how do i use group by only on date from datetime in LINQ query

Question

i have this LINQ query

var data = (from orders in db.Orders
        group orders by orders.OrderDate into dateGroup
        select new OrderDateGroup()
        {
            OrderDate = dateGroup.Key,
            OrderCount = dateGroup.Count()
        }).Take(10);

orders.OrderDate is DateTime but i want to group only on the basis of Date

Answer 1

You can use canonical functions:

group orders by EntityFunctions.TruncateTime(orders.OrderDate) into dateGroup

Additional info:

EntityFunctions methods are called canonical functions. And these are a set of functions, which are supported by all Entity Framework providers. These canonical functions will be translated to the corresponding data source functionality for the provider. Canonical functions are the preferred way to access functionality outside the core language, because they keep the queries portable.

You can find all canonical functions here and all Date and Time Canonical Functions here.

Also, don't forget to include System.Data.Objects namepsace from System.Data.Entity.dll.

Note:
If you are using EF6, then you must consider to change EntityFunctions to DbFunctions. And don't forget to include System.Data.Entity namepsace from EntityFramework.dll.