CObject ViewHelper <f:cObject> 

Use data from a plugin in TypoScript 

By using the data property you can forward data provided by the controller to the TypoScript object doing the actual rendering:

<f:cObject
    typoscriptObjectPath="lib.customHeader"
    data="{myplugin.article}"
    currentValueKey="title"
/>

The same can also be done in the inline notation.

{article -> f:cObject(typoscriptObjectPath: 'lib.customHeader', currentValueKey: 'title')}

The TypoScript could for example look like this:

lib.customHeader = COA
lib.customHeader {
   10 = TEXT
   10.field = author
   20 = TEXT
   20.current = 1
}

When passing an object with {data}, the properties of the object are accessible with .field in TypoScript. If only a single value is passed or the currentValueKey is specified, .current = 1 can be used in the TypoScript.

Use data from a TypoScript ContentObject 

As an example of a more advanced use case, the cObject viewhelper can pass content data from a Fluid template to a content object defined in TypoScript. The following example demonstrates this with a user counter. The user counter is in a blog post (the blog post has a count of how many times it has been viewed.)

Add the Viewhelper to your Fluid template. This can be done in 3 different ways. The basic tag syntax:

<f:cObject typoscriptObjectPath="lib.myCounter">{post.viewCount}</f:cObject>

Or a self-closing tag. Data is passed in the data attribute.

<f:cObject typoscriptObjectPath="lib.myCounter" data="{post.viewCount}" />

Or inline notation, which is easy to read and understand (from left to right):

{post.viewCount -> f:cObject(typoscriptObjectPath: 'lib.myCounter')}

Then, add TypoScript (to your TypoScript template) to process this data. In our example below, the stdWrap attribute current works like a switch: if set to 1, it contains the value that was passed to the TypoScript object from the Fluid template:

lib.myCounter = TEXT
lib.myCounter {
  current = 1
  wrap = <strong>|</strong>
}

This TypoScript snippet outputs the current number of visits in bold.

We can easily modify this TypoScript to output the user counter as an image instead of text:

lib.myCounter = IMAGE
lib.myCounter {
  file = GIFBUILDER
  file {
     10 = TEXT
     10.text.current = 1
  }
}

{post -> f:cObject(typoscriptObjectPath: 'lib.myCounter')}

lib.myCounter = COA
lib.myCounter {
  10 = TEXT
  10.field = title
  20 = TEXT
  20.field = viewCount
  wrap = (<strong>|</strong>)
}

{post -> f:cObject(typoscriptObjectPath: 'lib.myCounter', currentValueKey: 'viewCount')}

lib.myCounter = COA
lib.myCounter {
  10 = TEXT
  10.field = title
  20 = TEXT
  20.current = 1
  wrap = (<strong>|</strong>)
}

Migration: Use the f:render.contentArea ViewHelper 

If you are using the page-content data processor to display the content elements of a PAGEVIEW, switch to the Render.contentArea ViewHelper <f:render.contentArea> on dropping TYPO3 v13 support:

- <f:for each="{myContent.left.records}" as="contentElement">
-     <f:cObject
-         typoscriptObjectPath="{contentElement.mainType}"
-         table="{contentElement.mainType}"
-         data="{contentElement}"
-     />
- </f:for>

+ <f:render.contentArea contentArea="{myContent.left}" />

Variable {contentElement.mainType} already contains the correct TypoScript path to the TypoScript top-level object tt_content.

The table storing the content elements is also called tt_content, so we can use the same variable here. Variable contentElement will already contain the Record object containing the data needed to render the content element with the CObject ViewHelper.