Refactoring: LINQ and Lambda Examples

I had migrated a project from .NET 2.0 to .NET 3.5. Guess it's also a good time to test some simple LINQ and Lambda. :)

Example 1: Simple List<A> to List<B>

List<ItBase> items = new List<ItBase>(); List<DBEntityBase> entities = GetDBEntities(typeof(ItBase), ids); foreach (DBEntityBase entity in entities) items.Add((ItBase)entity); becomes List<ItBase> items = new List<ItBase>(); List<DBEntityBase> entities = GetDBEntities(typeof(ItBase), ids); items = entities.ConvertAll<ItBase>(e => (ItBase)e);

Example 2: Return members of List<A> with conditions

List<Attachment> attachments = new List<Attachment>(); foreach (Attachment attachment in this) { if (attachment.AttachmentType == attachmentType) attachments.Add(attachment); } return attachments; becomes List<Attachment> attachments = new List<Attachment>(); return attachments.FindAll(a => a.AttachmentType == attachmentType);

Example 3: from array of int (index) returns List<Y> objects

List<ItBase> items = new List<ItBase>(); foreach (int id in ids) { items.Add(this[id]); } return items; becomes List<ItBase> items = new List<ItBase>(); items.AddRange(from i in ids select this[i]); return items;

Example 4: From List<A> to List<B> but A and B are not inherited classes

List<User> users = new List<User>(); foreach (UserData userData in result) { User user = new User(); user.Email = userData.Email; user.ID = userData.ID; user.Name = userData.Name; users.Add(user); } becomes List<User> users = new List<User>(); users = result.ConvertAll<User>(r => new User { Email = r.Email, ID = r.ID, Name = r.Name, } );