[Zope] Passing an instance in a form to a product method

[Ulla Theiss]

Hello List,

I have to pass an instance of a self-defined class within a form to a product method.
I try it in the following way:

<form action="addUploadFile" enctype="multipart/form-data" target="main" method=post>
<input name="doc:instance" value="<dtml-var doc>" type="hidden">
<input name="addFile" value="add File" type="submit">
</form>

But within the method addUploadFile, always the parameter doc is passed as a string (the name of the instance)

Does anybody know, what I have to change, that it works?

Many thanks in advance
Ulla.