Add much stuff for rewrite

src/db/errors.rs

@@ -11,6 +11,7 @@ pub enum DatabaseError {
 	NotFound,
 	Protected,
 	UpdateError(diesel::result::Error),
+	Unknown,
 }
 
 impl DatabaseError {
@@ -47,6 +48,7 @@ impl From<&DatabaseError> for String {
 			DatabaseError::DeleteError => String::from("error on deleting from database"),
 			DatabaseError::Protected => String::from("model is protected"),
 			DatabaseError::UpdateError(_) => String::from("error on updating the model"),
+			DatabaseError::Unknown => String::from("unknown error"),
 		}
 	}
 }