Troubles with large amount of Code duplication

Question

I have a lot of methods that follow in large parts the same algorithm, and I ideally want to be able to make calls to a generic method that eliminates a lot of code duplication.

I have tons of methods like the ones below, I would optimally want to be able to just call Save<SQLiteLocation>(itemToSave); but i have a great deal of trouble since that the methods SQLiteConnection.Find<T> won't accept an abstract data type like T in generics.

Is there any way to get around this, if i could get it fixed i would save as many as 150 lines of code

Here's my code:

    public bool SaveLocation(ILocation location, ref int primaryKey)
    {
        var dbConn = new SQLiteConnection (dbPath);

        SQLiteLocation itemToSave = new SQLiteLocation ();
        itemToSave.LocationName = location.LocationName;
        itemToSave.Latitude = location.Latitude;
        itemToSave.Longitude = location.Longitude;
        itemToSave.PrimaryKey = location.PrimaryKey;

  ----------------------------------------------------------------------------------------

        SQLiteLocation storedLocation = dbConn.Find<SQLiteLocation>
                                        (x => x.PrimaryKey == location.PrimaryKey);

        if (storedLocation != null)
        {
            dbConn.Update(itemToSave);
            return true;
        }

        else if (storedLocation == null)
        {
            dbConn.Insert(itemToSave);
            primaryKey = itemToSave.PrimaryKey;
            return true;
        }
        return false;
    }

And here another method see how the code in both methods below my dashed line is basically the same thing

    public bool SaveInvitation(IInvitation invitation, ref int primaryKey)
    {
        var dbConn = new SQLiteConnection(dbPath);

        SQLiteInvitation itemToSave = new SQLiteInvitation ();
        itemToSave.GroupName = invitation.GroupName;
        itemToSave.InviterName = invitation.InviterName;
        itemToSave.ParseID = invitation.ParseID;
        itemToSave.GroupParseID = invitation.GroupParseID;
        itemToSave.PrimaryKey = invitation.PrimaryKey;

---------------------------------------------------------------------------------------

        SQLiteInvitation storedInvitation = dbConn.Find<SQLiteInvitation> 
                                            (x => x.PrimaryKey == invitation.PrimaryKey);

        if (storedInvitation != null)
        {
            dbConn.Update(itemToSave);
            return true;
        }
        else if (storedInvitation == null)
        {
            dbConn.Insert(itemToSave);
            primaryKey = itemToSave.PrimaryKey;
            return true;
        }
        return false;
    }

Answer 1

Shouldn't you be able to do something like this: Note: ICommonInterface is anything that is common between any allowable classes you would want to use as T. Preferably, looking at your code, an interface or class that exposes the PrimaryKey property.

public bool SaveItem<T>(T item, ref int primaryKey) where T : ICommonInterface, new()
{
    var dbConn = new SQLiteConnection(dbPath);


    T storedItem = dbConn.Find<T>(x => x.PrimaryKey == item.PrimaryKey);

    if (storedItem != null)
    {
        dbConn.Update(item);
        return true;
    }
    else if (storedItem == null)
    {
        dbConn.Insert(item);
        primaryKey = item.PrimaryKey;
        return true;
    }
    return false;
}

EDIT: Added the new() constraint to the method.