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Transformations

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Note

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You need to have configured the phpMyAdmin configuration storage for using transformations -feature.

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Introduction

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To enable transformations, you have to setup the column_info -table and the proper directives. Please see the Configuration on how to do so.

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You can apply different transformations to the contents of each -column. The transformation will take the content of each column and -transform it with certain rules defined in the selected -transformation.

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Say you have a column ‘filename’ which contains a filename. Normally -you would see in phpMyAdmin only this filename. Using transformations -you can transform that filename into a HTML link, so you can click -inside of the phpMyAdmin structure on the column’s link and will see -the file displayed in a new browser window. Using transformation -options you can also specify strings to append/prepend to a string or -the format you want the output stored in.

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For a general overview of all available transformations and their -options, you can consult your <www.your-host.com>/<your-install- -dir>/transformation_overview.php installation.

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For a tutorial on how to effectively use transformations, see our -Link section on the -official phpMyAdmin homepage.

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Usage

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Go to your tbl_structure.php page (i.e. reached through clicking on -the ‘Structure’ link for a table). There click on “Change” (or change -icon) and there you will see three new fields at the end of the line. -They are called ‘MIME-type’, ‘Browser transformation’ and -‘Transformation options’.

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  • The field ‘MIME-type’ is a drop-down field. Select the MIME-type that -corresponds to the column’s contents. Please note that transformations -are inactive as long as no MIME-type is selected.
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  • The field ‘Browser transformation’ is a drop-down field. You can -choose from a hopefully growing amount of pre-defined transformations. -See below for information on how to build your own transformation. -There are global transformations and mimetype-bound transformations. -Global transformations can be used for any mimetype. They will take -the mimetype, if necessary, into regard. Mimetype-bound -transformations usually only operate on a certain mimetype. There are -transformations which operate on the main mimetype (like ‘image’), -which will most likely take the subtype into regard, and those who -only operate on a specific subtype (like ‘image/jpeg’). You can use -transformations on mimetypes for which the function was not defined -for. There is no security check for you selected the right -transformation, so take care of what the output will be like.
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  • The field ‘Transformation options’ is a free-type textfield. You have -to enter transform-function specific options here. Usually the -transforms can operate with default options, but it is generally a -good idea to look up the overview to see which options are necessary. -Much like the ENUM/SET-Fields, you have to split up several options -using the format ‘a’,’b’,’c’,...(NOTE THE MISSING BLANKS). This is -because internally the options will be parsed as an array, leaving the -first value the first element in the array, and so forth. If you want -to specify a MIME character set you can define it in the -transformation_options. You have to put that outside of the pre- -defined options of the specific mime-transform, as the last value of -the set. Use the format “’; charset=XXX’”. If you use a transform, for -which you can specify 2 options and you want to append a character -set, enter “‘first parameter’,’second parameter’,’charset=us-ascii’”. -You can, however use the defaults for the parameters: “’‘,’‘,’charset -=us-ascii’”. The default options can be configured using -$cfg['DefaultTransformations']
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File structure

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All specific transformations for mimetypes are defined through class -files in the directory ‘libraries/classes/Plugins/Transformations/’. Each of -them extends a certain transformation abstract class declared in -libraries/classes/Plugins/Transformations/Abs.

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They are stored in files to ease up customization and easy adding of -new transformations.

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Because the user cannot enter own mimetypes, it is kept sure that -transformations always work. It makes no sense to apply a -transformation to a mimetype the transform-function doesn’t know to -handle.

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There is a file called ‘transformations.lib.php‘ that provides some -basic functions which can be included by any other transform function.

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The file name convention is [Mimetype]_[Subtype]_[Transformation -Name].class.php, while the abtract class that it extends has the -name [Transformation Name]TransformationsPlugin. All of the -methods that have to be implemented by a transformations plug-in are:

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  1. getMIMEType() and getMIMESubtype() in the main class;
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  2. getName(), getInfo() and applyTransformation() in the abstract class -it extends.
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The getMIMEType(), getMIMESubtype() and getName() methods return the -name of the MIME type, MIME Subtype and transformation accordingly. -getInfo() returns the transformation’s description and possible -options it may receive and applyTransformation() is the method that -does the actual work of the transformation plug-in.

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Please see the libraries/classes/Plugins/Transformations/TEMPLATE and -libraries/classes/Plugins/Transformations/TEMPLATE_ABSTRACT files for adding -your own transformation plug-in. You can also generate a new -transformation plug-in (with or without the abstract transformation -class), by using -scripts/transformations_generator_plugin.sh or -scripts/transformations_generator_main_class.sh.

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The applyTransformation() method always gets passed three variables:

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  1. $buffer - Contains the text inside of the column. This is the -text, you want to transform.
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  2. $options - Contains any user-passed options to a transform -function as an array.
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  3. $meta - Contains an object with information about your column. The -data is drawn from the output of the mysql_fetch_field() function. This means, all -object properties described on the manual page are available in this -variable and can be used to transform a column accordingly to -unsigned/zerofill/not_null/... properties. The $meta->mimetype -variable contains the original MIME-type of the column (i.e. -‘text/plain’, ‘image/jpeg’ etc.)
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