That sounds like it would help as the fields would be populated with the appropriate value and I would then just need to click the submit button. Also the sequence ID for UserID would be correct each time. But can I somehow use {$view_parameters.var} as the default value in my class definition?
The default template loops through the class attributes ( using attribute_edit_gui) picking up their properties, including default values on the way.
Or maybe in can insert {$view_parameters.var} into the template used by attribute_edit_gui ? Which template is that? Or would it probably be easier to just construct an override template using it?
Or would it probably be easier to just construct an override template using it?
Yes, that is the best option. Then you will have full control on the ouput and content class attributes, using edit_view_gui you can display only needed fields rest hide with hidden fields for example.