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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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