Insert data to Firebase and set restriction to UI(username and password) in xamarin form-CodePudding

I have create acc page in xamarin form. The fields are basic info for customer like firstname, lastname and I have field "username" and "password". So it goes like this. I want to set a rule for;

Username; -no duplication for username. Because every username inputted by customer, It check in database if that username is avail or not. Example, username: dummy123

I want this way for username; -upon tapping the entry field for username, and assume customer will input "dummy123" a toast will appear like "username already exist"

Password; -password must contain; capital letter, small char, special char, number and 8 letter and above.

I want this way for password; -upon tapping the entry field for password, and assume customer will input "@imcool123" a toast will appear like this; "password must contain capital letter, small char, special char, number and 8 letter and above"

any link posted will be appreciated. Thank you so much.

CodePudding user response：

You can follow the steps below to make your ideas work.

First, you can create a model for deserializing your response.

 public class Person  
    {  
        public string Name { get; set; }  
    }

Second, you can write the code to connect the Firebase Realtime Database.

using Firebase.Database;  
using Firebase.Database.Query;  
  
FirebaseClient firebase = new FirebaseClient("https://");

Third, create an Entry with TextChanged in the MainPage.xaml.

 <StackLayout>
        <Entry x:Name="EntryText" TextChanged="EntryText_TextChanged" />
 </StackLayout>

Fourth, fulfill the EntryText_TextChanged method in MainPage.xaml.cs. The method provide a way to match the data which in the Firebase.

 public partial class MainPage : ContentPage
    {
        public MainPage()
        {
            InitializeComponent();
        }

        private void EntryText_TextChanged(object sender, TextChangedEventArgs e)
        {
            var oldText = e.OldTextValue;
            var newText = e.NewTextValue;

            var person = await firebaseHelper.GetPerson(Convert.ToString(EntryText.Text);
            if (person != null)
            {
                
                EntryText.Text = person.Name;
                // this is a Toast method
                await DependencyService.Get<IToast>().ShortAlert("username already exist");

            }
            else
            {
                
            }
        }
// This is the method to find the name if it has existed
        public async Task<Person> GetPerson(string personName)
        {
            var allPersons = await GetAllPersons();
            await firebase
              .Child("Persons")
              .OnceAsync<Person>();
            return allPersons.Where(a => a.PersonName == personName).FirstOrDefault();
        }
    }

In addition, here is the information about the Xamarin.Forms - How To Make Toast Message Using Dependency Service. You can check this article.