Advanced querying across related entities

OData can also be used to querying for results across related entities.

The example below illustrates how to retrieve all contacts that are party (with a specific role) on an open case (File) where the case has a specific free information (FileInfo) associated with it.

Example:


		string partyRole = "Sagspart"; // The role that the party on the file must have
string infoType = "Belægning"; // The type of information that the file must have
string infoValue = "AF2"; // The value of information that the file information must have
 
var query = from c in context.Contacts
            where c.Files.Any(fc => 
                fc.CustomLabel_Value == partyRole && 
                fc.File.Closed == null && 
                fc.File.Infoes.Any(fi => 
                    fi.CustomLabel_Value == infoType && 
                    fi.Info_Value == infoValue))
            select new Contact
            {
                ID = c.ID,
                Summary = c.Summary
            };
 
// Executing the query
var contacts = new DataServiceCollection<Contact>(query);
 
// Paging thru the results to get them all
while (contacts.Continuation != null)
{
    contacts.Load(context.Execute(contacts.Continuation));
}
 
// Now we have all contacts that are party of an open cases with role partyRole and the case have an information of type infoType with value infoValue
foreach (Contact c in contacts)
    Console.WriteLine(c.ID + " - " + c.Summary);