WIP V3: catch proposed duplicate playlist name

Fixes #197

app/models.py

@@ -315,6 +315,17 @@ class Playlists(Base):
 
         self.open = True
 
+    @staticmethod
+    def name_is_available(session: scoped_session, name: str) -> bool:
+        """
+        Return True if no playlist of this name exists else false.
+        """
+
+        return session.execute(
+            select(Playlists)
+            .where(Playlists.name == name)
+        ).first() is None
+
     def rename(self, session: scoped_session, new_name: str) -> None:
         """
         Rename playlist

app/musicmuster.py

@@ -561,7 +561,7 @@ class Window(QMainWindow, Ui_MainWindow):
     ) -> Optional[Playlists]:
         """Create new playlist"""
 
-        playlist_name = self.solicit_playlist_name()
+        playlist_name = self.solicit_playlist_name(session)
         if not playlist_name:
             return None
         playlist = Playlists(session, playlist_name)
@@ -997,7 +997,7 @@ class Window(QMainWindow, Ui_MainWindow):
             dlg.exec()
             template = dlg.playlist
             if template:
-                playlist_name = self.solicit_playlist_name()
+                playlist_name = self.solicit_playlist_name(session)
                 if not playlist_name:
                     return
                 playlist = Playlists.create_playlist_from_template(
@@ -1364,20 +1364,32 @@ class Window(QMainWindow, Ui_MainWindow):
         #     self.tabPlaylist.setCurrentWidget(self.next_track.playlist_tab)
         # self.tabPlaylist.currentWidget().scroll_next_to_top()
 
-    def solicit_playlist_name(self, default: Optional[str] = "") -> Optional[str]:
-        """Get name of playlist from user"""
+    def solicit_playlist_name(
+        self, session: scoped_session, default: str = ""
+    ) -> Optional[str]:
+        """Get name of new playlist from user"""
 
         dlg = QInputDialog(self)
         dlg.setInputMode(QInputDialog.InputMode.TextInput)
         dlg.setLabelText("Playlist name:")
-        if default:
-            dlg.setTextValue(default)
-        dlg.resize(500, 100)
-        ok = dlg.exec()
-        if ok:
-            return dlg.textValue()
-        else:
-            return None
+        while True:
+            if default:
+                dlg.setTextValue(default)
+            dlg.resize(500, 100)
+            ok = dlg.exec()
+            if ok:
+                proposed_name = dlg.textValue()
+                if Playlists.name_is_available(session, proposed_name):
+                    return proposed_name
+                else:
+                    helpers.show_warning(
+                        self,
+                        "Name in use",
+                        f"There's already a playlist called '{proposed_name}'",
+                    )
+                    continue
+            else:
+                return None
 
     def stop(self) -> None:
         """Stop playing immediately"""