如何在 xamarin 表单中获得更多输入？

Question

我正在使用firebase RealTimeDataBase，我也想使用名称（GetUser（字符串电子邮件，字符串名称））来获取用户，那么我如何修改最后一个查询来做到这一点？ 因为当我注册时我成功地看到了名字，但是当我登录时我没有看到名字，但是电子邮件是的

用户由组成：电子邮件、姓名、类别、密码

代码：

FirebaseHelper.cs

namespace yourActivity.ViewModel
{

public class FirebaseHelper
{
    public static byte[] GetHash(string inputString)
    {
        using (HashAlgorithm algorithm = SHA256.Create())
        return algorithm.ComputeHash(Encoding.UTF8.GetBytes(inputString));
    }
    public static string GetHashString(string inputString)
    {
        StringBuilder sb = new StringBuilder();
        foreach (byte b in GetHash(inputString))
            sb.Append(b.ToString("X2"));
        return sb.ToString();
    }
    public static FirebaseClient firebase = new 
    FirebaseClient("https://youractivity-5acac.firebaseio.com/");

    //Read All    
    public static async Task<List<Users>> GetAllUser()
    {
        try
        {
            var userlist = (await firebase
            .Child("Users")
            .OnceAsync<Users>()).Select(item =>
            new Users
            {
                Email = item.Object.Email,
                Password = item.Object.Password,
                Nome = item.Object.Nome,
                Categoria = item.Object.Categoria
            }).ToList();
            return userlist;
        }
        catch (Exception e)
        {
            Debug.WriteLine($"Error:{e}");
            return null;
        }
    }

    //Read     
    public static async Task<Users> GetUser(string email)
    {
        try
        {
            var allUsers = await GetAllUser();
            await firebase
            .Child("Users")
            .OnceAsync<Users>();
            return allUsers.Where(a => a.Email == email).FirstOrDefault();
        }
        catch (Exception e)
        {
            Debug.WriteLine($"Error:{e}");
            return null;
        }
    }


    //Insert a user    
    public static async Task<bool> AddUser(string email, string password, string nome, string categoria)
    {
        try
        {
            await firebase
            .Child("Users")
            .PostAsync(new Users() { Email = email, Password = GetHashString(password), Nome = nome, Categoria = categoria});
            return true;
        }
        catch (Exception e)
        {
            Debug.WriteLine($"Error:{e}");
            return false;
        }
    }

    //Update     
    public static async Task<bool> UpdateUser(string email, string password, string nome, string categoria)
    {
        try
        {
            var toUpdateUser = (await firebase
            .Child("Users")
            .OnceAsync<Users>()).Where(a => a.Object.Email == email).FirstOrDefault();
            await firebase
            .Child("Users")
            .Child(toUpdateUser.Key)
            .PutAsync(new Users() { Email = email, Password = GetHashString(password) , Nome = nome, Categoria = categoria});
            return true;
        }
        catch (Exception e)
        {
            Debug.WriteLine($"Error:{e}");
            return false;
        }
    }

    //Delete User    
    public static async Task<bool> DeleteUser(string email)
    {
        try
        {
            var toDeletePerson = (await firebase
            .Child("Users")
            .OnceAsync<Users>()).Where(a => a.Object.Email == email).FirstOrDefault();
            await firebase.Child("Users").Child(toDeletePerson.Key).DeleteAsync();
            return true;
        }
        catch (Exception e)
        {
            Debug.WriteLine($"Error:{e}");
            return false;
        }
    }

}
}

SignupPage.xaml.cs

namespace yourActivity.View
{
[XamlCompilation(XamlCompilationOptions.Compile)]
public partial class SignupPage : ContentPage
{
    SignupViewModel signUpVM;
    public SignupPage()
    {
        InitializeComponent();
        signUpVM = new SignupViewModel();
        //set binding
        BindingContext = signUpVM;
    }
}
}

