Revision as of 08:30, 26 May 2010

The main advantages of plugins are:

• Upgrades are much easier.
• The plugin code is stored in a single place.
• Plugins can be easily disabled when they are not needed anymore.

Common use cases:

• Adding a new server-side command (i.e. fileditor and imageresize plugin).
• Working with uploaded files (i.e. watermark plugin).
• Extending information returned by the Init command (i.e. imageresize plugin).

Creating a plugin

Step1: Create plugin folder

Create a directory for your plugin inside of the "plugins" directory (by default CKFinder comes with three plugins: dummy, fileeditor, imagreresize). Let's use "myplugin" as the plugin name and use the same name for our new folder.

Step2: Create plugin file

Inside of your plugin's folder ("myplugin") create an empty file named plugin.asp.

Step3: Add plugin definition

// Let's create an empty ASP file for now

Step4: Enable plugin

Add an INCLUDE statement in the ASP configuration file (config.asp):

<!-- #INCLUDE file="plugins/myplugin/plugin.asp" -->

ASP plugin system

Hooks

CKFinder provides several hooks that can be used to extend the functionality of the CKFinder application. Assigning a function (also known as an event handler) to a hook will cause that function to be called at the appropriate point in the main CKFinder code, to perform whatever additional task(s) the developer thinks would be useful at that point. Each hook can have multiple handlers assigned to it, in which case it will call the functions in the order that they are assigned.

Hooks should be assigned in a plugin file. To assign a event listener to a hook call:

CKFinder_AddHook "EventName", CommandHandler

where EventName is the name of a hook and CommandHandler is an object that contains a method named OnEventName.

Available hooks

Enabling JavaScript plugin

Sometimes a server side plugin might come with a client side (JavaScript) plugin, that should be automatically enabled when the server side plugin is enabled.
The $config['Plugins'] variable is a special array that does that.

To enable a plugin, simply add it's name to this array.

$config['Plugins'][] = 'myplugin';

This code is virtually equal to specyfying in config.js:

config.extraPlugins = 'myplugin';

but the advantage of defining it in plugin.php is that it will be enabled only when the server side plugin is also enabled.

Sample plugin: FileSize (adding new server side command - complete example)

Introduction

Probably the best way to learn new things is to write a code, so let's write a plugin that adds a new server side command to the connector. We'll create a command that returns a size of a given file.

The FileSize plugin should provide a new command named "FileSize", in other words, calling:

/ckfinder/core/connector/asp/connector.asp?command=FileSize&type=Files&currentFolder=%2F&fileName=foobar.jpg

(assuming that foobar.jpg exists) should return a valid XML response:

<Connector resourceType="Files">
<Error number="0"/>
<CurrentFolder path="/" url="/ckfinder/userfiles/files/" acl="255"/>
<FileSize size="5647"/>
</Connector>

For the sake of simplicity, we'll first create a simple plugin.asp that just does exactly what we need:

<script runat="server" language="VBScript">

class CKFinder_Connector_CommandHandler_FileSize
	'pseudo inheritance
	private base

	' Since we want to send a XML response, we'll extend the XmlCommandHandlerBase class
	Private Sub Class_Initialize()
		Set base = new CKFinder_Connector_CommandHandler_XmlCommandHandlerBase
		Set base.child = me
	End Sub

	' Pseudo inheritance
	Public Property Get currentFolder()
		Set currentFolder = base.currentFolder
	End Property

	Public Sub sendResponse(response)
		base.sendResponse(response)
	End sub

	Public Property Get ErrorHandler()
		Set ErrorHandler = base.ErrorHandler
	End Property

    ' (5) The buildXml method is used to construct an XML response
    function buildXml( oXML )
		Dim fileName
		fileName = request("fileName")

		Dim oUFS
		Set oUFS = oCKFinder_Factory.UtilsFileSystem

		Dim filePath
		filePath = oUFS.combinePaths(currentFolder.getServerPath(), fileName)

		' (6) Adding a <FileSize> element to the XML response.
		Dim size, oNode
		size = oUFS.GetFileSize(filePath)
        Set oNode = oXML.connectorNode.addChild("FileSize")
        oNode.addAttribute "size", size

    End function

    ' Our event listener:
    ' (3) Register the "FileSize" command
    public function onBeforeExecuteCommand( command )
        if ( command = "FileSize" ) then
            ' The sendResponse method is defined in XmlCommandHandlerBase, it creates 
            ' a basic XML response and calls the buildXml()method 
            sendResponse( response )
            ' false = stop further execution.
            onBeforeExecuteCommand = False
            Exit function
        End if

        onBeforeExecuteCommand = True
    End Function

End Class

Dim CommandHandler_FileSize
Set CommandHandler_FileSize = new CKFinder_Connector_CommandHandler_FileSize

' Object assigned to a hook must contain event listener named "onEventName"
' (the event name is BeforeExecuteCommand, so we must define an onBeforeExecuteCommand method).
CKFinder_AddHook "BeforeExecuteCommand", CommandHandler_FileSize
CKFinder_AddPlugin "myplugin"

</script>

Step1: Register an event handler

$config['Hooks']['BeforeExecuteCommand'][] = array($CommandHandler_FileSize, "onBeforeExecuteCommand");

Step2: Create a class

If your plugin returns an XML response, you'll usually just extend the XmlCommandHandlerBase class to reduce the amount of code to write, however it is not a requirement.

