public ActionResult Edit(MedicalCertificateViewModel[] medicalCertificates)
        {
            var formModel = medicalCertificates.Single();

            ModelMedicalCertificate certificateModel = null;

            // validates the existence and the compliance of the certificate model
            if (formModel.ModelId.HasValue)
            {
                certificateModel = this.db.ModelMedicalCertificates.FirstOrDefault(mmc => mmc.Id == formModel.ModelId);
                if (certificateModel == null)
                    this.ModelState.AddModelError<MedicalCertificateViewModel>(m => m.ModelId, "O modelo de atestado informado não é válido");
                else
                {
                    // for each field in the model, all must exist in the formModel
                    if (certificateModel.Fields.Any(field => formModel.Fields.All(f => f.Name.ToLower() != field.Name.ToLower())))
                        this.ModelState.AddModelError<MedicalCertificateViewModel>(m => m.Fields, "Dados inválidos. As informações recebidas não condizem com o modelo de atestado especificado");

                    // #KNOWN ISSUE# The next statements shouldn't exist. The REQUIRED attribute should work :(
                    // for all fields existing in the formModel, all must have a value
                    for (var i = 0; i < formModel.Fields.Count; i++)
                    {
                        var field = formModel.Fields[i];
                        if (string.IsNullOrEmpty(field.Value))
                            this.ModelState.AddModelError("Fields[" + i + "]", "O valor do campo é requerido");
                    }
                }
            }

            if (!formModel.ModelId.HasValue && !formModel.Id.HasValue)
                this.ModelState.AddModelError<MedicalCertificateViewModel>(m => m.ModelId, "É necessário informar o modelo do atestado");

            // validates the existence of the patient
            if (formModel.PatientId.HasValue && !this.db.Patients.Any(m => m.Id == formModel.PatientId))
                this.ModelState.AddModelError<MedicalCertificateViewModel>(m => m.ModelId, "O paciente informado não é válido");

            if (this.ModelState.IsValid)
            {
                MedicalCertificate certificate = null;
                if (formModel.Id == null)
                {
                    certificate = new MedicalCertificate()
                    {
                        CreatedOn = this.GetUtcNow(),
                        PatientId = formModel.PatientId.Value,
                        PracticeId = this.DbUser.PracticeId,
                    };
                    this.db.MedicalCertificates.AddObject(certificate);
                }
                else
                {
                    certificate = this.db.MedicalCertificates.FirstOrDefault(r => r.Id == formModel.Id);
                    if (certificate == null)
                        return this.ObjectNotFound();
                }

                if (certificateModel != null)
                {
                    certificate.ModelMedicalCertificateId = certificateModel.Id;
                    certificate.Text = certificateModel.Text;
                }
                else
                    certificate.ModelMedicalCertificateId = null;

                certificate.Patient.IsBackedUp = false;
                certificate.Fields.Update(
                        formModel.Fields,
                        (vm, m) => vm.Name == m.Name,
                        (vm, m) =>
                        {
                            m.Name = vm.Name;
                            m.Value = vm.Value;
                            m.PracticeId = this.DbUser.PracticeId;
                        },
                        (m) => this.db.MedicalCertificateFields.DeleteObject(m));

                certificate.IssuanceDate = this.ConvertToUtcDateTime(formModel.IssuanceDate.Value);
                this.db.SaveChanges();

                // todo: use GetViewModel method:
                //var viewModel = GetViewModel(certificate);

                var viewModel = new MedicalCertificateViewModel
                {
                    Id = certificate.Id,
                    ModelId = certificate.ModelMedicalCertificateId,
                    // the only situation in which ModelName will be null is when the model certificate has been removed
                    ModelName = certificate.ModelMedicalCertificate != null ? certificate.ModelMedicalCertificate.Name : null,
                    PatientId = certificate.PatientId,
                    IssuanceDate = this.ConvertToLocalDateTime(certificate.IssuanceDate),
                    Fields = (from f in certificate.Fields
                              select new MedicalCertificateFieldViewModel()
                              {
                                  Id = f.Id,
                                  Name = f.Name,
                                  Value = f.Value,
                              }).ToList(),
                };

                return this.View("Details", viewModel);
            }

            formModel.ModelOptions = this.db.ModelMedicalCertificates.ToList().Select(mmc => new SelectListItem() { Text = mmc.Name, Value = mmc.Id.ToString() }).ToList();
            return this.View("Edit", formModel);
        }