Crashing with lots of code duplication

Question

I have many methods that in most cases follow the same algorithm, and ideally I want to be able to make calls to a common method that eliminates a lot of code duplication.

I have many methods like the ones below, I would optimally want to just be able to call Save<SQLiteLocation>(itemToSave); , but I have a lot of problems, since the SQLiteConnection.Find<T> methods will not accept abstract data types such as T in generics.

Is there any way around this, if I could fix it, I would save up to 150 lines of code

Here is 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 shows how the code in both methods below my dashed line is basically the same

  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

For some reason, it threw an unsupported exception when I used:

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

The code below fixed my problems, although thanks for helping everyone, I like this site! In addition, I added one more restriction on T vision, since T should not be an abstract type, and the interface is what I suppose

  private void SaveItem<T>(T item, ref int primaryKey) where T : ISQLiteClass, new() { var dbConn = new SQLiteConnection(dbPath); T storedItem = dbConn.Find<T>(primaryKey); if (storedItem != null) { dbConn.Update(item); } else if (storedItem == null) { dbConn.Insert(item); primaryKey = item.PrimaryKey; } } 

Answer 2

Can't you do something like this: Note. ICommonInterface is something in common between any valid classes that you would like to use as T. Preferably, looking at your code, interface, or class that provides 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 new () constraint for the method.