# Introduction to Fluid¶

Fluid is TYPO3’s default rendering engine but can also be used in a standalone PHP project. The Fluid source code is being developed as an independent project outside of the TYPO3 Core.

Fluid is based on XML. You can use HTML markup in Fluid, but you can do much more with Fluid, such as use conditions, variables or custom ViewHelpers which are PHP components.

## Example Fluid snippet¶

This is how a simple Fluid snippet could look like:

<h4>This is your headline</h4>
<p>
<f:if condition="{myExpression}">
<f:then>
{somevariable}
</f:then>
<f:else>
{someothervariable}
</f:else>
</f:if>
</p>


The resulting HTML may look like this:

<h4>This is your headline</h4>
<p>This is the content of variable "somevariable"</p>


The above Fluid snippet contains:

ViewHelpers:

The XML elements that start with f: like <f:if> etc. are standard ViewHelpers. It is also possible to define custom ViewHelpers, for example <foo:bar foo="bar">. A corresponding file ViewHelpers/BarViewHelper.php with the methods initializeArguments and render contains the HTML generation logic. ViewHelpers are Fluid components which make a function call to PHP from inside of a template. TYPO3 adds some more ViewHelpers for TYPO3 specific functionality. And, you can write your own.

ViewHelpers can do simple processing such as remove spaces with the spaceless Viewhelper or create a link as is done in the TYPO3 Fluid Viewhelper link.page.

Object Accessors:
Fluid can access variables that have been defined. Just use braces and the name of the variable: {somevariable}. In Fluid, these placeholders are called Object Accessors.
Conditions:
The conditions are supplied here by the if / then / else ViewHelpers.

## Directory structure¶

In your extension, the following directory structure should be used for Fluid files:

── Resources
└── Private
├── Layouts
├── Partials
└── Templates


This directory structure is the convention used by TYPO3 CMS. When using Fluid outside of TYPO3 CMS you can use any folder structure you like.

If you are using Extbase controller actions in combination with Fluid, Extbase defines how files and directories should be named within these directories. Extbase uses sub directories located within the “Templates” directory to group templates by controller name and the filename of templates to correspond to a certain action on that controller (see Template creation by example).

└── Resources
└── Private
└── Templates
└── Blog
├── List.html (for Blog->list() action)
└── Show.html (for Blog->show() action)


If you don’t use Extbase you can still use this convention, but it is not a requirement to use this structure to group templates into logical groups, such as “Page” and “Content” to group different types of templates.

In Fluid, the location of these paths is defined with \TYPO3Fluid\Fluid\Core\Rendering\RenderingContext->setTemplatePaths().

TYPO3 provides the possibility to set the paths using TypoScript.

### Templates¶

The template contains the main Fluid template. When using a layout (this is optional), you must define the sections that are referenced by the layout.

### Layouts¶

optional

Layouts serve as a wrapper for a web page or a specific block of content. If using Fluid for a sitepackage, a single layout file will often contain multiple components such as your sites menu, footer, and any other items that are reused throughout your website.

Templates can be used with or without a Layout.

• With a Layout anything that’s not inside a section is ignored. When a Layout is used, the Layout determines which sections will be rendered from the template through the use of <f:render> in the Layout file.
• Without a Layout anything that’s not inside a section is rendered. You can still use sections of course, but you then must use f:render in the template file itself, outside of a section, to render a section.

### Partials¶

optional

Partials are a Fluid component. Partials can be used as reusable components from within a template.

## Example: Using Fluid to create a theme¶

This example was taken from the example extension for Sitepackage Tutorial and reduced to a very basic example.

The Sitepackage Tutorial walks you through the creation of a sitepackage (theme) using Fluid. In our simplified example, the overall structure of a page is defined by a layout “Default”. We show an example of a three column layout. Further templates can be added later, using the same layout.

Resources/
└── Private
├── Layouts
│   └── Page
│       └── Default.html
├── Partials
│   └── Page
│       └── Jumbotron.html
└── Templates
└── Page
└── ThreeColumn.html


Set the Fluid paths with TypoScript using FLUIDTEMPLATE

lib.dynamicContent = COA
lib.dynamicContent {
10.colPos.cObject = TEXT
10.colPos.cObject {
field = colPos
ifEmpty.cObject = TEXT
ifEmpty.cObject {
value.current = 1
ifEmpty = 0
}
}
20 = CONTENT
20 {
table = tt_content
select {
orderBy = sorting
where = colPos={register:colPos}
where.insertData = 1
}
}
90 = RESTORE_REGISTER
}

page = PAGE
page {
// Part 1: Fluid template section
10 = FLUIDTEMPLATE
10 {
templateName = Default
templateRootPaths {
0 = EXT:site_package/Resources/Private/Templates/Page/
}
partialRootPaths {
0 = EXT:site_package/Resources/Private/Partials/Page/
}
layoutRootPaths {
0 = EXT:site_package/Resources/Private/Layouts/Page/
}
}
}


Resources/Private/Layouts/Page/Default.html:

<f:render section="Header" />
<f:render section="Main" />
<f:render section="Footer" />


Resources/Private/Templates/Page/ThreeColumn.html:

  1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 

• The template uses the layout “Default”. It must then define all sections that the layout requires: “Header”, “Main” and “Footer”.
• In the section “Main”, a partial “Jumbotron” is used.
• The template makes use of column positions (colPos). The content elements for each section on the page will be rendered into the correct div. Find out more about this in Backend layout.
• Again, we are using Object Accessors to access data (e.g. {colPos: '2'}) that has been generated elsewhere.

Resources/Private/Partials/Page/Jumbotron.html:

<div class="jumbotron">
<div class="container">
<h1 class="display-3">Hello, world!</h1>
<p> some text </p>
</div>
</div>


## Further information¶

To get an introduction to the basics of Fluid:

Depending on what you plan to do, you may want to follow one of these comprehensive tutorials:

Once you have successfully completed your fist steps, these references might come in handy: