This particular opera is by Christoph Willibald Gluck, not Der Barbier von Bagdad. That opera was written by the man who provided  a libretto in Chimne.
Iphignie en Tauride ("Iphigenia in Tauris") is a 1779 opera by Christoph Willibald Gluck in four acts. 
Der Barbier von Bagdad ("The Barber of Baghdad") is a comic opera in two acts by Peter Cornelius to a German libretto by the composer, based on "The Tale of the Tailor" and "The Barbers Stories of his Six Brothers" in "One Thousand and One Nights". 
 His most famous work is "Iphignie en Tauride", his first libretto, set by Gluck after the composer had initially rejected it. 
 It takes the form of a "tragdie (lyrique)" in three acts, with a libretto by Nicolas-Franois Guillard. 