SignupViewModel.cs

namespace yourActivity.ViewModel

{
public class SignupViewModel : INotifyPropertyChanged
{
    private string email;
    public string Email
    {
        get { return email; }
        set
        {
            email = value;
            PropertyChanged(this, new PropertyChangedEventArgs("Email"));
        }
    }

    private string nome;
    public string Nome
    {
        get { return nome; }
        set
        {
            nome = value;
            PropertyChanged(this, new PropertyChangedEventArgs("Nome"));
        }
    }

    private string categoria;
    public string Categoria
    {
        get { return categoria; }
        set
        {
            categoria = value;
            PropertyChanged(this, new 
  PropertyChangedEventArgs("Categoria"));
        }
    }

    private string password;
    public event PropertyChangedEventHandler PropertyChanged;
    public string Password
    {
        get { return password; }
        set
        {
            password = value;
            PropertyChanged(this, new 
   PropertyChangedEventArgs("Password"));
        }
    }
    private string confirmpassword;
    public string ConfirmPassword
    {
        get { return confirmpassword; }
        set
        {
            confirmpassword = value;
            PropertyChanged(this, new 
  PropertyChangedEventArgs("ConfirmPassword"));
        }
    }
    public Command SignUpCommand
    {
        get
        {
            return new Command(() =>
            {
                if (Password == ConfirmPassword)
                    SignUp();
                else
                    App.Current.MainPage.DisplayAlert("", "Password must be same as above!", "OK");
            });
        }
    }
    private async void SignUp()
    {
        //null or empty field validation, check weather email and password is null or empty
        if (string.IsNullOrEmpty(Email) || string.IsNullOrEmpty(Password) || string.IsNullOrEmpty(Nome) || string.IsNullOrEmpty(Categoria))
            await App.Current.MainPage.DisplayAlert("Empty Values", "Please enter all the values", "OK");
        else
        {
            //call AddUser function which we define in Firebase helper class
            var user = await FirebaseHelper.AddUser(Email, Password, Nome, Categoria);
            //AddUser return true if data insert successfuly 
            if (user)
            {
                await App.Current.MainPage.DisplayAlert("SignUp Success", "", "Ok");
                //Navigate to Wellcom page after successfuly SignUp
                //pass user email to welcom page

                await App.Current.MainPage.Navigation.PushAsync(new TabbedPage1(email, nome));
            }
            else
                await App.Current.MainPage.DisplayAlert("Error", "SignUp Fail", "OK");
        }
    }
}
}

LoginPage.xaml.cs

namespace yourActivity.View
{
[XamlCompilation(XamlCompilationOptions.Compile)]
public partial class LoginPage : ContentPage
{
    LoginViewModel loginViewModel;
    public LoginPage()
    {
        loginViewModel = new LoginViewModel();
        InitializeComponent();
        BindingContext = loginViewModel;
    }

}
}

LoginViewModel.cs

namespace yourActivity.ViewModel
{
public class LoginViewModel : INotifyPropertyChanged
{
    public static byte[] GetHash(string inputString)
    {
        using (HashAlgorithm algorithm = SHA256.Create())
            return algorithm.ComputeHash(Encoding.UTF8.GetBytes(inputString));
    }
    public static string GetHashString(string inputString)
    {
        StringBuilder sb = new StringBuilder();
        foreach (byte b in GetHash(inputString))
            sb.Append(b.ToString("X2"));
        return sb.ToString();
    }


    private string email;
    public string Email
    {
        get { return email; }
        set
        {
            email = value;
            PropertyChanged(this, new PropertyChangedEventArgs("Email"));
        }
    }
    private string nome;
    public string Nome
    {
        get { return nome; }
        set
        {
            nome = value;
            PropertyChanged(this, new PropertyChangedEventArgs("Nome"));
        }
    }
    private string password;
    public event PropertyChangedEventHandler PropertyChanged;
    public string Password
    {
        get { return password; }
        set
        {
            password = value;
            PropertyChanged(this, new PropertyChangedEventArgs("Password"));
        }
    }
    public Command LoginCommand
    {
        get
        {
            return new Command(Login);
        }
    }
    public Command SignUp
    {
        get
        {
            return new Command(() => { App.Current.MainPage.Navigation.PushAsync(new SignupPage()); });
        }
    }
    private async void Login()
    {
        //null or empty field validation, check weather email and password is null or empty
        if (string.IsNullOrEmpty(Email) || string.IsNullOrEmpty(Password))
            await App.Current.MainPage.DisplayAlert("Empty Values", "Please enter Email and Password", "OK");
        else
        {
            //call GetUser function which we define in Firebase helper class
            var user = await FirebaseHelper.GetUser(Email);
            //firebase return null valuse if user data not found in database
            if (user != null)
                if (Email == user.Email && GetHashString(Password) == user.Password)
                {
                    await App.Current.MainPage.DisplayAlert("Login Success", "", "Ok");
                    //Navigate to Wellcom page after successfuly login
                    //pass user email to welcom page

