ef core may to many update with extra filed - asp.net-core

Question

My mode class:
public class AccountCustomer
{
public bool IsMain { get; set; }
public int AccountId { get; set; }
public Account Account { get; set; }
public int CustomerId { get; set; }
public Customer Customer { get; set; }
}
public class Account
{
public int Id { get; set; }
public strig No{ get; set; }
..other fields
public ICollection<AccountCustomer> AccCustomer { get; set; } = new List<AccountCustomer>();
}
public class Customer
{
public int Id { get; set; }
public strig Name{ get; set; }
..other fields
public ICollection<AccountCustomer> AccCustomer { get; set; } = new List<AccountCustomer>();
}
I found soluton here and i have implemented same later i found that it is for without extra column
Many to many ef core updaate
Please let meknow how to do update... Am using latest ef 5 preview
My code :
_context.Set<AccountCustomer>().UpdateLinks(ac => ac.AccountId, account.Id,
ac => ac.CustomerId, account.AccCustomer .Select(ac => ac.CustomerId));

Answer 1

Codes of ManyToMany Update Extensions
Remove the unselected item and add new item to list.
public static class Extensions
{
public static void TryUpdateManyToMany<T, TKey>(this DbContext db, IEnumerable<T> currentItems, IEnumerable<T> newItems, Func<T, TKey> getKey) where T : class
{
db.Set<T>().RemoveRange(currentItems.ExceptThat(newItems, getKey));
db.Set<T>().AddRange(newItems.ExceptThat(currentItems, getKey));
}
private static IEnumerable<T> ExceptThat<T, TKey>(this IEnumerable<T> items, IEnumerable<T> other, Func<T, TKey> getKeyFunc)
{
return items
.GroupJoin(other, getKeyFunc, getKeyFunc, (item, tempItems) => new { item, tempItems })
.SelectMany(t => t.tempItems.DefaultIfEmpty(), (t, temp) => new { t, temp })
.Where(t => ReferenceEquals(null, t.temp) || t.temp.Equals(default(T)))
.Select(t => t.t.item);
}
}
Codes of Update ViewModel
The update view pass it to action via request.
public class AccountCustomerVM
{
public bool IsMain { get; set; }
public Account Account { get; set; }
public List<int> Customers { get; set; }
}
Codes of Update Action
[HttpPut]
public IActionResult Update(AccountCustomerVM accountCustomerVM)
{
var model = _context.Accounts.Include(x => x.AccCustomer).FirstOrDefault(x => x.Id == accountCustomerVM.Account.Id);
_context.TryUpdateManyToMany(model.AccCustomer, accountCustomerVM.Customers
.Select(x => new AccountCustomer
{
IsMain = accountCustomerVM.IsMain,
CustomerId = x,
AccountId = accountCustomerVM.Account.Id
}), x => x.CustomerId);
_context.SaveChanges();
return Ok();
}