Uploading new row to database table Entity Framework

Question

LAST EDIT:

There were various problems with my code, which are explained in the comments of two answers. In the end i've used the following code:

using (var context = new CijferDBEntities()) 
        { 
            context.Student.Add(newStudent);
            try
            {
                context.SaveChanges();
            }
            catch (DbEntityValidationException ex)
            {
                foreach (var entityValidationErrors in ex.EntityValidationErrors)
                {
                    foreach (var validationError in entityValidationErrors.ValidationErrors)
                    {
                        Console.Write("Property: " + validationError.PropertyName + " Error: " + validationError.ErrorMessage);
                    }
                }
            }

        }

EDIT: I've explained this badly, I'd like to know how I would insert a new student (which I created here) into the table dbo.Student.

---

I'd like to insert a new row into my table in the database using C#.

First have I defined a student here:

private void btnToevoegen_Click(object sender, EventArgs e)
{
        EntityVoorbeeld vb = new EntityVoorbeeld();

        string Roepnaam = txtRoepnaam.Text;
        string Voegsel = txtVoegsel.Text;
        string Achternaam = txtAchternaam.Text;
        DateTime Geboortedatum = Convert.ToDateTime(txtGeboortedatum.Text);
        string Adres = txtAdres.Text;
        string Postcode = txtPostcode.Text;
        string Woonplaats = txtWoonplaats.Text;
        string Email = txtEmail.Text;
        string Telefoon = txtTelefoon.Text;
        string Mobiel = txtMobiel.Text;

        // Create new student
        Student newStudent = new Student();
        newStudent.Roepnaam = Roepnaam;
        newStudent.voegsel = Voegsel;
        newStudent.Achternaam = Achternaam;
        newStudent.Geboortedatum = Geboortedatum;
        newStudent.Adres = Adres;
        newStudent.Postcode = Postcode;
        newStudent.Woonplaats = Woonplaats;
        newStudent.Email = Email;
        newStudent.Telefoon = Telefoon;
        newStudent.Mobiel = Mobiel;

        // Add student to table
        vb.Studenten.add(newStudent);

        vb.SaveChanges();
}

which I want to be inserted into the table once the button is clicked.

I have used the following code to fetch the students from the database:

public ObservableCollection<Student> Studenten(string klas, string schooljaar)
{
        Lesgroep groep = ce.Lesgroep.SingleOrDefault(g => g.Naam == klas && g.Schooljaar == schooljaar);
        return new ObservableCollection<Student>(groep.Student.OrderBy(s => s.Achternaam).ThenBy(s => s.Roepnaam));
}

At this code:

vb.Studenten.add(newStudent);

i get the following error upon hovering over Studenten

'CijferDB.EntityVoorbeeld.Studenten(string, string)' is a 'method', which is not valid in the given context.

Turned out my DBSet was missing, i edited in the following:

public DbSet<Student> Students { get; set; }

Answer 1

Perhaps there is a violation of constraint , ensure that there is not violation of primary key

Answer 2

To summarize:

1. It turns out that OP encounter DbEntityValidationException which is cause by one of the model field being null when inserting to database.

2. The DBSet Student that OP include in previous code is also causing the newStudent instance to not insert into database as he was not referring to his DbContext class, rather EntityVoorbeeld, a normal class which does not contain the DbSet Student.

Answer 3

Studenten is a method (which you are showing on your question). For adding a new entity you need to add it to your context's DbSet, not to a method that returns an ObservableCollection.

Your DbContext (by your code, the type EntityVoorbeeld) will have a DbSet property of type Student (with a name, that you are not providing). Use that name to add it:

vb.TheNameOfTheStudentDbSet.Add(newStudent);
vb.SaveChanges();

In English, that'd more likely be called Students, so your EntityVoorbeeld class would look something like:

public class EntityVoorbeeld : DbContext
{
   public DbSet<Student> Students { get; set; }     

   /* 
      ... the rest of your context's properties and methods ...
   */
}

But your names may vary.