PHP Debugging with Breakpoints - case studies, examples..? - php

I'd really like to get deeper into my php scripts and use things like breakpoints, as I'm doing with JS with firebug.
I'd like to know more about what techniques people use, and some solid examples of how to debug with breakpoints a php project.
Thing's I'd like to be able to see..
Properties of objects
Class hierarchies.. where objects are coming from, file names etc.. (useful in ZF/Magento)
Variables, types, content..
headers, post data, get data, session data, cookies..
Network / filesystem status..
I know a lot of this can be done with logging and print_r/vardump etc, but its a bit raw.. and I'd like to be able to use a "continue"/"step-over" etc command on code after hitting a breakpoint, like with firebug.
from php.ini:
zend_extension_ts = c:\wamp\bin\php\php5.2.11\ext\php_xdebug-2.1.0-5.2-vc6.dll;
xdebug.remote_enable=On;
xdebug.remote_host="localhost";
xdebug.remote_port=9000;
xdebug.remote_handler="dbgp";

xdebug + remote debugging + one of the supported clients

Use XDebug, it does most of what you require (not network/filesystem), and with it you can debug from eclipse, zend studio, pdt, or even notepad++
I keep debugging again and again when dealing with Magento, and it is super useful in this case, since Magento's function call stack is very deep.

PHP is interpreted and server side scripting language. So, there are only few editors that supports the break point in PHP. And if you are doing the server side scripting then there is no way to debug your script using break points.
However if you are planning to have basic scripting & debugging then you can go with http://www.firephp.org/. Also if you use Zend Studio editor then you will have many options on hand for debugging your script. Zend Studio supports the break point, run & debug options.
I prefer to log the execution of my script in file.
Thanks

Related

html/php debugging

I am starting a website, thus I'm learning how to program in html/css/php. For other languages I have learnt so far, there has always been an IDE or interactive console that I can type in codes directly to see how they works, access variable types etc., which makes learning and debugging a breeze. (E.g. bash, python, matlab, perl, tcl...)
Can I do the same for html and php? In the spirit stackoverflow's questions style, lemme try to make the questions a little more specific.
I know I can use php interactively on a terminal.
But that is insufficient if I want to see how it works in a html script.
Is there a browser/IDE with a console where I can input commands interactively and see the results?
For PHP:
I'd suggest to use Xdebug.
Read through this article: Debugging techniques for PHP programmers.
Note about debugging production.
For your markup:
Read Firebug-like debugger for Google Chrome.
Also, you might try Web Developer extension.
I find enabling errors is handy for general debugging. With it enabled you can see where the script failed and hone in on the error quite easily. For more advanced stuff Xdebug has it's place.
Combined with a local WAMP installation you have a great start point. Save the php script, execute it and combined with "Firebug" (FF extension) and you have a decent "beginners" tool set for debugging.
you can make your browser your ide. i do, check it out:
handy article showing how to output php to browser console. http://sarfraznawaz.wordpress.com/2012/01/05/outputting-php-to-browser-console/
as for html, download web developer extension for your browser, and validate your markup to test/debug.
You might be interested in something like Cloud9 IDE.
Check them out at: www.cloud9ide.com

How to do Debugging of PHP?

how we do basic debugging in PHP ?
Can anybody share true horror story on debugging PHP application (or (even better) on PHP framework such Codeigniter and Wordpress) ?
i love to hear real experience in case i have to encounter similar situation on my journey to learn PHP.
XDebug may be used to debug a PHP application. Basically you install this on your server and configure it in PHP.ini. Then on your desktop machine, you can setup Netbeans (and maybe Eclipse, but I have not tried that) to remote debug. When you are in a remote debug session you can do any of the things you typically expect: set breakpoints, step through code, etc.
One major annoyance when using CodeIgniter with mod_rewrite is that the debugger gets confused by index.php not showing up in the URL. I am not sure if this is a problem on the client side or server, and whether CI "eating" the GET portion of a URL has anything to do with it. In any case, I have worked through it by copying a 'debug.php' file to the server and starting debugging with that file - everything seems to work fine after that.
I any case, I highly recommend you get setup with XDebug at some point. You may not use it everyday, but when you need it you'll be thankful you did your homework ahead of time.
Easiest option (without installing any IDE) is to use firefox FirePHP addon.
Download and install FirePHP firefox addon
Download FirePHP core library from their website
Extract FirePHP library you downloaded in step 2 and only copy FirePHP.class.php to CodeIgniter /application/libraries/ folder, but give it a name FirePHP.php without the class part
Turn PHP’s output buffering on
Start your Firefox, click the FireBug icon on the bottom lower area, or go to menu and select tools. After you turn on (set them to enable) FireBug and FirePHP, be sure to click on the Net tab next in line to HTML, CSS, Script, DOM and set it also to enable.
See this link for how to use firephp library: http://speedtech.it/2009/05/debugging-a-codeigniter-application-with-firephp/
There is one problem in using IDE debugers - it's bad for debuging AJAX applications. In this case you will need to use some of browser extension. For FireFox it's FirePHP, and gor Google Chrome it's Php console.
I checked out a lot of debuggers 2 years ago when I wanted to set up a debugging environment for myself in PHP. I posted a brief post on this, you can go through it http://forums.codewalkers.com/general-chat-93/which-php-ide-to-use-840352.html
Bottomline was that Nusphere's phped was the best and its debugbreak() function makes debugging a real bliss. With codeigniter also this works fine, no tweaks required if you have already enabled get variable. The only hiccup with codeigniter+phed is that, you cannot do code navigation like "right click and find declaration" for other files models.
Off late I have been checking out codelobster they have a codeigniter plugin, but I am not through with it yet.

