Question

I am new to entity framework.
I need to develop a Linq query based on Orders and Customers.

for eg: string firstName can have any of the three values

1) null
2) Joe
3) like %Joe%’

simailary i need to develop for lastname

My current query is like this

                using (NorthwindEntities ent = new NorthwindEntities())
                {
                    var UsersList = ent.User.Include("Orders").
                                Include("OrderDetails").
                                Include("OrderDetails.Products").
                               .Where(o => (firstName== null || o.firstName== firstName||o.firstName.Contains(firstName)) 
&& (LastName== null || o.LastName== LastName ||o.LastName.contains(LastName) ) 

    }

Is my query is correct. Is any other better option to write linq entity query.

Thanks

Answer 1

You can add conditions to a Queryable object. The conditions will build up until the data query is executed.

var UsersList = ent.User.Include("Orders")
               .Include("OrderDetails")
               .Include("OrderDetails.Products");

if (!string.IsNullOrEmpty(firstName))
   UsersList = UsersList.Where( o => o.firstName.Contains(firstName));

if (!string.IsNullOrEmpty(LastName))
   UsersList = UsersList.Where( o => o.LastName.Contains(LastName));