How can i get a variable value (The value of a field in the current record) into the DocumentOpen statement?

If I put a hardcoded value in it works fine but I cannot seem to insert a variable value into the statement.

DocumentOpen("ProcessHistoryView/?BuildNumber=1234") works fine but

DocumentOpen("ProcessHistoryView/?BuildNumber=FieldName") does not, even if FieldName is replaced by a GetVar statement (ProcessHistoryView is a Quick Report).

Sorry for the late reply. 

DocumentOpen(concat("ProcessHistoryView/?BuildNumber=",FieldName")) 

DocumentOpen need a text string, so if you want it to be variable you need to build a text string that is variable the normal way.

I think you have gone a little "blind" here and can't see the forest for all the trees ;-)

DocumentOpen("ProcessHistoryView/?BuildNumber=FieldName") will not work "twice" over.

1. The filter will be BuildNumber=Fieldname were Fieldname is a fixed string.
2. Because the filter is BuildNumber=Fieldname it is illegal too as strings need to be quoted i.e BuildNumber="FieldName".

if you would want to build a filter (that is what this is) where you wanted to transfer a string/text you would have to do it this way.

DocumentOpen(concat("ProcessHistoryView/?BuildNumber=/'",FieldName"/'))

this way you get it escaped so your result will contain " " around the value.