New pages, LoginViewModel, Validation (in progress)

12 files changed, 245 insertions, 100 deletions

diff --git a/Juick/App.xaml.cs b/Juick/App.xaml.cs
index 98dc31c..03e0d10 100644
--- a/Juick/App.xaml.cs
+++ b/Juick/App.xaml.cs
@@ -10,22 +10,31 @@ namespace Juick
 {

     public partial class App : Application

     {

-        public void NavigateTo(Uri param) {

-            RootFrame.Navigate(param);

+        public void NavigateTo(Uri param, bool removeFromStack = false)

+        {

+            var page = (PhoneApplicationPage) RootFrame.Content;

+            var service = page.NavigationService;

+            service.Navigate(param);

+            if (removeFromStack)

+            {

+                page.Dispatcher.BeginInvoke(() => service.RemoveBackEntry());

+            }

         }

-        private static AppViewModel context = null;

+        private static AppViewModel _context = null;

 

         public static AppViewModel AppContext

         {

             get

             {

                 // Delay creation of the view model until necessary

-                if (context == null) {

-                    context = new AppViewModel();

-                    context.Pages.Add(new PageViewModel(context) { RestUri = "/home?1=1" });

-                    context.Pages.Add(new PageViewModel(context) { RestUri = "/messages?1=1" });

+                if (_context == null) {

+                    _context = new AppViewModel();

+                    _context.Pages.Add(new PageViewModel(_context) { RestUri = "/home?1=1", Caption = "My feed"});

+                    _context.Pages.Add(new PageViewModel(_context) { RestUri = "/messages?1=1", Caption = "Last"});

+                    _context.Pages.Add(new PageViewModel(_context) { RestUri = "/messages?1=1&popular=1", Caption = "Top"});

+                    _context.Pages.Add(new PageViewModel(_context) { RestUri = "/messages?1=1&media=all", Caption = "Images" });

                 };

-                return context;

+                return _context;

             }

         }        

         /// <summary>

diff --git a/Juick/Classes/AccountManager.cs b/Juick/Classes/AccountManager.cs
index 8f8e366..4741992 100644
--- a/Juick/Classes/AccountManager.cs
+++ b/Juick/Classes/AccountManager.cs
@@ -1,53 +1,63 @@
 using System;

 using System.IO.IsolatedStorage;

 using System.Net;

+using System.Windows;

 using System.Windows.Controls;

 

 namespace Juick.Classes

 {

     public class AccountManager

     {

-        const string FileName = "account.xml";

-        public NetworkCredential Credentials

+        private string _userName;

+        private string _password;

+        

+        public string UserName

         {

             get

             {

-                string userName;

-                string password;

-                IsolatedStorageSettings.ApplicationSettings.TryGetValue<string>("user", out userName);

-                IsolatedStorageSettings.ApplicationSettings.TryGetValue<string>("password", out password);

-                return new NetworkCredential

-                           {

-                               UserName = userName,

-                               Password = password,

-                           };

+                if (_userName == null)

+                {

+                    IsolatedStorageSettings.ApplicationSettings.TryGetValue<string>("user", out _userName);    

+                }

+                return _userName;

             }

             set

             {

-                var creds = value;

-                if (creds != null)

-                {

-                    IsolatedStorageSettings.ApplicationSettings["user"] = value.UserName;

-                    IsolatedStorageSettings.ApplicationSettings["password"] = value.Password;

-                }

-                else

+                _userName = value;

+                IsolatedStorageSettings.ApplicationSettings["user"] = _userName;

+            }

+        }

+

+        public string Password

+        {

+            get

+            {

+                if (_password == null)

                 {

-                    IsolatedStorageSettings.ApplicationSettings["user"] = null;

-                    IsolatedStorageSettings.ApplicationSettings["password"] = null;

+                    IsolatedStorageSettings.ApplicationSettings.TryGetValue<string>("password", out _password);    

                 }

+                return _password;

+            }

+            set

+            {

+                _password = value;

+                IsolatedStorageSettings.ApplicationSettings["password"] = value;

             }

         }

 

-        public void SignIn(Page page, string login, string pass, Uri nextUri)

+        public bool IsAuthenticated

         {

-            Credentials = new NetworkCredential(login, pass);

