I need to replace a string (with the replacer node on a document) with a point in the middle for instance "aaa.bbb". I tried all kinds of regular expressions but didn't succeed. Curious enough replacing a string that starts with a point (for instance ".bbb" is very simple.
Using a the string manipulation is not possible because I read the files as documents.
I don't know what exactly you are trying to achieve. If you want to replace "aaa.bbb" with let's says "+++" then you just enter those two terms in the dialog. See the attached workflow for an example.