public UsersPage()
        {
            var vm = new UsersViewModel();

            this.BindingContext            = vm;
            vm.DisplaySaveSucessPrompt    += () => DisplayAlert("Success", "New User has been registered successfully", "OK");
            vm.DisplayUserExistPrompt     += () => DisplayAlert("Error", "The username has already been registered", "OK");
            vm.DisplaySaveFailedPrompt    += () => DisplayAlert("Error", "User registration failed, Please try again", "OK");
            vm.DisplayRequriedFieldPrompt += () => DisplayAlert("Error", "User, Password, Firstname and Lastname Fields are required", "OK");
            InitializeComponent();

            Username.Completed += (object sender, EventArgs e) =>
            {
                Password.Focus();
            };

            Password.Completed += (object sender, EventArgs e) =>
            {
                Firstname.Focus();
            };

            Firstname.Completed += (object sender, EventArgs e) =>
            {
                Lastname.Focus();
            };

            Lastname.Completed += (object sender, EventArgs e) =>
            {
                Phonenumber.Focus();
            };
            Phonenumber.Completed += (object sender, EventArgs e) =>
            {
                vm.SubmitCommand.Execute(null);
            };
        }
        public PatientsPage()
        {
            //var vm = new PatientsViewModel();
            //this.BindingContext = vm;
            InitializeComponent();
            BindingContext = _viewModel = new PatientsViewModel();
            _viewModel.DisplayClientAlreadyRegisteredPrompt += () => DisplayAlert("Error", "The Patient is Aready Registered", "OK");
            _viewModel.DisplayRegistrationSuccessPrompt     += () => DisplayAlert("Success", "The Patient has been registered successfully", "OK");
            _viewModel.DisplayRegistrationFailedPrompt      += () => DisplayAlert("Error", "User registration failed, Please try again", "OK");
            _viewModel.DisplayRequiredFieldPrompt           += () => DisplayAlert("Error", "OPD Number, First Name, Last Name and Village Fields are required", "OK");
            _viewModel.activity = activity;

            Opdnumber.Completed += (object sender, EventArgs e) =>
            {
                Firstname.Focus();
            };

            Firstname.Completed += (object sender, EventArgs e) =>
            {
                Lastname.Focus();
            };
            Housenumber.Completed += (object sender, EventArgs e) =>
            {
                Village.Focus();
            };
            Village.Completed += (object sender, EventArgs e) =>
            {
                Phonenumber.Focus();
            };
            Phonenumber.Completed += (object sender, EventArgs e) =>
            {
                _viewModel.SubmitCommand.Execute(null);
            };
        }