-            page.NavigationService.Navigate(nextUri);

-            page.Dispatcher.BeginInvoke(() => page.NavigationService.RemoveBackEntry());

+            get { 

+                bool authenticated;

+                IsolatedStorageSettings.ApplicationSettings.TryGetValue<bool>("authenticated", out authenticated);

+                return authenticated;

+            }

+            set { IsolatedStorageSettings.ApplicationSettings["authenticated"] = value; }

         }

-

+        

         public void SignOut(Page page)

         {

-            Credentials = null;

+            IsAuthenticated = false;

             page.NavigationService.Navigate(new Uri("/LoginView.xaml", UriKind.Relative));

             page.Dispatcher.BeginInvoke(() => page.NavigationService.RemoveBackEntry());

         }

diff --git a/Juick/Controls/MessageList.xaml b/Juick/Controls/MessageList.xaml
index 7a7d823..afa6c69 100644
--- a/Juick/Controls/MessageList.xaml
+++ b/Juick/Controls/MessageList.xaml
@@ -14,7 +14,7 @@
     d:DesignHeight="480" d:DesignWidth="480">
 
     <Grid x:Name="LayoutRoot">
-        <toolkit:LongListSelector x:Name="longList" Margin="0, 0, -12, 0"
+        <toolkit:LongListSelector Margin="0, 0, -12, 0"
                  ItemsSource="{Binding Items}" IsFlatList="true">
             <i:Interaction.Triggers>
                 <i:EventTrigger EventName="Link">
diff --git a/Juick/Juick.csproj b/Juick/Juick.csproj
index ebe128c..33fbd5c 100644
--- a/Juick/Juick.csproj
+++ b/Juick/Juick.csproj
@@ -103,9 +103,11 @@
       <DependentUpon>ThreadView.xaml</DependentUpon>

     </Compile>

     <Compile Include="ViewModels\AppViewModel.cs" />

+    <Compile Include="ViewModels\LoginViewModel.cs" />

     <Compile Include="ViewModels\PageViewModel.cs" />

     <Compile Include="ViewModels\PostItem.cs" />

     <Compile Include="ViewModels\ThreadViewModel.cs" />

+    <Compile Include="ViewModels\Validation\DataViewModelBase.cs" />

     <Compile Include="ViewModels\ViewModelBase.cs" />

   </ItemGroup>

   <ItemGroup>

diff --git a/Juick/LoginView.xaml b/Juick/LoginView.xaml
index ad1d70c..004580a 100644
--- a/Juick/LoginView.xaml
+++ b/Juick/LoginView.xaml
@@ -3,15 +3,19 @@
     xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"

     xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"

     xmlns:phone="clr-namespace:Microsoft.Phone.Controls;assembly=Microsoft.Phone"

-    xmlns:shell="clr-namespace:Microsoft.Phone.Shell;assembly=Microsoft.Phone"

+    xmlns:phoneshell="clr-namespace:Microsoft.Phone.Shell;assembly=Microsoft.Phone"

     xmlns:d="http://schemas.microsoft.com/expression/blend/2008"

     xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"

+    xmlns:viewModels="clr-namespace:Juick.ViewModels"

     FontFamily="{StaticResource PhoneFontFamilyNormal}"

     FontSize="{StaticResource PhoneFontSizeNormal}"

     Foreground="{StaticResource PhoneForegroundBrush}"

     SupportedOrientations="Portrait" Orientation="Portrait"

     mc:Ignorable="d" d:DesignHeight="768" d:DesignWidth="480"

-    shell:SystemTray.IsVisible="True" Loaded="PhoneApplicationPage_Loaded">

+    phoneshell:SystemTray.IsVisible="True">

+  <phone:PhoneApplicationPage.DataContext>

+    <viewModels:LoginViewModel />

+  </phone:PhoneApplicationPage.DataContext>

 

     <!--LayoutRoot is the root grid where all page content is placed-->

     <Grid x:Name="LayoutRoot" Background="Transparent">

@@ -28,24 +32,26 @@
 

         <!--ContentPanel - place additional content here-->

         <Grid x:Name="ContentPanel" Grid.Row="1" Margin="12,0,12,0">

-            <TextBlock Height="30" HorizontalAlignment="Left" Margin="37,119,0,0" Name="textBlock1" Text="Username" VerticalAlignment="Top" />

