Question

Given EF entities defined as follows

class Person { int PersonID; string Name; string Title; }
class ContactType { int TypeID; string TypeString; } // phone # types - mobile, home, work etc.
class PersonContact { int PersonID, int ContactTypeID, string ContactText; bool IsDefault; }

Where a person can have multiple phone #’s and even multiple mobile #’s

Looking for ways to display all Persons in a table structure as follows

PersonID, Name, Title, PrimaryContact, MobileNumber

Where PrimaryContact is the PersonContact Record with IsDefault = true

and

WHERE MobileNumber is “A” PersonContact Record with PersonContact.ContactType = ContactType.TypeID and ContactType.TypeString = “Mobile”

NOTE –

PrimaryContact is a lookup into PersonContact

MobileNumber is ALSO a lookup into PersonContact

They could point to the same PersonContact record or could be different depending on IsDefault = true

ALSO There could be multiple “Mobile” PersonContact records for a person

Answer 1

Try this below.

var result = ctx.Persons
.Select(x => 
new {PersonID = x.PersonID, 
     Name = x.Name,
     Title = x.Title,
     PrimaryContact = x.PersonContacts.FirstOrDefault(y => y.IsDefault == true).Select(t => t.ContactText),
     MobileNumber = x.PersonContacts.FirstOrDefault(z => z.ContactType.TypeString =="Mobile").Select(q => q.ContactText)
     }).ToList();

Sadly i think this might result in a select n + 1 type query 🙁