Thank you very much for your help.

I am not an expert in programming but if someone in addition to my first question would like to know how to avoid double space when one of the fields is empty, I did it like this.

sentence = (record.x_studio_id_type or "") +" "+ (record.x_studio_id_number or "") +" "+ (record.x_studio_first_name or "") +" "+ (record.x_studio_last_name or "")

sentence_without_double_space= " ".join(sentence.split())

record.write({'x_name': sentence_without_double_space})

If someone can tell me if there is a better way I would appreciate your comment.