// (2) Include base XML command handler
require_once CKFINDER_CONNECTOR_LIB_DIR . "/CommandHandler/XmlCommandHandlerBase.php";

// Since we will send a XML response, we'll extend the XmlCommandHandlerBase
class CKFinder_Connector_CommandHandler_FileSize extends CKFinder_Connector_CommandHandler_XmlCommandHandlerBase

Step3: Create an event handler

Our event handler defined in (1) is called "onBeforeExecuteCommand", so let's define such function.

function onBeforeExecuteCommand( &$command )
// ...

Step4: Create the buildXml method

In the onBeforeExecuteCommand method we have called sendResponse. The sendResponse method is defined in XmlCommandHandlerBase class, it creates a basic XML response and calls the buildXml method, which we need to define.

function buildXml()
// ...

Step5: Construct the XML response

The main task of the buildXml method is to construct an XML response, so we're doing it below:

$oNode = new Ckfinder_Connector_Utils_XmlNode("FileSize");
$oNode->addAttribute("size", $size);
$this->_connectorNode->addChild($oNode);

Full source code

plugin.asp

The full source code of a plugin with all necessary security checks: (save the code as plugin.php in "plugins/myplugin" folder)

<script runat="server" language="VBScript">

class CKFinder_Connector_CommandHandler_FileSize
	'pseudo inheritance
	private base

	' Since we want to send a XML response, we'll extend the XmlCommandHandlerBase class
	Private Sub Class_Initialize()
		Set base = new CKFinder_Connector_CommandHandler_XmlCommandHandlerBase
		Set base.child = me
	End Sub

	Private Sub Class_Terminate()
		Set base.child = Nothing
		Set base = Nothing
	End Sub

	' Pseudo inheritance
	Public Property Get currentFolder()
		Set currentFolder = base.currentFolder
	End Property

	Public Sub sendResponse(response)
		base.sendResponse(response)
	End sub

	Public Property Get ErrorHandler()
		Set ErrorHandler = base.ErrorHandler
	End Property

    ' (5) The buildXml method is used to construct an XML response
    function buildXml( oXML )

        if not(currentFolder.checkAcl(CKFINDER_CONNECTOR_ACL_FILE_VIEW)) then
			errorHandler.throwError CKFINDER_CONNECTOR_ERROR_UNAUTHORIZED, "", "ACL check failed"
		End if

		Dim resourceTypeInfo
		Set resourceTypeInfo = currentFolder.getResourceTypeConfig()

		Dim fileName
		fileName = request("fileName")
		If (fileName="") then
			errorHandler.throwError CKFINDER_CONNECTOR_ERROR_INVALID_NAME, "", "Missing filename"
		End if

		Dim oUFS
		Set oUFS = oCKFinder_Factory.UtilsFileSystem

        if (Not oUFS.checkFileName(fileName) or resourceTypeInfo.checkIsHiddenFile(fileName)) then
			errorHandler.throwError CKFINDER_CONNECTOR_ERROR_INVALID_REQUEST, "", "Invalid filename"
		End if

        if (Not resourceTypeInfo.checkExtension(fileName)) then
 			errorHandler.throwError CKFINDER_CONNECTOR_ERROR_INVALID_REQUEST, "", "Invalid extension"
		End if

		Dim filePath
		filePath = oUFS.combinePaths(currentFolder.getServerPath(), fileName)

		If Not(oUFS.fileExists(filePath)) then
 			errorHandler.throwError CKFINDER_CONNECTOR_ERROR_FILE_NOT_FOUND, "", "File doesn't exists: " & filePath
		End if

		' (6) Adding a <FileSize> element to the XML response.
		Dim size, oNode
		size = oUFS.GetFileSize(filePath)
        Set oNode = oXML.connectorNode.addChild("FileSize")
        oNode.addAttribute "size", size

    End function

    ' Our event listener:
    ' (3) Register the "FileSize" command
    public function onBeforeExecuteCommand( command )
        if ( command = "FileSize" ) then
            ' The sendResponse method is defined in XmlCommandHandlerBase, it creates 
            ' a basic XML response and calls the buildXml()method 
            sendResponse( response )
            ' false = stop further execution.
            onBeforeExecuteCommand = False
            Exit function
        End if

        onBeforeExecuteCommand = True
    End Function

End Class

	Dim CommandHandler_FileSize
If (TypeName(oCKFinder_Factory) <> "Empty") then
	Set CommandHandler_FileSize = new CKFinder_Connector_CommandHandler_FileSize

	' Object assigned to a hook must contain event listener named "onEventName"
	' (the event name is BeforeExecuteCommand, so we must define an onBeforeExecuteCommand method).
	CKFinder_AddHook "BeforeExecuteCommand", CommandHandler_FileSize
	CKFinder_AddPlugin "myplugin"
End if

</script>

plugin.js

.. and the client side (JavaScript) plugin that will call the FileSize command: (save the code as plugin.js in "plugins/myplugin" folder)

CKFinder.addPlugin( 'myplugin', function( api ) {
	api.addFileContextMenuOption( { label : 'File Size', command : "FileSize" } , function( api, file )
	{
		api.connector.sendCommand( 'FileSize', { fileName : api.getSelectedFile().name }, function( xml )
		{
			if ( xml.checkError() )
				return;

			var size = xml.selectSingleNode( 'Connector/FileSize/@size' );
			api.openMsgDialog( "", "The exact size of a file is: " + size.value + " bytes");
		} );
	});
});