Typo3, output alternative text of image in page/resources/media - typo3

Question

I use fcObject to output a header image, the image is configured in page/resources/media:
<f:cObject typoscriptObjectPath="lib.headerimage" />
lib.headerimage = IMAGE
lib.headerimage {
file {
# width = 550
# height = 126
import {
data = levelmedia: -1, slide
# wrap = uploads/media/|
# listNum = 0
listNum = rand
}
treatIdAsReference = 1
required = 1
}
altText.data = page: title
# wrap = <div id="keyvisual">|</div>
}
The above code doesn't output the alternative text of the image unfortunately, at the moment it takes the page title as alt text, and I can't figure out how to access the field "alternative".
I could use a viewhelper to output the image, like here:
<f:for each="{data.media}" as="file">
<f:image image="{file}"/>
</f:for>
The benefit of using the image viewhelper is that it gives me the alt text of the image.
I prefer to use the lib though. I just can't figure out how to access the data of the image field "alternative" in typoscript.

Answer 1

You can use FILES to get the expected result:
lib.headerimage = FILES
lib.headerimage {
references {
data = levelmedia: -1, slide
listNum = rand
}
renderObj = IMAGE
renderObj {
file.import.dataWrap = {file:current:storage}:{file:current:identifier}
altText.data = file:current:alternative
}
}
Source: This example was taken from the TypoScript Reference.

Answer 2

You used the wrong field page:title. Use file:current:alternative instead.
lib.headerimage = IMAGE
lib.headerimage {
file {
import {
data = levelmedia: -1, slide
listNum = rand
}
treatIdAsReference = 1
required = 1
}
altText.data = file:current:alternative
}