Foreign Key links - "Restrict is specified" error

[Dave Addey]

Hi all,

I¹m trying to get a Foreign Key link to work, to link together a list of
Tracks and a list of Playlists (read in from iTunes).  But I¹m having some
problems.  Here¹s the background.

I¹m reading in the iTunes XML library.  I get the Tracks first, then the
Playlists, with each of their PlaylistTracks (showing how tracks are used in
a playlist).

Each Track has a unique integer ID, and so does each Playlist.  I have a
third table, ³vPlaylistTracks², which links Playlists and Tracks together.

In the constructor of both my vTracks table and my vPlaylists I have a call
to create the UniqueID:

  UniqueID = New VULong("UniqueID", EVFlag.fUnique + EVFlag.fIndexed)

(Both tables have a property called ³UniqueID as VULong²)
  
In my joining table, I have:

  Name = "PlaylistTracks"
  
  PlaylistUniqueIDPtr = New VULong("PlaylistUniqueIDPtr", EVFlag.fIndexed +
EVFlag.fNullable)
  TrackUniqueIDPtr = New VULong("TrackUniqueIDPtr", EVFlag.fIndexed +
EVFlag.fNullable)
  

In my Database constructor, I have:

  VDatabase(EVStorageType.kDefault)
  
  vTracks = New vTracksTable
  vPlaylists = New vPlaylistsTable
  vPlaylistTracks = New vPlaylistTracksTable
  
  vPT_PlaylistUniqueIDLink = CreateForeignKeyLink("PT_PlaylistUniqueIDLink",
vPlaylists.UniqueID, vPlaylistTracks.PlaylistUniqueIDPtr,
EVOnDelete.kSetNull, EVOnUpdate.kCascade, false)
  vPT_TrackUniqueIDLink = CreateForeignKeyLink("PT_TrackUniqueIDLink",
vTracks.UniqueID, vPlaylistTracks.TrackUniqueIDPtr, EVOnDelete.kSetNull,
EVOnUpdate.kCascade, false)
  
I can add Tracks and Playlists to their tables with no problems.  But when I
try and add a PlaylistTrack to the vPlaylistTracks table, I get an error.

Here¹s what I am doing:

  Dim newRecID as integer
  LibraryDB3.vPlaylistTracks.SetBlank(EVValueAccess.forAdd)
  LibraryDB3.vPlaylistTracks.PlaylistUniqueIDPtr.Value = inPlaylistID
  LibraryDB3.vPlaylistTracks.TrackUniqueIDPtr.Value = inTrackID
  newRecID = LibraryDB3.vPlaylistTracks.AddRecord
  
The AddRecord call raises a Vexception error:

³Restrict is specified.  Dropping is un available till constraints exist.²

What does this error mean?  What have I done wrong?

Dave.