                    await App.Current.MainPage.Navigation.PushAsync(new TabbedPage1(email, nome));
                }
                else
                    await App.Current.MainPage.DisplayAlert("Login Fail", "Please enter correct Email and Password", "OK");
            else
                await App.Current.MainPage.DisplayAlert("Login Fail", "User not found", "OK");
        }
    }
}
}

TabbedPage1.xaml.cs

namespace yourActivity
{
[XamlCompilation(XamlCompilationOptions.Compile)]
public partial class TabbedPage1 : TabbedPage
{
    TabbedPage1ViewModel TabbedPageVM;
    readonly FirebaseHelper firebaseHelper = new FirebaseHelper();
    public TabbedPage1(string email, string nome)
    {
        InitializeComponent();
        TabbedPageVM = new TabbedPage1ViewModel(email, nome);
        BindingContext = TabbedPageVM;


    }

}
}

TabbedPage1ViewModel

namespace yourActivity.ViewModel
{
public class TabbedPage1ViewModel : INotifyPropertyChanged
{
    public TabbedPage1ViewModel(string email2, string nome2)
    {
        Email = email2;
        Nome = nome2;
    }

    private string email;

    public string Email
    {
        get { return email; }
        set { email = value; }
    }

    private string nome;

    public string Nome
    {
        get { return nome; }
        set { nome = value; }

    }

    private string categoria;

    public string Categoria
    {
        get { return categoria; }
        set { categoria = value; }
    }

    private string password;
    public event PropertyChangedEventHandler PropertyChanged;
    public string Password
    {
        get { return password; }
        set
        {
            password = value;
            PropertyChanged(this, new PropertyChangedEventArgs("Password"));
        }
    }
    public Command UpdateCommand
    {
        get { return new Command(Update); }
    }
    public Command DeleteCommand
    {
        get { return new Command(Delete); }
    }
    //For Logout
    public Command LogoutCommand
    {
        get
        {
            return new Command(() =>
            {
                App.Current.MainPage.Navigation.PushAsync(new LoginPage());
            });
        }
    }



    //Update user data
    private async void Update()
    {
        try
        {
            if (!string.IsNullOrEmpty(Password))
            {
                var isupdate = await FirebaseHelper.UpdateUser(Email, Password, Nome, Categoria);
                if (isupdate)
                    await App.Current.MainPage.DisplayAlert("Update Success", "", "Ok");
                else
                    await App.Current.MainPage.DisplayAlert("Error", "Record not update", "Ok");
            }
            else
                await App.Current.MainPage.DisplayAlert("Password Require", "Please Enter your password", "Ok");
        }
        catch (Exception e)
        {
            Debug.WriteLine($"Error:{e}");
        }
    }

    //Delete user data
    private async void Delete()
    {
        try
        {
            var isdelete = await FirebaseHelper.DeleteUser(Email);
            if (isdelete)
                await App.Current.MainPage.Navigation.PopAsync();
            else
                await App.Current.MainPage.DisplayAlert("Error", "Record not delete", "Ok");
        }
        catch (Exception e)
        {
            Debug.WriteLine($"Error:{e}");
        }
    }
}
}

Answer 1

您可以使用 if 语句来决定使用email 或name 来查询用户：

//Read     
public static async Task<Users> GetUser(string email = null, string name = null)
{
    try
    {
        var allUsers = await GetAllUser();
        await firebase
        .Child("Users")
        .OnceAsync<Users>();

        if (email != null && email.Length> 0)
        {
            return allUsers.Where(a => a.Email == email).FirstOrDefault();
        }

        return allUsers.Where(a => a.Name == name).FirstOrDefault();
    }
    catch (Exception e)
    {
        Debug.WriteLine($"Error:{e}");
        return null;
    }
}