Fix bug 1316979 by making the authors relation viewonly

Fixes: https://launchpad.net/bugs/1316979

openlp/plugins/songs/forms/songmaintenanceform.py

@@ -400,7 +400,7 @@ class SongMaintenanceForm(QtGui.QDialog, Ui_SongMaintenanceDialog, RegistryPrope
         """
         Merges two authors into one author.
 
-        :param old_author:  The object, which was edited, that will be deleted
+        :param old_author: The object, which was edited, that will be deleted
         """
         # Find the duplicate.
         existing_author = self.manager.get_object_filtered(
@@ -415,11 +415,9 @@ class SongMaintenanceForm(QtGui.QDialog, Ui_SongMaintenanceDialog, RegistryPrope
         # Find the songs, which have the old_author as author.
         songs = self.manager.get_all_objects(Song, Song.authors.contains(old_author))
         for song in songs:
-            # We check if the song has already existing_author as author. If
-            # that is not the case we add it.
-            if existing_author not in song.authors:
-                song.authors.append(existing_author)
-            song.authors.remove(old_author)
+            for author_song in song.authors_songs:
+                song.add_author(existing_author, author_song.author_type)
+                song.remove_author(old_author, author_song.author_type)
             self.manager.save_object(song)
         self.manager.delete_object(Author, old_author.id)
 

openlp/plugins/songs/lib/__init__.py

@@ -390,12 +390,12 @@ def clean_song(manager, song):
     verses = SongXML().get_verses(song.lyrics)
     song.search_lyrics = ' '.join([clean_string(verse[1]) for verse in verses])
     # The song does not have any author, add one.
-    if not song.authors and not song.authors_songs:  # Need to check both relations
+    if not song.authors_songs:
         name = SongStrings.AuthorUnknown
         author = manager.get_object_filtered(Author, Author.display_name == name)
         if author is None:
             author = Author.populate(display_name=name, last_name='', first_name='')
-        song.authors.append(author)
+        song.add_author(author)
     if song.copyright:
         song.copyright = CONTROL_CHARS.sub('', song.copyright).strip()
 

openlp/plugins/songs/lib/db.py

@@ -114,6 +114,33 @@ class Song(BaseModel):
         """
         self.sort_key = get_natural_key(self.title)
 
+    def add_author(self, author, author_type=None, ignore_type=False):
+        """
+        Add an author to the song if it not yet exists
+
+        :return: True if the author has been added successfully. False if it was already there.
+        """
+        for author_song in self.authors_songs:
+            if author_song.author == author and (ignore_type or author_song.author_type == author_type):
+                return False
+        new_author_song = AuthorSong()
+        new_author_song.author = author
+        new_author_song.author_type = author_type
+        self.authors_songs.append(new_author_song)
+        return True
+
+    def remove_author(self, author, author_type=None, ignore_type=False):
+        """
+        Remove an existing author from the song
+
+        :return: True if the author has been removed successfully. False if it could not be found.
+        """
+        for author_song in self.authors_songs:
+            if author_song.author == author and (ignore_type or author_song.author_type == author_type):
+                self.authors_songs.remove(author_song)
+                return True
+        return False
+
 
 class Topic(BaseModel):
     """
@@ -283,9 +310,10 @@ def init_schema(url):
     mapper(Book, song_books_table)
     mapper(MediaFile, media_files_table)
     mapper(Song, songs_table, properties={
-        # Use the authors_songs relation when you need access to the 'author_type' attribute.
+        # Use the authors_songs relation when you need access to the 'author_type' attribute
+        # or when creating new relations
         'authors_songs': relation(AuthorSong, cascade="all, delete-orphan"),
-        'authors': relation(Author, secondary=authors_songs_table),
+        'authors': relation(Author, secondary=authors_songs_table, viewonly=True),
         'book': relation(Book, backref='songs'),
         'media_files': relation(MediaFile, backref='songs', order_by=media_files_table.c.weight),
         'topics': relation(Topic, backref='songs', secondary=songs_topics_table)

openlp/plugins/songs/lib/foilpresenterimport.py

@@ -343,7 +343,7 @@ class FoilPresenter(object):
                 author = Author.populate(display_name=display_name, last_name=display_name.split(' ')[-1],
                                          first_name=' '.join(display_name.split(' ')[:-1]))
                 self.manager.save_object(author)
-            song.authors.append(author)
+            song.add_author(author)
 
     def _process_cclinumber(self, foilpresenterfolie, song):
         """

openlp/plugins/songs/lib/olpimport.py

@@ -187,7 +187,7 @@ class OpenLPSongImport(SongImport):
                         first_name=author.first_name,
                         last_name=author.last_name,
                         display_name=author.display_name)
-                new_song.authors.append(existing_author)
+                new_song.authors.add_author(existing_author)
             if song.book:
                 existing_song_book = self.manager.get_object_filtered(Book, Book.name == song.book.name)
                 if existing_song_book is None:

openlp/plugins/songs/lib/songimport.py

@@ -325,7 +325,7 @@ class SongImport(QtCore.QObject):
                 author = Author.populate(display_name=author_text,
                                          last_name=author_text.split(' ')[-1],
                                          first_name=' '.join(author_text.split(' ')[:-1]))
-            song.authors.append(author)
+            song.authors.add_author(author)
         if self.song_book_name:
             song_book = self.manager.get_object_filtered(Book, Book.name == self.song_book_name)
             if song_book is None:

openlp/plugins/songs/lib/songselect.py

@@ -203,6 +203,6 @@ class SongSelectImport(object):
                 author = Author.populate(first_name=author_name.rsplit(' ', 1)[0],
                                          last_name=author_name.rsplit(' ', 1)[1],
                                          display_name=author_name)
-            db_song.authors.append(author)
+            db_song.authors.add_author(author)
         self.db_manager.save_object(db_song)
         return db_song