select the last record of a table with entity framework

Question

hello I am saving a record in the sale table and then by means of the user id I am trying to access the last record that I save to get the id and use that value to save in another table

but i get this error:

System.InvalidOperationException: 'The LINQ expression 'DbSet<sale>
    .Where(v => v.userId == __idU_0)
    .LastOrDefault()' could not be translated. Either rewrite the query in a form that can be translated, or switch to client evaluation explicitly by inserting a call to either AsEnumerable(), AsAsyncEnumerable(), ToList(), or ToListAsync(). See https://go.microsoft.com/fwlink/?linkid=2101038 for more information.'

What is the correct way to make the query to access the last record?

private void button2_Click(object sender, EventArgs e)
        {

            using (var context = new AppDbContext())
            {
                sale S = new sale();
                V.date = DateTime.Today.Date;
                V.userId = dataU.idU;

                context.Add(V);
               var save = context.SaveChanges();
                if( save > 0)
                {
                  var idsale= context.sale.LastOrDefault(x => x.userId == dataU.idU)?.saleId;


                    MessageBox.Show(""+ idsale);
                }

                }

Same question: https://stackoverflow.com/a/5212787/12661958 – Thibaut Jun 08 '20 at 14:20 — Thibaut, Jun 08 '20 at 14:20
switch the sort order and select the first instead? – Wiebe Tijsma Jun 08 '20 at 14:27 — Wiebe Tijsma, Jun 08 '20 at 14:27

score 2 · Answer 1 · answered Jun 08 '20 at 14:27

Entity Framework updates the saleId of S, the object that you inserted, automatically. You don't have to retrieve it. Your code should be like this

 context.Add(V);

 context.SaveChanges();

 MessageBox.Show(""+ s.saleId);

The context.SaveChanges() returns the number of rows being affected according to the official documentation. So, you can keep the check of the value returned, that would not hurt.

 context.Add(V);

 var save = context.SaveChanges();

 if ( save > 0)
   {
       MessageBox.Show(""+ s.saleId);
   }

Check this link to see how it works https://www.entityframeworktutorial.net/faq/how-to-get-id-of-saved-entity-in-entity-framework.aspx

select the last record of a table with entity framework

1 Answers1