linq-expressions

I'm dynamically building linq queries for nHibernate. Due to dependencies, I wanted to cast/retrieve the typed expression at a later time, but I have been unsuccessfull so far. This is not working (the cast is supposed to happen elsewhere): var funcType = typeof (Func<,>).MakeGenericType(entityType, typeof (bool)); var typedExpression = (Func<T, bool>)Expression.Lambda(funcType, itemPredicate, parameter); //Fails This is working: var typedExpression = Expression.Lambda<Func<T, bool>>(itemPredicate, parameter); Is it possible to get the 'encapsulated' typed expression from a LambdaExpression?

I've had a look at other questions similar to this one but I couldn't find any workable answers. I've been using the following code to generate unique keys for storing the results of my linq queries to the cache. string key = ((LambdaExpression)expression).Body.ToString(); foreach (ParameterExpression param in expression.Parameters) { string name = param.Name; string typeName = param.Type.Name; key = key.Replace(name + ".", typeName + "."); } return key; It seems to work fine for simple queries containing integers or booleans but when my query contains nested constant expressions e.g. // Get

im using Entity Framework designer first and I need to create custom Model Objects starting from the db objects. I don't want to use IEnumerable cause it will query too many fields. The goal is to remove the inner select within this function: using (var db = new dbEntities()) { var departments= db.departments .Include(p => p.employee) .Where(...) .Select(p => new CustomDepartmentModel() { ID = p.ID, Employees = p.employee .Select(q => new CustomEmployeeModel() { ID = q.ID, Name= q.Name }).ToList() }); return departments.ToList(); } by using this function: public static IQueryable

Consider a class that can be used as a member of multiple other classes: class Customer { public string FirstName {get;set;} public string LastName {get;set;} } // Both "Order" and "Profile" have a "Customer" property class Order { public Customer Customer {get;set;} } class Profile { public Customer Customer {get;set;} } I want to define a method that makes a checker for an object associated with a Customer . If I want an in-memory checker, I do it like this: static Func<T,bool> Check<T>(Func<T,Customer> conv, string first, string last) { return obj => conv(obj).FirstName == first && conv(obj

I'm building an event handler which will work similarly to how aggregates behave in event sourced systems. What I'm trying to achieve can be done in ways as documented here Other references I've looked into are the Marten source code and Greg Young's m-r. I want to achieve the same with Expression Trees. In essence, I want my aggregate implementation to dynamically execute events passed to it if it has a Handle method which accepts that event as a parameter. First I have my events abstract class Event { } class Event1 : Event { } class Event2 : Event { } I have my aggregate implementation