Create Folder Structure And Configuration Files¶
Before we write the first line of code, we must arrange the
infrastructure of the extension. Beside the folder structure there are some
minimum needed configuration files counting. We put the unique identifier of
our extension (extension-key) as
store_inventory, and thus
we specify at the same time the name of the extension as
The name of an extension is always written in UpperCamelCase (beginning with a capital letter, then upper and lower letters; no underscore), while the extension key may only contain small letters and underscore (lower_underscore). You will find an overview of the name conventions in appendix A, Coding Guidelines.
Extensions can be stored at different places in TYPO3. Locally
installed extensions are the rule. These are in the folder
typo3conf/ext/. System extensions are delivered with the
TYPO3-distribution and are in the folder
Extbase or Fluid are examples of system extensions. The two paths are
below the installation folder of TYPO3, in which also lies the file
Then, in the folder for local extensions
typo3conf/ext/ we create the folder
store_inventory. The name of this folder
must be written like the extension key and therefore in lower-case letters,
and where appropriate, with underscores. On the uppermost level lie the
Classes contains all PHP classes, with the exception of external PHP libraries. The folder
Resources contains two directories named
Resources/Private/ contains subfolders like
Language. These files can only be accessed through the file system.
Resources/Public/ contains subfolders like
Js. These files can be accessed through the web browser.
Within the folder
Classes are the folders
Domain. In our example, the folder
Controller contains only one class that will control
the entire process of listing creation later. The folder Domain again contains the two folders
Repository. Resulting from all this, the folder structure within the extension folder
store_inventory should look as in image 4-1.
A single configuration file named
ext_emconf.php is required by TYPO3
to allow for loading the extension. The file is located in the extension’s
top level folder (
store_inventory/). You can copy and adapt this file
from an existing extension. Later on it is advisable to have it generated by
the extension_builder extension.
ext_emconf.php contains the meta information for the
extension like title, description, status, name of the author and more. It
is not special in any way and does not differ from the one of any other
extension. Find a complete reference in chapter
Declaration file of the Core Api Reference manual.
<?php $EM_CONF[$_EXTKEY] = [ 'title' => 'Store Inventory', 'description' => 'An extension to manage a stock.', 'category' => 'plugin', 'author' => 'John Doe', 'author_company' => 'John Doe Inc.', 'author_email' => 'firstname.lastname@example.org', 'state' => 'alpha', 'clearCacheOnLoad' => true, 'version' => '0.0.0', 'constraints' => [ 'depends' => [ 'typo3' => '8.7.0-8.9.99', ], ], 'autoload' => [ 'psr-4' => [ 'MyVendor\\StoreInventory\\' => 'Classes' ], ], ];
In previous versions of TYPO3 the extension icon was named
ext_icon.gif. Starting with TYPO3 8 you can choose between PNG or SVG
format. The file must have the name
Extension.svg and must be stored in the
The icon will be displayed in the extension manager and in the TYPO3 extension
If the extension has namespaced classes following the PSR-4 standard, then you
can add the autoload array to your
After the basic structure was constructed, the extension can already be shown in the extension manager and can be installed. But first we turn to our domain.