen in so many other MySQL + NodeJS examples. Any tips or hints are much appreciated!

Original source