Zero-Configuration Debugging

Overview

In case of zero-configuration debugging, you do not need to create any debug configuration. Instead, you open the starting page of your PHP application in the browser manually, and then activate the debugging engine from the browser, while IntelliJ IDEA listens to incoming debugger connections.

To enable starting and stopping the debugging engine from the browser manually, you need to set a special GET/POST or COOKIE parameter. You can do it manually in the php.ini configuration file or generate the Start Debugger/Stop Debugger bookmarklets on the toolbar of your browser. These bookmarklets provide control over the debugger cookie, through them you will activate and deactivate the debugger.

For more details about setting the parameters manually, see Starting the Debugger for Xdebug and Zend Debugger GET Request Parameters for Zend Debugger.

You can also specify the scripts requests to which you want IntelliJ IDEA to ignore during debugging. This approach can be useful, when your application contains scripts that use AJAX. Suppose you have a menu-ajax-script.php that "reloads" a part of your web page. This script works properly so you do not need to debug it. However, this script is still requested during the debugging session. To have incoming connections to this script ignored, add the menu-ajax-script.php script to the skipped paths list. You can also group such scripts into folders and add these folders to the "ignore list".

Preparing the debugging engine

Before you start debugging, make sure that you have a debugging engine installed and configured properly. IntelliJ IDEA supports debugging with two most popular tools: Xdebug and Zend Debugger. These tools cannot be used simultaneously because they block each other. To avoid this problem, you need to update the corresponding sections in the php.ini file as described in Configuring Xdebug and Configuring Zend Debugger.

To open the active php.ini file in the editor:

1. Open the Settings / Preferences Dialog by pressing Ctrl+Alt+S or by choosing File | Settings for Windows and Linux or IntelliJ IDEA | Preferences for macOS, and click PHP under Languages & Frameworks.
2. On the PHP page that opens, click next to the CLI Interpreter field.
3. In the CLI Interpreters dialog box that opens, the Configuration File read-only field shows the path to the active php.ini file. Click Open in Editor.

Setting the breakpoints

Breakpoints are source code markers used to trigger actions during a debugging session. Typically, the purpose behind setting a breakpoint is to suspend program execution to allow you to examine program data. However, IntelliJ IDEA can use breakpoints as triggers for a variety of different actions. Breakpoints can be set at any time during the debugging process. Your breakpoints don't affect your source files directly, but the breakpoints and their settings are saved with your IntelliJ IDEA project so you can reuse them across debugging sessions.

1. Place the caret on the desired line of the source code.

   Breakpoints can be set in the PHP context inside *.php, *.html, and files of other types. Only executable lines are valid locations for line breakpoints. Comments, declarations, and empty lines are not valid locations for the

2. Do one of the following:
   • Click the left gutter area at a line where you want to toggle a breakpoint.
   • On the main menu, choose Run | Toggle Line Breakpoint.
   • Press Ctrl+F8.

Generating the Start Debugger/Stop Debugger bookmarklets

These bookmarklets will appear on the toolbar of your browser. They provide control over the debugger cookie, through them you will activate and deactivate the debugger.

1. Enable the Bookmarks toolbar in your browser by doing one of the following depending on the browser type:
   • In Firefox, choose View | Toolbar | Bookmarks Toolbar.
   • In Chrome, choose Bookmarks | Show bookmarks bar.
2. Open the Settings / Preferences Dialog by pressing Ctrl+Alt+S or by choosing File | Settings for Windows and Linux or IntelliJ IDEA | Preferences for macOS. Expand the Languages & Frameworks node, and then click Debug under PHP.
3. On the Debug page, that opens, click the Use debugger bookmarklets to initiate debugger from your favorite browser link.
4. On the Zend Debugger & Xdebug bookmarklets page that opens, check the debugging engine settings and click Generate. The bookmarks for listed debugging-related actions are generated.
5. Drag the generated links to the bookmark toolbar in your browser.

