Constants

Changed in version 12.0

The TypoScript management tools are now found in backend module Site Management > TypoScript. It was formerly found in "Page > Template".

Screenshot of the TYPO3 Backend showing the constant editor

The Constant Editor in the TYPO3 backend

Constants are values defined in the Constants field of a template. They follow the syntax of ordinary TypoScript and are case sensitive! They are used to manage in a single place values, which are later used in several places.

Defining constants

Other than constants in programming languages, values of constants in TypoScript can be overwritten. Constants in TypoScript can more be seen as variables in programming languages.

Reserved name

The object or property "file" is always interpreted as data type resource. That means it refers to a file, which has to be uploaded in the TYPO3 CMS installation.

Multi-line values: The ( ) signs

Constants do not support multiline values!

You can use environment variables to provide instance specific values to your constants. Refer to getEnv for further information.

Example

Here bgCol is set to "red", file.toplogo is set to fileadmin/logo.gif and topimg.file.pic2 is set to fileadmin/logo2.gif, assuming these files are indeed available at the expected location.

bgCol = red
file {
  toplogo = fileadmin/logo.gif
}
topimg {
  width = 200
  file.pic2 = fileadmin/logo2.gif
}
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The objects in the highlighted lines contain the reserved word "file" and the properties are always of data type "resource".

Using constants

When a TypoScript Template is parsed by the TYPO3 CMS, constants are replaced, as one would perform any ordinary string replacement. Constants are used in the "Setup" field by placing them inside curly braces and prepending them with a $ sign:

{$bgCol}
{$topimg.width}
{$topimg.file.pic2}
{$file.toplogo}
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Only constants, which are actually defined in the Constants field or an included constants.typoscript file, are substituted.

Constants from included TypoScript files are also substituted. All TypoScript constants are combined before the TypoScript Setup configuration is resolved.

A systematic naming scheme should be used for constants. As "paths" can be defined, it's also possible to structure constants and prefix them with a common path segment. This makes reading and finding of constants easier.

Example

EXT:my_sitepackage/Configuration/TypoScript/setup.typoscript 
page = PAGE
page {
  typeNum = 0
  bodyTag = <body class="{$tx_my_sitepackage.bgCol}">
  10 = IMAGE
  10.file = {$tx_my_sitepackage.file.toplogo}
}
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For the above example to work, the constants from the last example have to be defined in the constants field or a file called constants.typoscript:

EXT:my_sitepackage/Configuration/TypoScript/constants.typoscript 
tx_my_sitepackage {
  bgCol = bg-primary
  file.toplogo = EXT:my_sitepackage/Resources/Public/Images/Logo.png
}
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Screenshot of the TypoScript record editor showing the Constants and Setup fields

The fields Constants and Setup in the TypoScript backend record

You can use the sub module Site Management > TypoScript > Active TypoScript to display which values are assigned to constants. The constant key is displayed in red, the replacement in green:

Screenshot of the Active TypoScript with constants substituted

Changed in version 12.0

The TypoScript management tools are now found in backend module Site Management > TypoScript. It was formerly found in "Page > Template".

The submodule Active TypoScript was renamed from "TypoScript Object Browser".