-            <TextBox Height="72" HorizontalAlignment="Left" Margin="25,155,0,0" Name="textBox1" Text="{Binding UserName}" VerticalAlignment="Top" Width="409" />

-            <TextBlock Height="30" HorizontalAlignment="Left" Margin="37,246,0,0" Name="textBlock2" Text="Password" VerticalAlignment="Top" />

-            <Button Content="Sign in" Height="72" HorizontalAlignment="Left" Margin="274,360,0,0" Name="button1" VerticalAlignment="Top" Width="160" Click="button1_Click" />

-            <PasswordBox Height="72" HorizontalAlignment="Left" Password="{Binding Password}" Margin="25,282,0,0" Name="textBox2" VerticalAlignment="Top" Width="409" />

+            <TextBlock Height="30" HorizontalAlignment="Left" Margin="37,119,0,0" Text="Username" VerticalAlignment="Top" />

+            <TextBox Height="72" HorizontalAlignment="Left" Margin="25,155,0,0" Text="{Binding Username, Mode=TwoWay}" VerticalAlignment="Top" Width="409" />

+            <TextBlock Height="30" HorizontalAlignment="Left" Margin="37,246,0,0" Text="Password" VerticalAlignment="Top" />

+            <Button Content="Sign in" Height="72" HorizontalAlignment="Left" Margin="274,360,0,0" 

+                    VerticalAlignment="Top" Width="160" Command="{Binding SignInCommand}" />

+            <PasswordBox Height="72" HorizontalAlignment="Left" Password="{Binding Password, Mode=TwoWay}" 

+                         Margin="25,282,0,0" VerticalAlignment="Top" Width="409" />

         </Grid>

     </Grid>

  

     <!--Sample code showing usage of ApplicationBar-->

     <!--<phone:PhoneApplicationPage.ApplicationBar>

-        <shell:ApplicationBar IsVisible="True" IsMenuEnabled="True">

-            <shell:ApplicationBarIconButton IconUri="/Images/appbar_button1.png" Text="Button 1"/>

-            <shell:ApplicationBarIconButton IconUri="/Images/appbar_button2.png" Text="Button 2"/>

-            <shell:ApplicationBar.MenuItems>

-                <shell:ApplicationBarMenuItem Text="MenuItem 1"/>

-                <shell:ApplicationBarMenuItem Text="MenuItem 2"/>

-            </shell:ApplicationBar.MenuItems>

-        </shell:ApplicationBar>

+        <phoneshell:ApplicationBar IsVisible="True" IsMenuEnabled="True">

+            <phoneshell:ApplicationBarIconButton IconUri="/Images/appbar_button1.png" Text="Button 1"/>

+            <phoneshell:ApplicationBarIconButton IconUri="/Images/appbar_button2.png" Text="Button 2"/>

+            <phoneshell:ApplicationBar.MenuItems>

+                <phoneshell:ApplicationBarMenuItem Text="MenuItem 1"/>

+                <phoneshell:ApplicationBarMenuItem Text="MenuItem 2"/>

+            </phoneshell:ApplicationBar.MenuItems>

+        </phoneshell:ApplicationBar>

     </phone:PhoneApplicationPage.ApplicationBar>-->

 

 </phone:PhoneApplicationPage>

diff --git a/Juick/LoginView.xaml.cs b/Juick/LoginView.xaml.cs
index 098275b..06ac58c 100644
--- a/Juick/LoginView.xaml.cs
+++ b/Juick/LoginView.xaml.cs
@@ -1,5 +1,6 @@
 using System.Linq;

 using System.Windows;

+using Juick.ViewModels;

 using Microsoft.Phone.Controls;

 using System;

 

@@ -10,27 +11,18 @@ namespace Juick
         public LoginView()

         {

             InitializeComponent();

-            DataContext = App.AppContext.Account.Credentials;

+            Loaded += (sender, args) =>

+                          {

+                              while (NavigationService.BackStack.Any())

+                                  NavigationService.RemoveBackEntry();

+                          };

         }

 

-        private Uri nextUri;