REMOTELY Debugging PHP Using Eclipse

I'm a self-taught noobie, trying to debug PHP on my GoDaddy hosted server. Is this idea even rational, or do I need to continue to do all development locally and just continuously re-ftp upload the changes?
Is there some way that I can use eclipse to step through, and debug my php scripts that are hosted on a third party site?
Although I have only used Netbeans and XDebug for remote debugging, it should be possible to use Eclipse PDT and XDebug. See:
setting-eclipse-pdt-and-xdebug
Debugging PHP applications with xdebug
One caveat, however. To configure xdebug you will need to modify some settings in php.ini - I am not sure if this will be possible on a hosted server. If not, you would need to have a local server that you use for debugging, and would need to figure out another solution for your "production" environment. Which may not be a bad idea, actually, as it would give you a good place to test your changes without risking breaking anything on your actual site.
Also, I recommend that you look into Netbeans, if for no other reason than to experiment and see what it can do compared to Eclipse. One nice feature is that you can set it up to automatically ftp (or scp) changed files to the remote site. So you can make some code changes, click the debug button, and after waiting a moment for your files to upload you can be stepping through code on the remote site.
While there is definitely a case for remote debugging you should always be working locally and then uploading. Anything except the most minor of changes should be done locally tested then pushed to a server - sometimes production directly, sometimes a testing server...
Yes Eclipse supports remote debugging with Xdebug as well as the one from Zend Debugger check out Justin's links as well as This one for Zend Debugger. I think Zend has an all in one with pdt+deps and Zend Debugger - ofcourse you still need to set up the extension on the server (note link is for setup on windows but hte process should be similar).
Obligatory "Ewww GoDaddy" :-)
If the web server have XDebug installed, then you can do debugging with it. Searching for it in google yield a quite num of articles on how to do it.
Personally, I'm using CodeIgniter. I do debugging using FirePHP and PQP. Make a habit to write a good indented code. You might find your code have less bug, both syntax and logic, and easier to maintained in the future. Use a consistent white space, either tab or space. Use a consistent bracket style. It will save you from the headache when re-read it for bug or adding more feature later.
I have never needed to do a step by step debug in PHP, but when I do need to debug I just output strings of the variables at that point.
However, one thing that I found, but again never used, was FirePHP:
http://www.firephp.org/
As far as I'm aware, this is not possible in Eclipse, it is, however, possible in NetBeans, but as Nathan stated, I've never really needed to remote debug any of my PHP scripts.

FireBug extension to examine PHP variables

We have FireSymfony that allows one to view the Symfony, PHP variables in a firebug panel, so I wonder whether there is a similar extension that allows me to view PHP variables for general PHP apps ( not just Symfony apps)?
You may want to check out FirePHP. It is an extension to FireBug that allows sort of an extended logging of PHP through the Firefox Browser/Firebug Console.
Probably somewhat close to what you are looking for, even though you'd still have to make specific use of it in the PHP scripts.
I think that is part of what Symfony supports, exporting PHP variables to client side for debugging.
you see, PHP variables are located on the server, not at the client. Thus when you load the page, you won't be able to see the PHP variables from client side.
Thus if you want to debug PHP variables, you must have a way for your application to export the variables out to the client side for firebug or any other extension to debug.
In other words, it's not really possible for that to happen for ALL php applications.
Another option is Formaldehyde which integrates nicely with Firebug.

Debugging PHP

I've been using xdebug to debug and understand code in php projects for a while now, and have sometimes come into situations where it's been unclear what's going on inside of PHP.
Is it possible to set xdebug or gdb up so that i can trace into actual php builtin functions?
If you are using a macosx, solaris or recent freebsd system you can throw a little dtrace at it. It can come in handy for those all too numerous "WTF is PHP doing?" moments.
I doubt it, xdebug is intended for tracing your PHP code, not the internals. The internals are assumed to be bug-free (which obviously they aren't sometimes, but that's beyond the scope of xdebug).
You can always look at the PHP source if you want to know what the built-in functions do, but that's sometimes pretty hairy. The PHP manual docs have always served me well enough when I want to know what they'll do.
You can use gdb to trace in to the C-level code, provided you have php compiled with debug symbols. Have a look here for a start:
http://derickrethans.nl/phps_segmentation_faults_gdbfu.php
One way to test the output of the Zend engine, to peek inside at the opcodes, you can use Derick Rethan's VLD (Vulcan Logic Dissasembler), which also appears to be on PECL. Note: only works on *nix systems (see site for requirements).
Some examples of debugging these opcodes can be found on Sara Golemon's blog, in articles such as Understanding Opcodes and How long is a piece of string?.
There is also great Google Chrome extension PHP Console with php library that allows to:
See errors & exception in Chrome JavaScript console & in notification popups.
Dump any type variable.
Execute PHP code remotely.
Protect access by password.
Group console logs by request.
Jump to error file:line in your text editor.
Copy error/debug data to clipboard (for testers).
Recommend to everyone!

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