Recursive Delete not working

[Martin Kirsten]

I have a class with two OneToMany relationships, both marked as CascadeOperations=CascadeOperation.All. The inverse ManyToOne relationships are also marked as CascadeOperations=CascadeOperation.All (QUESTION: is it necessary to mark the inverse relationship?).

Here is a (simplified) version of my model classes:

public class ZoneCollection
{
    [PrimaryKey, AutoIncrement]
    public int Id { get; set; }

    [OneToMany(CascadeOperations=CascadeOperation.All)]
    public List<Room> Rooms { get; set; }

    [OneToMany(CascadeOperations=CascadeOperation.All)]
    public List<TagZone> Zones { get; set; }
}

public class TagZone
{
    [PrimaryKey, AutoIncrement]
    public int Id { get; set; }

    [ForeignKey(typeof(ZoneCollection))]
    public int ZoneCollectionId { get; set; }

    [ManyToOne(CascadeOperations=CascadeOperation.All)]
    public ZoneCollection ZoneCollection { get; set; }
}

public class Room : TagZone
{
    [PrimaryKey, AutoIncrement]
    public int Id { get; set; }

    public string Name { get; set; }
}

When performing a recursive Delete on an instance of TagZoneCollection:

var itemToDelete = Connection.Table<T>().SingleOrDefault (x => x.Guid == guid);
if (itemToDelete != null) {
    Connection.Delete (itemToDelete, recursive: true);
}

I expect that its child Rooms and TagZones will be deleted as well, but they aren't; only the ZoneCollection instance (i.e. the parent) is deleted. I have tracked the issue down to this line in method DeleteAllRecursive() in class WriteOperations:

var value = relationshipProperty.GetValue(element, null);

where value evaluates to null, and the call to

conn.DeleteValueRecursive(value, recursive, objectCache);

therefore does nothing.

Am I doing something wrong?

[Guillermo Gutiérrez]

Recursive delete will delete objects that are already in memory, but it won't access database to load relationships of objects to delete. So, to sum up, replace this line:

var itemToDelete = Connection.Table<T>().SingleOrDefault (x => x.Guid == guid);

With:

var itemToDelete = Connection.FindWithChildren<T>(guid);

And let me know how it goes.

[Martin Kirsten]

Hi Guillermo

Fantastic, that did the trick, thanks!

[Martin Kirsten]

Issue resolved by using FindWithChildren<T>()