-

         protected override void OnNavigatedTo(System.Windows.Navigation.NavigationEventArgs e)

         {

-            nextUri = NavigationContext.QueryString.ContainsKey("FileId")

+            ((LoginViewModel)DataContext).NextUri = NavigationContext.QueryString.ContainsKey("FileId")

                 ? new Uri(string.Format("/NewPostView.xaml?FileId={0}", NavigationContext.QueryString["FileId"]), UriKind.Relative)

                 : new Uri("/MainPage.xaml", UriKind.Relative);

         }

-

-        private void button1_Click(object sender, RoutedEventArgs e)

-        {

-            App.AppContext.Account.SignIn(this, textBox1.Text, textBox2.Password, nextUri);

-        }

-

-        private void PhoneApplicationPage_Loaded(object sender, RoutedEventArgs e)

-        {

-            while (NavigationService.BackStack.Any())

-                NavigationService.RemoveBackEntry();

-        }

     }

 }
\ No newline at end of file
diff --git a/Juick/MainPage.xaml b/Juick/MainPage.xaml
index 2e40d0f..45e1ff9 100644
--- a/Juick/MainPage.xaml
+++ b/Juick/MainPage.xaml
@@ -22,14 +22,19 @@
             <RowDefinition Height="*" />

         </Grid.RowDefinitions>

         

-        <controls:Pivot Title="juick" Grid.Row="1">

-            <controls:PivotItem Header="My feed" Margin="0, -5, 0, 0">

-                <usercontrols:MessageList x:Name="Home" />

-            </controls:PivotItem>

-            <controls:PivotItem Header="Last" Margin="0, -5, 0, 0">

-                <usercontrols:MessageList x:Name="Last"/>

-            </controls:PivotItem>            

+        <controls:Pivot x:Name="Pages" Title="juick" Grid.Row="1" ItemsSource="{Binding Pages}">

+          <controls:Pivot.HeaderTemplate>

+            <DataTemplate>

+              <TextBlock Text="{Binding Caption}"></TextBlock>

+            </DataTemplate>

+          </controls:Pivot.HeaderTemplate>

+          <controls:Pivot.ItemTemplate>

+            <DataTemplate>

+              <usercontrols:MessageList />

+            </DataTemplate>

+          </controls:Pivot.ItemTemplate>

         </controls:Pivot>

+        

     </Grid>

     <phone:PhoneApplicationPage.ApplicationBar>

         <phoneshell:ApplicationBar IsVisible="True" IsMenuEnabled="True">

diff --git a/Juick/MainPage.xaml.cs b/Juick/MainPage.xaml.cs
index a634e7f..1c76ee1 100644
--- a/Juick/MainPage.xaml.cs
+++ b/Juick/MainPage.xaml.cs
@@ -4,10 +4,12 @@ using System.Text;
 using System.Windows;

 using System.Windows.Controls;

 using System.Windows.Data;

+using Juick.Controls;

 using Microsoft.Phone.Controls;

 using Microsoft.Phone.Notification;

 using Microsoft.Phone.Shell;

 using Juick.ViewModels;

+using RestSharp;

 

 namespace Juick

 {

@@ -23,7 +25,7 @@ namespace Juick
             //string channelName = "JuickChannel"; // unused variable

 

             InitializeComponent();

-            

+

             /*      // Try to find the push channel.

                   pushChannel = HttpNotificationChannel.Find(channelName);

 

@@ -61,33 +63,32 @@ namespace Juick
 

                   }*/

 

-            // Set the data context of the listbox control to the sample data

             DataContext = App.AppContext;

-            Home.DataContext = ((AppViewModel)DataContext).Pages[0];

-            Last.DataContext = ((AppViewModel)DataContext).Pages[1];

+

             Loaded += (o, args) =>

-            {

-                var progressIndicator = SystemTray.ProgressIndicator;

+                          {

+                              Pages.SelectedIndex = 0;

+                              var progressIndicator = SystemTray.ProgressIndicator;

 

-                if (progressIndicator != null)

-                {

-                    return;

-                }

+                              if (progressIndicator != null)

+                              {

+                                  return;

+                              }

 

-                progressIndicator = new ProgressIndicator();

