entity framework: retrieve Id of new entry upon creation

Question

is there a way to get the id of the last entry created without asking for it specifically?

I am doing this:

 public async Task SaveItemAsync(tblUsers item) //change here
        {
            if (item == null) throw new ArgumentException(nameof(item));
            await InitializeAsync();
            if (item.Id == null)
            {
                try
                {
                    await _table.InsertItemAsync(item);
                }
                catch (Exception e)
                {
                    var message = e.Message;
                }
            }
            else await _table.ReplaceItemAsync(item);
        }

anod nothing is returned but an entry with a Id is created on the db.

How can I alter that so that the Id of the new entry is returned?

Does this answer your question? [How can I retrieve Id of inserted entity using Entity framework?](https://stackoverflow.com/questions/5212751/how-can-i-retrieve-id-of-inserted-entity-using-entity-framework) — Guru Stron, May 17 '23 at 13:51
You didn't post any Entity Framework code. There's no `InsertItem` or `ReplaceItem` in EF, nor is it needed. When you call `SaveChanges` **all** changes are detected and stored. Any generated IDs are automatically retrieved. BTW all means *all* - if there are any pending delete when your `InsertItem` calls `SaveChanges`, you'll end up with DELETEd items — Panagiotis Kanavos, May 17 '23 at 14:00
BTW there's no need for `SaveItemAsync` either - just call `context.Update(item)`. If `item`'s PK has a value, EF will generate an UPDATE. If not, it will generate an INSERT. This very well documented — Panagiotis Kanavos, May 17 '23 at 14:03

Guru Stron · Accepted Answer · 2023-05-17T14:06:59.537

1

If id is database generated Entity Framework should fill it in the inserted entity, i.e.:

_ctx.Items.Add(item);
await _ctx.SaveChangesAsync();
var insertedId = item.Id;

P.S.

Possibly you might want to use something like item.Id == default to check if the id is empty.
Consider using DbContext.Update or DbSet.Update method which will perform key checking for you (see the Remarks section).

edited May 17 '23 at 14:06

answered May 17 '23 at 13:50

Guru Stron

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You should stress that `SaveChanges` saves all changes, including DELETEs, otherwise the OP's next question may be "Why does my Insert delete 42 records?" – Panagiotis Kanavos May 17 '23 at 14:01
1

PS: Also that `Update` will Insert or Update based on the values of the entity's PK properties, there's no need to check whether to Add or Update – Panagiotis Kanavos May 17 '23 at 14:04

entity framework: retrieve Id of new entry upon creation

1 Answers1