Initiating a debugging session and examining the suspended program

1. Generate the bookmarklets to toggle the debugger through. These bookmarklets will appear on the toolbar of your browser. They provide control over the debugger cookie, through them you will activate and deactivate the debugger.
   1. Enable the Bookmarks toolbar in your browser by doing one of the following depending on the browser type:
      • In Firefox, choose View | Toolbar | Bookmarks Toolbar.
      • In Chrome, choose Bookmarks | Show bookmarks bar.
   2. Open the Settings / Preferences Dialog by pressing Ctrl+Alt+S or by choosing File | Settings for Windows and Linux or IntelliJ IDEA | Preferences for macOS. Expand the Languages & Frameworks node, and then click Debug under PHP.
   3. On the Debug page, that opens, click the Use debugger bookmarklets to initiate debugger from your favorite browser link.
   4. On the Zend Debugger & Xdebug bookmarklets page that opens, check the debugging engine settings and click Generate. The bookmarks for listed debugging-related actions are generated.
   5. Drag the generated links to the bookmark toolbar in your browser.
2. Set the breakpoints, where necessary.
3. Toggle the Start Listen PHP Debug Connections button so it changes to . After that IntelliJ IDEA starts listening to the port of the debugging engine used in the current project. Ports for debuggers are set at the IntelliJ IDEA level in the Debug dialog box (File | Settings | PHP | Debug ).
4. Open the starting page of your application in the browser, choose the Start debugger bookmark to activate the debugging engine from the browser, re-load the current page (the starting page of the application), and then return to IntelliJ IDEA.
5. As soon as the debugger suspends on reaching the first breakpoint, examine the application by analyzing frames. A frame corresponds to an active method or function call and stores the local variables of the called method or function, the arguments to it, and the code context that enables expression evaluation. All currently active frames are displayed on the Frames pane of the Debug tool window. where you can switch between them and analyze the information stored therein in the Variables and Watches panes. For more details, see the section Examining Suspended Program.
6. Continue running the program and examine its frames as soon as it is suspended again.
   • To control the program execution manually, step through the code using the commands under the Run menu or toolbar buttons: Step Into (F7), Step Out (Shift+F8), Step Over (F8), and others. For more details, see Stepping Through the Program.
   • To have the program run automatically up to the next breakpoint, resume the session by choosing Run | Resume Program or pressing F9

Troubleshooting

During a debugging session you may encounter one of the following problems:

Specifying the scripts to skip requests to

This approach can be useful, when your application contains scripts that use AJAX. Suppose you have a menu-ajax-script.php that "reloads" a part of your web page. This script works properly so you do not need to debug it. However, this script is still requested during the debugging session. To have incoming connections to this script ignored, add the menu-ajax-script.php script to the skipped paths list. You can also group such scripts into folders and add these folders to the "ignore list".

1. Open the Settings / Preferences Dialog by pressing Ctrl+Alt+S or by choosing File | Settings for Windows and Linux or IntelliJ IDEA | Preferences for macOS. Expand the PHP node under Languages & Frameworks, and then click Skipped Paths under Debug.
2. On the Skipped Paths page that opens, configure an "ignore list" of scripts and folders with scripts not to be invoked if IntelliJ IDEA receives incoming connections to them.
   • To add a new entry to the list, click the Add button or press Alt+Insert. Then click the Browse button and in the dialog box that opens choose the file or folder to skip connections to.
   • To remove an entry from the list, select it and click the Remove button or press Alt+Delete. The script will be now executed upon receiving requests to it.
3. To have IntelliJ IDEA inform you every time it receives a request to a script to be skipped, select the Notify about skipped paths check box.

Starting a debugging session from the command line

You can start debugging a PHP CLI script from the command line, having IntelliJ IDEA listen for incoming debugger connections.

1. Set the breakpoints where necessary.
2. On the toolbar, toggle the Start Listening for PHP Debug Connections button or choose Run | Start Listening for PHP Debug Connections on the main menu.
3. Start the script with debugger options depending on the debugging engine you are using - Xdebug or Zend Debugger.