+                              progressIndicator = new ProgressIndicator();

 

-                SystemTray.SetProgressIndicator(this, progressIndicator);

+                              SystemTray.SetProgressIndicator(this, progressIndicator);

 

-                Binding binding = new Binding("IsDataLoading") { Source = DataContext };

+                              Binding binding = new Binding("IsDataLoading") { Source = DataContext };

 

-                BindingOperations.SetBinding(

-                    progressIndicator, ProgressIndicator.IsVisibleProperty, binding);

+                              BindingOperations.SetBinding(

+                                  progressIndicator, ProgressIndicator.IsVisibleProperty, binding);

 

-                binding = new Binding("IsDataLoading") { Source = DataContext };

+                              binding = new Binding("IsDataLoading") { Source = DataContext };

 

-                BindingOperations.SetBinding(

-                    progressIndicator, ProgressIndicator.IsIndeterminateProperty, binding);

-            };

+                              BindingOperations.SetBinding(

+                                  progressIndicator, ProgressIndicator.IsIndeterminateProperty, binding);

+                          };

         }

 

         protected override void OnNavigatedTo(System.Windows.Navigation.NavigationEventArgs e)

@@ -102,7 +103,7 @@ namespace Juick
             // Ensure that there is at least one key in the query string, and check 

             // whether the "FileId" key is present.

 

-            navigateUri = string.IsNullOrEmpty(App.AppContext.Account.Credentials.UserName) ? loginUriPart : newPostUriPart;

+            navigateUri = App.AppContext.Account.IsAuthenticated ? newPostUriPart : loginUriPart;

             if (queryStrings.ContainsKey("FileId"))

             {

                 FileId = queryStrings["FileId"];

@@ -112,6 +113,11 @@ namespace Juick
             {

                 NavigationService.Navigate(new Uri(navigateUri, UriKind.Relative));

             }

+            App.AppContext.Client.Authenticator = new HttpBasicAuthenticator(App.AppContext.Account.UserName, App.AppContext.Account.Password);

+            if (App.AppContext.Account.IsAuthenticated)

+                foreach (var page in ((AppViewModel)DataContext).Pages)

+                    page.RefreshData();

+            

         }

 

         void PushChannel_ChannelUriUpdated(object sender, NotificationChannelUriEventArgs e)

@@ -163,10 +169,11 @@ namespace Juick
 

         private void ApplicationBarIconButtonClick(object sender, EventArgs e)

         {

-            App.AppContext.Pages[0].Items.Clear();

-            App.AppContext.Pages[1].Items.Clear();

-            App.AppContext.Pages[0].RefreshData();

-            App.AppContext.Pages[1].RefreshData();

+            foreach (var page in App.AppContext.Pages)

+            {

+                page.Items.Clear();

+                page.RefreshData();

+            }

         }

 

         private void ApplicationBarMenuItemClick(object sender, EventArgs e)

diff --git a/Juick/NewPostView.xaml.cs b/Juick/NewPostView.xaml.cs
index 4f3cc06..dbc45c4 100644
--- a/Juick/NewPostView.xaml.cs
+++ b/Juick/NewPostView.xaml.cs
@@ -43,7 +43,7 @@ namespace Juick
             // whether the "FileId" key is present.

             if (queryStrings.ContainsKey("FileId"))

             {

-                App.AppContext.Client.Authenticator = new HttpBasicAuthenticator(App.AppContext.Account.Credentials.UserName, App.AppContext.Account.Credentials.Password);

+                App.AppContext.Client.Authenticator = new HttpBasicAuthenticator(App.AppContext.Account.UserName, App.AppContext.Account.Password);

                 // Retrieve the picture from the media library using the FileID

                 // passed to the application.

