[nodejs] PHP to node.js

On Nov 18, 2014 2:51 AM, Vasa <vijayaraj.rajasekar@gmail.= com> wrote:

>
This is not working because the chart is drawn before t= he sql data is retrieved. This is common
as people start getting going in node. Move t= he drawing parts into the callback for the SQL
query, so it waits until the= data arrives. Unlike php, request handlers don't just run to the
bottom an= d stop. Instead, the top level is run which sets things up, which load data= , which
set things up and finally respond. Http responses aren't done until= red.end(). That can be
delayed as much as you need. Next, you'll start nesting deeply, so http://callbackhell.co= m
will be a short, good read for you. Good luck! Aria

--

Job board: http://jobs.nodejs.org/On Nov 18, 2014 2:51 AM, Vasa
<vijayaraj.rajasekar@gmail.= com> wrote:

>
This is not working because the chart is drawn before t= he sql data is retrieved. This is common
as people start getting going in node. Move t= he drawing parts into the callback for the SQL
query, so it waits until the= data arrives. Unlike php, request handlers don't just run to the
bottom an= d stop. Instead, the top level is run which sets things up, which load data= , which
set things up and finally respond. Http responses aren't done until= red.end(). That can be
delayed as much as you need. Next, you'll start nesting deeply, so http://callbackhell.co= m
will be a short, good read for you. Good luck! Aria

Hello Aria,

Thank you for pointing out the bug. I am new to PHP :). I fixed it and my
PHP is working fine retrieving the data and charting.
But i am trying to move the db queries to my nodejs. So that when a request
is made, it queries the db and then tries to chart the data.
I have attached my node server. Please help me out.

Every time you have a function that you want to run first, that makes use
of callbacks, such as:

myFunc(function(err, result) { ... });

Then you need to place the code you want to run second where ... is. This
is the asynchronous nature of node. Any code where ... is will not run
until myFunc is finished internally and calls it's argument function. If
there's another synchronous function, meaning it doesn't accept a function
as a parameter, outside of myFunc it will be run first. Otherwise they will
be driven in order of the events caused by the user.

dbclient.query() needs to be inside of the anonymous (read: unnamed)
function that's passed to dbclient.connect()

Thank you for your reply.

Hi Vasa,

https://gist.github.com/oleics/36fd5049cf2f848e34a5

It's not working and I will not finish this gist, but you can use it
as a starting point, if you want to.

Two random notes:

* I see no need to require fs or socket.io. Stick to the minimum you
need, everything else is just confusing, even if require('socket.io')
might look cool ^^
* Express is a shortcut for the http-module, a very very handy shortcut.

Have fun!

Hello Oliver,

Thank you for the code. This is really helpful.

About the socketio :) i do need it in my application. I am trying to
implement a chart that is real-time.
nodejs server connects to my database using socket io.

Vasa,

I am curious why you have or need both PHP and NodeJS? Ignore this if you have already proceeded past that point and Aria might have a quick answer for your question above.

Is there a typo in the above? Did you mean NodeJS where you write PHP, above?

  —ravi

Ravi

I am developing an application that queries mysql database (that gets
updated realtime) whenever there is a http request and draws a chart with
the data. Basically i am POPULATING DATA USING SERVER SIDE CODE. I found a
sample in php which works fine for small database. But it fails for large
databases. The chart displays nothing for large data. So i am trying to
create a nodejs(asynchronous) which is the solution. I have provided the
php files and my webserver.js(nodejs). I never mentioned that my
webserver.js is final. It has method stubs that needs to be developed. I am
new to nodejs, PHP or for that matter Web applications. I am trying to
learn while developing my application. Have i made myself clear. Can you
help me out with the code

Vasa,

It seems your webserver.js is incomplete? Either that or you forgot to call
res.end() in there.
From what I see, you read file names the database? Then read those files?
What do you want to do with them? Let's say you just want to respond with a
JSON of the files you found in the directories you queried.

You'd have to make a few changes to webserver.js.

1. in your request handler, you have an `if(err){return;}` block. You
should do something like `if(err) { res.status(500); res.end(err);}`. That
would close the request (that is still waiting for you to end it after you
went to the database).

2. After that if block, you should do something with results. Like,
res.json(files);. That would send back the response as content-type
application/json and end the request.

Hope that helps.

Please ignore the older webserver.js file. This is the updated one with
method stubs that needs to be developed

Hello zladuric,

Thank you for your inputs. I know my webserver.js (which is my nodejs file)
is incomplete. I have just included method stubs that needs to be
developed.

Alright, let me explain what i am trying to do.

           I am developing an application that queries mysql database (that
gets updated realtime) whenever
           there is a http request and draws a chart with the data.
  Basically i am POPULATING DATA USING SERVER
           SIDE CODE. I found a sample in php which works fine for small
database. But it fails for large databases.
           The chart displays nothing for large data. So i am trying to
create a nodejs(asynchronous) which is the solution.

Can you make the changes in the webserver.js file and post it here. That
would be of great help to any beginner here. Thanks again