public List <Contact> GetAllContacts()
{
using (_context = new ContactsContext2())
{
return(_context.Contacts.ToList());
}
}
public Contacts2()
{
using (_context = new ContactsContext2())
{
//context.Database.EnsureDeleted();
// Create database, if needed
_context.Database.EnsureCreated();
}
}
public int AddContact(Contact contact)
{
using (_context = new ContactsContext2())
{
_context.Contacts.Add(contact);
_context.SaveChanges();
var c = _context.Entry(contact);
return(c.Entity.ID);
}
}
public void DeleteContact(int id)
{
using (_context = new ContactsContext2())
{
var contact =
_context.Contacts.Include(c => c.Notes).First(c => c.ID == id);
_context.Contacts.Remove(contact);
_context.SaveChanges();
}
}
public Contact GetContact(int id)
{
Contact contact = null;
using (_context = new ContactsContext2())
{
contact =
_context.Contacts.Include(c => c.Notes).First(c => c.ID == id);
}
return(contact);
}
public void UpdateContact(Contact contact)
{
using (_context = new ContactsContext2())
{
// Fetch current version in DB
var contactToUpdate =
_context.Contacts.Include(c => c.Notes).First(c => c.ID == contact.ID);
// Update properties of the parent
_context.Entry(contactToUpdate).CurrentValues.SetValues(contact);
// Clone contactNotes to mitigate:
// "System.InvalidOperationException: Collection was modified after the enumerator was instantiated."
List <Note> contactNotesClone = new List <Note>();
foreach (Note n in contactToUpdate.Notes)
{
contactNotesClone.Add(n);
}
// Remove or update child collection items
foreach (var contactNote in contactNotesClone)
{
// ... Fetch corresponding note from "contact" update
var note = contact.Notes.SingleOrDefault(n => n.ID == contactNote.ID);
if (note != null)
{
// .. Present in "contact" update: write the updated "note" value to DB
_context.Entry(contactNote).CurrentValues.SetValues(note);
}
else
{
// .. Not present in "contact" update: delete this note from DB
_context.Remove(contactNote);
}
}
// Add the new items
foreach (var note in contact.Notes)
{
if (contactNotesClone.All(n => n.ID != note.ID))
{
// .. Not present in DB: add as a new "note"
contactToUpdate.Notes.Add(note);
}
}
// OK: Refresh the database
_context.SaveChanges();
}
}
