entity framework update - entity-framework

Question

i know how to do updates, inserts and deletes with the entityframework but in this case i don't know what to do.
In this case i have 3 tables: the table A the table B and the table AB which has 2 columns, one is the foreing key of the table A and one is the foreing key of the table B.
The entity framework shows only the tables A and B so how i can update only the content of the table AB?
I've tried to use the references in entity A and entity B but it gives me an exception saying that the entityset AB doesn't have the insert function and the delete function.

Answer 1

You try to make a
Public Virtual List<int> Ids
in your "A" and "B" Class to recover all the associations

Answer 2

For an insert, you would create a record for Table A, then add the Table B records to the item created that inserts into A. EF will handle the rest.
var tableA = new TableAtype { Description = "blah", etc.};
tableA.TableBtype.Add(new TableBtype { Property1 = "foo", Property2 = "bar"};
yourContext.AddToTableAtype(tableA);
yourContext.SaveChanges();

Answer 3

i'll be more specific using the code of my project as asked by TheGeekYouNeed
public void ModificaAbilitazioni(int IdGruppoAnagrafica, List<DefAbilitazioni> AbilitazioniList)
{
GruppiAnag gruppo = (from g in entities.GruppiAnags
where g.IdGruppoAnag == IdGruppoAnagrafica
select g).First();
List<DefAbilitazioni> tutteAbilitazioni = GetTutteAbilitazioni();
for (int i = 0; i < AbilitazioniList.Count; i++)
{
if (tutteAbilitazioni[i].GruppiAnags.Contains(gruppo))
{
tutteAbilitazioni[i].GruppiAnags.Remove(gruppo);
}
}
foreach (DefAbilitazioni abilitazione in AbilitazioniList)
{
for (int i = 0; i < tutteAbilitazioni.Count; i++)
{
if (tutteAbilitazioni[i].IdAbilitazione == abilitazione.IdAbilitazione)
{
tutteAbilitazioni[i].GruppiAnags.Add(gruppo);
}
}
}
entities.SaveChanges();
}
ok...here it is
this method should change the privilegies accounts.
First i recover the account using his id, than i recover all the privilegies and if in their reference they have the account recovered, then i remove it from the reference.
This way the account doesn't have any privilegies. Now in the privilegies that i've passed calling the method and in theri reference i put the account. (just a wipe and refill i'm just trying for now...)
i've also di the opposite, wiping the privilegies references in the account and refill them, but in both way won't work, in the first case it says that the third entity (AB) doesn't have the insert function

Answer 4

i've resolved the thing, the problem was that i was working with objects not attached to the db, i've tried with the attach like this
foreach (DefAbilitazioni abilitazione in abilitazioni)
{
entities.Attach(abilitazione);
gruppo.DefAbilitazionis.Add(abilitazione);
}
but it doesn't work it says that the entitykey is null, maybe if somebody gives me an example of using the attach i'll try to change my code that now is like this
public void ModificaAbilitazioni(int IdGruppoAnagrafica, List<DefAbilitazioni> AbilitazioniList)
{
GruppiAnag gruppo = (from g in entities.GruppiAnags
where g.IdGruppoAnag == IdGruppoAnagrafica
select g).First();
IEnumerable<int> idAbilitazioni = from id in AbilitazioniList
select id.IdAbilitazione;
List<DefAbilitazioni> abilitazioni = (from abilitazione in entities.DefAbilitazionis
where idAbilitazioni.Contains(abilitazione.IdAbilitazione)
select abilitazione).ToList();
gruppo.DefAbilitazionis.Clear();
foreach (DefAbilitazioni abilitazione in abilitazioni)
{
gruppo.DefAbilitazionis.Add(abilitazione);
}
entities.SaveChanges();
}