将下拉选择器连接到数据库

Question

我正在做一个项目，我必须创建一个注册页面，并且在该页面中我必须有一个下拉选择器，以便用户可以选择他们来自的国家/地区。我正在按照我在 youtube 上找到的这个视频中的一些步骤进行操作：https://www.youtube.com/watch?v=E_0XDyy4ef8 和关于 udemy 的课程，但他们没有介绍如何创建后端代码以将其连接到数据库的步骤。如果有人可以帮助我，那就太好了！

xaml-

<Picker ItemDisplayBinding="{Binding CountryName}" 
                        x:Name="EntCountry" 
                        Title="Select Country" 
                        ItemsSource="{Binding CountList}" 
                        TextColor="White" 
                        TitleColor="White"/>

cs-

 private async void BtnSignUp_OnClicked(object sender, EventArgs e)
        {
            var response = await ApiService.RegisterUser(EntName.Text, EntEmail.Text, EntPassword.Text, EntConfirmPassword.Text, EntDOB.Text, EntCountry);
                if (response)
            {
                await DisplayAlert("Hello!", "Your account has been created", "Okay");
                await Navigation.PushModalAsync(new LoginPage()); //This will transition to another screen. 
            }
            else
            {
                await DisplayAlert("Hello!", "There is something wrong", "Okay");
            }
        }

Register.cs

class Register
    {
        public string Name { get; set; }
        public string Email { get; set; }
        public string Password { get; set; }
        public string ConfirmPassword { get; set; }
        public string Country { get; set; }
        public string DOB { get; set; }
    }

ApiService.cs-

public static async Task<bool> RegisterUser(string name, string email, string password, string confirmpassword, string dob, string country)
        {
            var register = new Register()
            {
                Name = name,
                Email = email,
                Password = password,
                ConfirmPassword = confirmpassword,
                Country = country,
                DOB = dob,

Country.cs-

public class Country
    {
        public int CountryId { get; set; }
        public string CountryName { get; set; }
    }

CountryViewModel.cs-

class CountryViewModel
    {
        public IList<Country> CountList { get; set; }

        public CountryViewModel()
        {
            try
            {
                CountList = new ObservableCollection<Country>();
                CountList.Add(new Country { CountryId = 1, CountryName = "United States" });
                CountList.Add(new Country { CountryId = 2, CountryName = "Ecuador" });
                CountList.Add(new Country { CountryId = 3, CountryName = "Brazil" });
                CountList.Add(new Country { CountryId = 4, CountryName = "Argentina" });
                CountList.Add(new Country { CountryId = 5, CountryName = "Colombia" });
                CountList.Add(new Country { CountryId = 6, CountryName = "Peru" });
                CountList.Add(new Country { CountryId = 7, CountryName = "Chile" });
                CountList.Add(new Country { CountryId = 8, CountryName = "Venezuela" });
                CountList.Add(new Country { CountryId = 9, CountryName = "Bolivia" });
                CountList.Add(new Country { CountryId = 10, CountryName = "Uruguay" });
                CountList.Add(new Country { CountryId = 11, CountryName = "Paraguay" });
                CountList.Add(new Country { CountryId = 12, CountryName = "Mexico" });
            }
            catch(Exception)
            {

            }
        }
    }

Answer 1

您是否为 VM 使用了 BindingContext？看看this。作为建议，如果您使用 VM，请尝试将单击按钮的代码放入其中。