I'm trying to update two entities at the same time but the change is not applying and I think that when I try to return the update entity it doesn't even found it.

Here is my Razor view:

 public IActionResult OnPost()
 {
        if (!ModelState.IsValid)
        {
            return Page();
        }
        
        repositorioFamiliar.Actualizar(Familiar);

        return RedirectToPage("/Familiares/DetalleFamiliar", new { IdPaciente = Familiar.IdPaciente });
}

Here is my update function:

public FamiliaresPer Actualizar(FamiliaresPer familiar)
{
        var familiarActualizar = (from f in _context.Familiars.Where(p => p.IdFamiliar == familiar.IdFamiliar) select f).FirstOrDefault();

        if (familiarActualizar != null)
        {
            familiarActualizar.Correo = familiar.Correo;
            _context.Update(familiarActualizar);
            _context.SaveChanges();
        }

        var personaActualizar = (from p in _context.Personas.Where(p => p.Id == familiar.IdPersona) select p).FirstOrDefault();

        if (personaActualizar != null)
        {
            personaActualizar.Telefono = familiar.Telefono;
            _context.Update(personaActualizar);
            _context.SaveChanges();
        }

        var familiares = from p in _context.Familiars
                         from p1 in _context.Personas
                         where p.IdPaciente == familiar.IdPaciente
                         where p.IdPersona == p1.IdPersona
                         select new FamiliaresPer()
                                    {
                                        IdFamiliar = p.IdFamiliar,
                                        IdPaciente = p.IdPaciente,
                                        IdPersona = p1.IdPersona,
                                        Id = p1.Id,
                                        Nombres = p1.Nombres,
                                        Apellidos = p1.Apellidos,
                                        Genero = p1.Genero,
                                        Telefono = p1.Telefono,
                                        Parentesco = p.Parentesco,
                                        Correo = p.Correo,
                                    };

        FamiliaresPer familiaresPer = familiares.FirstOrDefault();
        return familiaresPer; 
}

When I submit the form I get an error

NullReferenceException: Object reference not set to an instance of an object

And the link shows the IdPaciente = 0 when it should use the same IdPaciente of the updated entity (which the Id never changes).

CodePudding user response：

In your OnPost( ) Action Method, you used repositorioFamiliar.Actualizar(Familiar); but it looks like you didn't define 'Familiar'.

In addition, when I look at your code. I can give you an advice. Let's say your first update was done correctly and you got an error in the second update case. But you want both to be updated at the same time. Assume that the first object is updated in the database but the second one isn't. This is a problem, right? Unit of Work design pattern is very useful to solve this. In brief, The approach should be to do SaveChanges() after both update processes are completed so there will be no changes in the database until both updates are completed.