linqkit

I'm using LinqKit library which allows combining expressions on the fly. This is a pure bliss for writing Entity Framewok data acess layer because several expressions can optionally be reused and combined, which allows both for readable and efficient code. Consider following piece of code: private static readonly Expression<Func<Message, int, MessageView>> _selectMessageViewExpr = ( Message msg, int requestingUserId ) => new MessageView { MessageID = msg.ID, RequestingUserID = requestingUserId, Body = ( msg.RootMessage == null ) ? msg.Body : msg.RootMessage.Body, Title = ( ( msg.RootMessage ==

I'm beginning to use LinqKit 's PredicateBuilder to create predicate's with OR conditions which is not possible with Linq expressions. The problem I'm facing is if I begin with PredicateBuilder.True<MyEntity>() it returns all rows and if I begin with PredicateBuilder.False<MyEntity>() it returns non rows , apart from what expressions I use! look at the code below: var pre = PredicateBuilder.True<MyEntity>(); pre.And(m => m.IsActive == true); using (var db = new TestEntities()) { var list = db.MyEntity.AsExpandable().Where(pre).ToList(); dataGridView1.DataSource = list; } It should return the

Given a simple parent/child class structure. I want to use linqkit to apply a child lambda expression on the parent. I also want the Lambda expression to be provided by a utility method. public class Foo { public Bar Bar { get; set; } } public class Bar { public string Value { get; set; } public static Expression<Func<Bar, bool>> GetLambdaX() { return c => c.Value == "A"; } } ... Expression<Func<Foo, bool>> lx = c => Bar.GetLambdaX().Invoke(c.Bar); Console.WriteLine(lx.Expand()); The above code throws System.InvalidCastException: Unable to cast object of type 'System.Linq.Expressions

I'm using LINQ to Entities for Entity Framework objects in my Data Access Layer. My goal is to filter as much as I can from the database, without applying filtering logic to in-memory results. For that purpose Business Logic Layer passes a predicate to Data Access Layer. I mean Func<MyEntity, bool> So, if I use this predicate directly, like public IQueryable<MyEntity> GetAllMatchedEntities(Func<MyEntity, Boolean> isMatched) { return qry = _Context.MyEntities.Where(x => isMatched(x)); } I'm getting the exception [System.NotSupportedException] --- {"The LINQ expression node type 'Invoke' is not