The specified type member Date is not supported in LINQ to Entities.

On a RIA-enabled Silverlight project I wrote the following LINQ to Entities query in my Domain Service:

public IQueryable<Order> GetOrders() {
var qry = from order in ObjectContext.orders
        where order.OrderDate.Date == DateTime.Now.Date
        select order;
return qry;
}

I want to ignore the time-part of the DateTime so I only compare the date parts but when I ran the query I got this error:

Load operation failed for query 'GetOrders'. The specified type member 'Date' is not supported in LINQ to Entities. Only initializers, entity members, and entity navigation properties are supported.

Solution Part 1 (Works in a viewmodel)

I’ve had this error before and remember I had to check if my date was between a start and end date. Like this:

var qry = from order in ObjectContext.orders
where order.OrderDate >= DateTime.Now.Date
&& order.OrderDate < DateTime.Now.Date.AddDays(1)
select order;
return qry;

But while this works if you build this query on the client (like in a viewmodel), it fails when it’s constructed in a DomainService with the following error:

Load operation failed for query 'GetOrders'. LINQ to Entities does not recognize the method 'System.DateTime AddDays(Double)' method, and this method cannot be translated into a store expression.

Solution Part 2 (Works in DomainService)

Well, the answer is easy enough but not too elegant. We need a helper variable where you add a day to the datetime:

var date2 = DateTime.Now.Date.AddDays(1);
var qry = from order in ObjectContext.orders
     where order.OrderDate >= DateTime.Now.Date
     && order.OrderDate < date2
     select order;
     return qry;