Hello Juan Dent,
Based on my understanding, the objective is that we are trying to get the
count of a navigation collection without loading the collection from the
data base. If I have misunderstood the question, please feel free to
correct me.
In my opinion, when we access the count from the entity instance's property
as using admin.Department.Count, it always returns the local cached result.
This is the reason why we must call the Load() method firstly before we get
the right number.
To query directly against the database, we need to use LINQ to Entities
query statement. (not the Entity SQL). These query statements can be
written in two kind of ways, the operator-based and the method-based. I
take NorthWind database for example and write the following code snippet. I
also add some comments inline. Hope it is what you are looking for.
using (NorthwindEntities context = new NorthwindEntities())
{
ObjectQuery<Customers> customers = context.Customers;
//Query the server database directly using operator based statement
//return 6 on my side.
var queryWithOperator = from customer in customers
where customer.CustomerID == "ALFKI"
select new
{
customer.Orders.Count
};
Debug.Print(queryWithOperator.First().Count.ToString());
//Query the server database directly using method based statement
//return 6 on my side.
var queryWithMethod = context.Customers.Where(c => c.CustomerID ==
"ALFKI").Select(c => new
{
c.Orders.Count
}
);
Debug.Print(queryWithMethod.First().Count.ToString());
//Query by reading the instance's property when the navigation
collection is not loaded
//return 0 on my side.
Debug.Print(context.Customers.First().Orders.Count.ToString());
//Query by reading the instance's property when the navigation
collection loaded
//return 6 on my side.
if (!context.Customers.First().Orders.IsLoaded)
{
context.Customers.First().Orders.Load();
}
Debug.Print(context.Customers.First().Orders.Count.ToString());
}
Please let me know if my suggestion works for you or not. If you need
future help on this, please feel free to let me know. I will try my best to
follow up.
Have a nice day!
Best regards,
Ji Zhou (
[email protected], remove 'online.')
Microsoft Online Community Support
Delighting our customers is our #1 priority. We welcome your comments and
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