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https://github.com/egbakou/formvalidation
Real time form validation using Triggers and Converters in Xamarin.Forms
https://github.com/egbakou/formvalidation
converters forms triggers validation xamarin-forms
Last synced: about 1 month ago
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Real time form validation using Triggers and Converters in Xamarin.Forms
- Host: GitHub
- URL: https://github.com/egbakou/formvalidation
- Owner: egbakou
- Created: 2019-03-23T12:37:42.000Z (almost 6 years ago)
- Default Branch: master
- Last Pushed: 2019-03-25T10:15:46.000Z (almost 6 years ago)
- Last Synced: 2024-10-30T00:38:24.233Z (3 months ago)
- Topics: converters, forms, triggers, validation, xamarin-forms
- Language: C#
- Homepage: https://lioncoding.com/2019/03/23/2019-03-23-utiliser-des-triggers-et-converters-pour-valider-un-formulaire-dans-xamarin-forms/
- Size: 2.74 MB
- Stars: 3
- Watchers: 1
- Forks: 1
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
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README
## Real time form validation using Triggers and Converters in Xamarin.Forms
In this Xamarin.Forms project, we want to use **Triggers** and **Converters** to validate in real time login form.
## Demo on Youtube
[](https://www.youtube.com/watch?v=L6PELicCyMk)
## Create project and select Blank model
## Project structure at the end
## Topic
The goal is to check if email(user name) and password are correct before enable login button.
- The email must match the following regular expression `^[a-z0-9._-]+@[a-z0-9._-]+\\.[a-z]{2,6}$`
- The password must have 8 characters at least.
- If email or password is invalid, login button will be disabled and error labels visible.
## Our converters
- Code for Converter that validate email address and used by trigger to enable login button:
```csharp
using System;
using System.Globalization;
using System.Text.RegularExpressions;
using Xamarin.Forms;
namespace FormValidation.Converters
{
///
/// Converter that check if username is correct and return true, otherwise return false.
///
public class UsernameCorrectConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
return isUserNameCorrect(value);
}
public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
{
throw new NotImplementedException();
}
private bool isUserNameCorrect(object value)
{
if (value is string)
{
bool isEmail = Regex.IsMatch(
(string)value, "^[a-z0-9._-]+@[a-z0-9._-]+\\.[a-z]{2,6}$");
int length = ((string)value).Trim().Length;
if (length >= 7 && length <= 60 && isEmail)
return true;
else
return false;
}
return false;
}
}
}
```
- Code for Converter that validate email address and used by trigger to show email error label:
```csharp
using System;
using System.Globalization;
using System.Text.RegularExpressions;
using Xamarin.Forms;
namespace FormValidation.Converters
{
///
/// Converter that check if username is correct and return true, otherwise return false.
/// The idea is to be able to show or hide username error label.
///
public class UsernameCorrectToHideLabelConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
return isUserNameCorrect(value);
}
public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
{
throw new NotImplementedException();
}
private bool isUserNameCorrect(object value)
{
if (value == null || ((string)value).Length == 0)
return true;
if (value is string)
{
bool isEmail = Regex.IsMatch(
(string)value, "^[a-z0-9._-]+@[a-z0-9._-]+\\.[a-z]{2,6}$");
int length = ((string)value).Trim().Length;
if (length >= 7 && length <= 60 && isEmail)
return true;
else
return false;
}
return false;
}
}
}
```
- Code for Converter that validate password and used by trigger to enable login button:
```csharp
using System;
using System.Globalization;
using Xamarin.Forms;
namespace FormValidation.Converters
{
///
/// Converter that check if passsword is correct and return true, otherwise return false.
///
public class PasswordCorrectConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
return isPasswordCorrect(value);
}
public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
{
throw new NotImplementedException();
}
private bool isPasswordCorrect(object value)
{
if (value is string)
{
int length = ((string)value).Trim().Length;
if (length >= 8)
return true;
else
return false;
}
return false;
}
}
}
```
- Code for Converter that validate password and used by trigger to show password error label:
```csharp
using System;
using System.Globalization;
using Xamarin.Forms;
namespace FormValidation.Converters
{
///
/// Converter that check if password is correct and return true, otherwise return false.
/// The idea is to be able to show or hide password error label.
///
class PasswordCorrectToHideLabelConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
return isPasswordCorrect(value);
}
public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
{
throw new NotImplementedException();
}
private bool isPasswordCorrect(object value)
{
if (value == null || ((string)value).Length == 0)
return true;
if (value is string)
{
int length = ((string)value).Trim().Length;
if (length >= 8)
return true;
else
return false;
}
return false;
}
}
}
```
## Login page
```xaml
```
## Code behind
```csharp
using Xamarin.Forms;
namespace FormValidation
{
public partial class FormsPage : ContentPage
{
public FormsPage()
{
InitializeComponent();
ShowLoginIndicator.IsRunning = false;
}
private void LoginBt_Clicked(object sender, System.EventArgs e)
{
ShowLoginIndicator.IsVisible = true;
ShowLoginIndicator.IsRunning = true;
}
private void UserNameEntry_Focused(object sender, FocusEventArgs e)
{
UserNameEntry.HorizontalTextAlignment = TextAlignment.Center;
}
private void UserNameEntry_Unfocused(object sender, FocusEventArgs e)
{
UserNameEntry.HorizontalTextAlignment = TextAlignment.Start;
}
private void PasswordEntry_Focused(object sender, FocusEventArgs e)
{
PasswordEntry.HorizontalTextAlignment = TextAlignment.Center;
}
private void PasswordEntry_Unfocused(object sender, FocusEventArgs e)
{
PasswordEntry.HorizontalTextAlignment = TextAlignment.Start;
}
}
}
```