Add album effective_artist filter that falls back to artist when unavailable (Issue 509)

data/data.qrc

@@ -335,5 +335,6 @@
         <file>icons/22x22/user-away.png</file>
         <file>icons/32x32/search.png</file>
         <file>schema/schema-35.sql</file>
+        <file>schema/schema-36.sql</file>
     </qresource>
 </RCC>

data/schema/schema-36.sql

@@ -0,0 +1,7 @@
+ALTER TABLE %allsongstables ADD COLUMN effective_albumartist TEXT;
+
+UPDATE %allsongstables SET effective_albumartist = albumartist;
+
+UPDATE %allsongstables SET effective_albumartist = artist WHERE effective_albumartist = "";
+
+UPDATE schema_version SET version=36;

src/core/database.cpp

@@ -33,7 +33,7 @@
 #include <QVariant>
 
 const char* Database::kDatabaseFilename = "clementine.db";
-const int Database::kSchemaVersion = 35;
+const int Database::kSchemaVersion = 36;
 const char* Database::kMagicAllSongsTables = "%allsongstables";
 
 int Database::sNextConnectionId = 1;

src/core/organiseformat.cpp

@@ -140,13 +140,11 @@ QString OrganiseFormat::TagValue(const QString &tag, const Song &song) const {
   else if (tag == "samplerate")  value = QString::number(song.samplerate());
   else if (tag == "extension")   value = song.url().toLocalFile().section('.', -1, -1);
   else if (tag == "artistinitial") {
-    value = song.albumartist().trimmed();
-    if (value.isEmpty())  value = song.artist().trimmed();
+    value = song.effective_albumartist().trimmed();
     if (!value.isEmpty()) value = value[0].toUpper();
   }
   else if (tag == "albumartist") {
-    value = song.albumartist();
-    if (value.isEmpty()) value = song.artist();
+    value = song.is_compilation() ? "Various Artists" : song.effective_albumartist();
   }
 
   if (replace_the_ && (tag == "artist" || tag == "albumartist"))

src/core/song.cpp

@@ -105,7 +105,7 @@ const QStringList Song::kColumns = QStringList()
     << "art_manual" << "filetype" << "playcount" << "lastplayed" << "rating"
     << "forced_compilation_on" << "forced_compilation_off"
     << "effective_compilation" << "skipcount" << "score" << "beginning" << "length"
-    << "cue_path" << "unavailable";
+    << "cue_path" << "unavailable" << "effective_albumartist";
 
 const QString Song::kColumnSpec = Song::kColumns.join(", ");
 const QString Song::kBindSpec = Prepend(":", Song::kColumns).join(", ");
@@ -588,6 +588,8 @@ void Song::InitFromQuery(const SqlRow& q, bool reliable_metadata, int col) {
   d->cue_path_ = tostr(col + 34);
   d->unavailable_ = q.value(col + 35).toBool();
 
+  // effective_albumartist = 36
+
   #undef tostr
   #undef toint
   #undef tolonglong
@@ -1069,6 +1071,7 @@ void Song::BindToQuery(QSqlQuery *query) const {
 
   query->bindValue(":cue_path", d->cue_path_);
   query->bindValue(":unavailable", d->unavailable_ ? 1 : 0);
+  query->bindValue(":effective_albumartist", this->effective_albumartist());
 
   #undef intval
   #undef notnullintval

src/core/song.h

@@ -187,6 +187,7 @@ class Song {
   const QString& album() const { return d->album_; }
   const QString& artist() const { return d->artist_; }
   const QString& albumartist() const { return d->albumartist_; }
+  const QString& effective_albumartist() const { return d->albumartist_.isEmpty() ? d->artist_ : d->albumartist_; }
   const QString& composer() const { return d->composer_; }
   int track() const { return d->track_; }
   int disc() const { return d->disc_; }

src/library/librarymodel.cpp

@@ -174,7 +174,7 @@ void LibraryModel::SongsDiscovered(const SongList& songs) {
           case GroupBy_Artist:      key = song.artist(); break;
           case GroupBy_Composer:    key = song.composer(); break;
           case GroupBy_Genre:       key = song.genre(); break;
-          case GroupBy_AlbumArtist: key = song.albumartist(); break;
+          case GroupBy_AlbumArtist: key = song.effective_albumartist(); break;
           case GroupBy_Year:
             key = QString::number(qMax(0, song.year())); break;
           case GroupBy_YearAlbum:
@@ -700,7 +700,7 @@ void LibraryModel::InitQuery(GroupBy type, LibraryQuery* q) {
     q->SetColumnSpec("DISTINCT genre");
     break;
   case GroupBy_AlbumArtist:
-    q->SetColumnSpec("DISTINCT albumartist");
+    q->SetColumnSpec("DISTINCT effective_albumartist");
     break;
   case GroupBy_None:
     q->SetColumnSpec("%songs_table.ROWID, " + Song::kColumnSpec);
@@ -742,7 +742,7 @@ void LibraryModel::FilterQuery(GroupBy type, LibraryItem* item, LibraryQuery* q)
     q->AddWhere("genre", item->key);
     break;
   case GroupBy_AlbumArtist:
-    q->AddWhere("albumartist", item->key);
+    q->AddWhere("effective_albumartist", item->key);
     break;
   case GroupBy_FileType:
     q->AddWhere("filetype", item->metadata.filetype());
@@ -854,7 +854,7 @@ LibraryItem* LibraryModel::ItemFromSong(GroupBy type,
   case GroupBy_Composer:                      item->key = s.composer();
   case GroupBy_Genre: if (item->key.isNull()) item->key = s.genre();
   case GroupBy_Album: if (item->key.isNull()) item->key = s.album();
-  case GroupBy_AlbumArtist: if (item->key.isNull()) item->key = s.albumartist();
+  case GroupBy_AlbumArtist: if (item->key.isNull()) item->key = s.effective_albumartist();
     item->display_text = TextOrUnknown(item->key);
     item->sort_text = SortTextForArtist(item->key);
     break;

src/widgets/osd.cpp

@@ -322,7 +322,7 @@ QString OSD::ReplaceVariable(const QString& variable, const Song& song) {
   } else if (variable == "%title%") {
     return song.PrettyTitle();
   } else if (variable == "%albumartist%") {
-    return song.albumartist();
+    return song.effective_albumartist();
   } else if (variable == "%year%") {
     return song.PrettyYear();
   } else if (variable == "%composer%") {