Object is not persisted when using Entity Framework

Question

I’m using the Entity Framework 6 and the Sqlserver. I have an object called category, where I want to persist it in the bank. and when I run this function, it persists the object correctly because I have a datagrid where I can observe that it worked. But when I close the application and search again the object is no longer there.

• Why does this happen?
• It is saved only at runtime and not persists?

• I also noticed that the method Savechanges returns an integer, has something to indicate whether the insertion was right or wrong? for example, if returns 1 worked, if it is 0 wrong.

  private void btnSalvar_Click(object sender, RoutedEventArgs e)
  {
      categoria objCategoria = new categoria();
  objCategoria.Id = 0;
  objCategoria.descricao = ttbDescricao.Text;
  objCategoria.observacao = ttbObservacao.Text;
  objCategoria.status = 1;
  
  using (SiscabEntities SisEF = new SiscabEntities())
  {
      //SisEF.categoria.Add(objCategoria);
      if (ttbCodigo.Text.Equals(""))
      {
          SisEF.Entry(objCategoria).State = EntityState.Added;
      }
      else
      {
          SisEF.Entry(objCategoria).State = EntityState.Modified;
      }
      SisEF.SaveChanges();
      Inicializa();
          }
        }
  

Answer 1

The local project database is in the same project folder, always when I run the project it plays the database to bin/debug creating a new database. what should be done to solve the problem is to go to the properties of the bank file. mdf and change the 'Change to output directories' field and put the 'Copy if newer' option'

Answer 2

good afternoon. By the code posted, the objCategory object is missing from the category table. To include:

SisEF.categoria.Add(objCategoria);

When it is changed, you have to locate the record in the table and then make the updates.

categoria catAlterada = new categoria();
catAlterada = SisEF.categoria.find(objCategoria.id);
catAlterada = objcategoria;
SisEf.SaveChanges();

Answer 3

The way you are trying to do it is in a disconnected senario, that is, your context has no knowledge of your object that you are trying to persist, so you need to teach the walk of the stones to it. The first point you need to change is in your EntityState.Added; this works, but you need to use Attach with its object, the simplest thing to do is to use the add.

Another point you need to change is in editing, you make instance of a category, but do not set the ID value on it when this is editing will give error.

See how you can be doing in this senario.

private void btnSalvar_Click(object sender, RoutedEventArgs e)
{
    using (SiscabEntities SisEF = new SiscabEntities())
    {
        categoria objCategoria = new categoria();
        objCategoria.descricao = ttbDescricao.Text;
        objCategoria.observacao = ttbObservacao.Text;
        objCategoria.status = 1;

        if (ttbCodigo.Text.Equals(""))
        {
            // veja o nome correto  da categoria no seu contexto
            SisEF.Categorias.Add(objCategoria);
        }
        else
        {
            objCategoria.Id = (int)ttbCodigo.Text;
            SisEF.Attach(objCategoria);         
            SisEF.Entry(objCategoria).State = EntityState.Modified;
        }
        SisEF.SaveChanges();
        Inicializa();
    }
}

Another password would be the connected one, in which you would have your object in the context, that is, your object has all the property of the EF and it knows the current state of your object.

private void btnSalvar_Click(object sender, RoutedEventArgs e)
{
    using (SiscabEntities SisEF = new SiscabEntities())
    {
        if (!ttbCodigo.Text.Equals(""))
        {           
            var categoria = SisEF.Categorias.Find(1ttbCodigo.Text); // todo convert to int ...
            categoria.descricao = ttbDescricao.Text;
            categoria.observacao = ttbObservacao.Text;
            categoria.status = 1;   
        }   
        else
        {
            categoria objCategoria = new categoria();
            objCategoria.descricao = ttbDescricao.Text;
            objCategoria.observacao = ttbObservacao.Text;
            objCategoria.status = 1;
            SisEF.Categorias.Add(objCategoria);
        }

        SisEF.SaveChanges();
        Inicializa();
    }
}