[TYPO3-english] Flexform questions

[Robert Wildling]

Hi,

A Flexform shall eventually have 3 fields, one showing after the other 
as soon as the previous one has a value.

This is step one:

<teaserPID>
	<TCEforms>
		<onChange>reload</onChange>
		<label>Select Page (pid)</label>
		<config>
			<type>input</type>
		</config>
	</TCEforms>
</teaserPID>

<infoOne>
	<TCEforms>
		<displayCond>FIELD:teaserPID:=:0</displayCond>
		<label>Save to enable new fileds</label>
		<config>
			<type>none</type>
		</config>
	</TCEforms>
</infoOne>


My question here is:

1. At the moment, infoOne evaluates against a value of 0 of teaserPID 
and decides upon that whether to display or not. But what if teaserPID 
has no value at all? I tried:

FIELD:teaserPID:IN:0,NULL,''

but that just doesn't work, and even though I studied the 
http://typo3.org/documentation/document-library/core-documentation/doc_core_api/4.2.0/view/4/2/ 
I couldn't find a solution. What am I supposed to do here?


The next step would be to show a field that reads the contents from the 
table with the pid given in teaserPID in form of a database relation (an 
empty select box next to a selectbox with a list of content elements to 
choose from). Here I am totally stuck. The only entry in the Core 
documentation that can be found when searching for database relation is 
under allowNonIdValues ...

I have a feeling that a script is needed like in tt_news, but I can 
nowhere find a description of how and why and some hints etc...

Can anybody point please me to a tutorial?

Any help is greatly appreciated!
Thanks!

Regards,
Robert