The Golden Rules

First things to set in your mind...

1. The <search> tag can only be a single line, though doesn't have to be a whole line, as partial matches work too. You should learn how to use the offset attribute to properly encompass all needed lines, but that doesn't mean you should encompass many lines. Instead of trying to include many lines from top down, try starting at the bottom and finding lines going up.
2. Less is more! Whenever possible, try to match the smallest, yet still unique part of the code. That will improve the chances of being more future-resistant and avoid breaking other mods that may have changes close to yours.
3. Pay attention to all the attribute options for each tag. There is a lot of power that is overlooked by people skimming over the syntax

How to make vQmod Scripts

UKSB from the OpenCart forums has created a great vQmod script generator here. This greatly simplifies an already simple creation process.

• http://www.opencart-extensions.co.uk/vqgen/

vQmod currently uses an xml formatted parser by default but other parsers can be created in the future as well.

A simple replace script example looks like this:

<?xml version="1.0" encoding="UTF-8"?>
<modification>
	<id>Replace 123 with ABC</id>
	<version>1.0.0</version>
	<vqmver>1.0.9</vqmver>
	<author>qphoria</author>
	
	<file name="relative/path/myfile.php">
		<operation>
		
			<search position="replace"><![CDATA[
			$var = '123';
			]]></search>
			
			<add><![CDATA[
			$var = 'ABC';
			]]></add>
			
		</operation>
	</file>	
</modification>

This script simply changes the value of a variable of "myfile.php" from "123" to "ABC" before it gets included.

Syntax

vQmod supports a number of parameters:

modification

• This is the highest level of the file and there can only be one

modification / id

• This is the name and description of the mod.
• Format: Free form text. (Informational)

modification / version

• This is the version of the mod.
• Format: Number and Decimal (1.0.0) (Informational)

modification / vqmver

• This is the minimum required version of VirtualQMod needed for the script to work.
• Format: Number and Decimal (1.0.0) (Informational)

modification / author

• This is the author of the mod.
• Format: Free form text (Informational)

modification / file

• This is the name of the file to modify.
• Requires attribute "name" as relative filename to the location of the main index.php file (e.g. catalog/controller/product/product.php). Name attribute supports a wildcard (*) character for dynamic path building. Each wildcard is limited to a single directory level.

     - catalog/view/theme/*/template/product/product.tpl
     - catalog/view/theme/*/*/product/product.tpl
     - etc

• There can be multiple file tags in a single xml file. Each file can have its own set of operations
• Optional attribute "error" set to log|skip|abort
• skip means it will simply ignore this file.
• log is the same as skip, but logs the error. (default)
• abort means to log the error and cancel the remaining operations in that particular xml script. It does not revert changes to other files already made in that script and doesn't stop other xml files.
• Wildcard paths will ignore the "error" attribute completely

modification / file / operation

• This is the wrapper of the actual operation occurring.
• There can be multiple operations to the same file tag.
• Optional attribute "error" set to skip|log|abort
• skip means all other operations will be applied even if one cannot. There will be no error in the log.
• log is the same as skip, but logs the error.
• abort means to log the error and revert to the original source. (default)

modification / file / operation / search

• This is the first required step of the operation.
• Can only search single lines, both fully and partially. But offset and index attributes will assist.
• Automatically trims whitespace and linebreaks
• One per operation tag
• Recommended to use CDATA tags to wrap code.
• Required attribute "position" set to before|after|replace|top|bottom|all.
• replace will replace the data in the search tag with the data in the add tag. (default)
• before will insert the add data before the search data
• after will insert the add data after the search data
• top will insert the add data at the top of the file. The search data is ignored.
• bottom will insert the add data at the bottom of the file. The search data is ignored.
• all will completely replace all the code in the file with the add data. The search data is ignored.
• Optional attribute "offset" to work with the position
• if the search position is before and offset 3 it will put the add data before the line, 3 lines above the searched line
• if the search position is after and offset 3 it will put the add data after the line, 3 lines below the searched line
• if the search position is replace and offset 3 it will remove the code from the search line and the next 3 lines and replace it with the add data
• if the search position is top and offset 3 it will put the code before the line, 3 lines below the top of the file
• if the search position is bottom and offset 3 it will put the code after the line, 3 lines above the bottom of the file
• Optional attribute "index" for specifying which instances of a search tag should be acted on
• If the search string is "echo" and there are 5 echos in the file, but only want to replace the 1st and 3rd, use index="1,3"
• Comma delimited for multiple instances starting with "1"
• Leave out or set to FALSE to replace all instances. (default)
• Optional attribute "regex" for specifying whether or not to search a regex pattern.
• If true, the search data should be a valid regex pattern
• Leave out or set to FALSE to use normal string search (default)
• Optional attribute "trim" set to true|false
• true will trim away whitespace and linebreaks.
• leave out or set to true to trim. (default is true)

modification / file / operation / add

• This is the second required step of the operation.
• Can be multiple lines
• One per operation.
• Location of added data depends on the position attribute of the search command.
• Use CDATA tags to wrap code.
• Optional attribute "trim" set to true|false
• true will trim away whitespace and linebreaks.
• leave out or set to false to not trim. (default is false)

<![CDATA[ ]]>

• These are called CDATA tags and they are used by xml to specify that the data between should not be evaluated. It's recommended you always use these for data between the search and add operation tags