                 MediaLibrary library = new MediaLibrary();

diff --git a/Juick/ViewModels/LoginViewModel.cs b/Juick/ViewModels/LoginViewModel.cs
new file mode 100644
index 0000000..95528fe
--- /dev/null
+++ b/Juick/ViewModels/LoginViewModel.cs
@@ -0,0 +1,72 @@
+using System;
+using System.Net;
+using System.Windows;
+using Juick.Classes;
+using Juick.ViewModels.Validation;
+using RestSharp;
+
+namespace Juick.ViewModels
+{
+    public class LoginViewModel : DataViewModelBase 
+    {
+        private string _username;
+        private string _password;
+        private DelegateCommand<RoutedEventArgs> _signInCommand;
+
+        public string Username
+        {
+            get
+            {
+                return _username ?? (_username = App.AppContext.Account.UserName);
+            }
+            set
+            {
+                _username = value;
+                NotifyPropertyChanged("Username");
+            }
+        }
+
+        public string Password
+        {
+            get
+            {
+                return _password ?? (_password = App.AppContext.Account.Password);
+            }
+            set
+            {
+                _password = value;
+                NotifyPropertyChanged("Password");
+            }
+        }
+
+        public Uri NextUri { get; set; }
+
+        public DelegateCommand<RoutedEventArgs> SignInCommand
+        {
+            get
+            {
+                return _signInCommand ?? (_signInCommand = new DelegateCommand<RoutedEventArgs>(CheckAuth, () => true));
+            }
+        }
+
+        public void CheckAuth(RoutedEventArgs e)
+        {
+            App.AppContext.Client.Authenticator = new HttpBasicAuthenticator(Username, Password);
+            App.AppContext.Client.ExecuteAsync(new RestRequest("/post", Method.POST), response =>
+                                                                             {
+                                                                                 if (response.StatusCode ==
+                                                                                     HttpStatusCode.BadRequest)
+                                                                                 {
+                                                                                     App.AppContext.Account.UserName = Username;
+                                                                                     App.AppContext.Account.Password = Password;
+                                                                                     App.AppContext.Account.IsAuthenticated = true;
+                                                                                     ((App)Application.Current).NavigateTo(NextUri, true);
+                                                                                 }
+                                                                                 else
+                                                                                 {
+                                                                                     AddError("Username", "Invalid username or password", false);
+                                                                                 }
+                                                                             });
+        }
+    }
+}
diff --git a/Juick/ViewModels/PageViewModel.cs b/Juick/ViewModels/PageViewModel.cs
index 02f86ff..e398caf 100644
--- a/Juick/ViewModels/PageViewModel.cs
+++ b/Juick/ViewModels/PageViewModel.cs
@@ -31,11 +31,10 @@ namespace Juick.ViewModels
             set
             {
                 _restUri = value;
-                RefreshData();
             }
         }
 
-        public virtual string Caption { get { return "juick"; } }
+        public virtual string Caption { get; set; }
 
         public ObservableCollection<PostItem> Items { get; private set; }
 
@@ -70,7 +69,6 @@ namespace Juick.ViewModels
             }
 
             var request = new RestRequest(requestUri);
-            _context.Client.Authenticator = new HttpBasicAuthenticator(_context.Account.Credentials.UserName, _context.Account.Credentials.Password);
             _context.Client.ExecuteAsync<List<Message>>(request, response =>
             {
                 _context.IsDataLoading = false;
diff --git a/Juick/ViewModels/Validation/DataViewModelBase.cs b/Juick/ViewModels/Validation/DataViewModelBase.cs
new file mode 100644
index 0000000..dcbf34b
--- /dev/null
+++ b/Juick/ViewModels/Validation/DataViewModelBase.cs
@@ -0,0 +1,44 @@
+using System;
+using System.Collections.Generic;
+using System.ComponentModel;
+
+namespace Juick.ViewModels.Validation
+{
+    public class DataViewModelBase : ViewModelBase, IDataErrorInfo
+    {
+
+        private readonly Dictionary<String, List<String>> _errors =
+           new Dictionary<string, List<string>>();
+
+        // Adds the specified error to the errors collection if it is not already 
+        // present, inserting it in the first position if isWarning is false. 
+        public void AddError(string propertyName, string error, bool isWarning)
+        {
+            if (!_errors.ContainsKey(propertyName))
+                _errors[propertyName] = new List<string>();
+
+            if (_errors[propertyName].Contains(error)) return;
+            if (isWarning) _errors[propertyName].Add(error);
+            else _errors[propertyName].Insert(0, error);
+        }
+
+        // Removes the specified error from the errors collection if it is present. 
+        public void RemoveError(string propertyName, string error)
+        {
+            if (!_errors.ContainsKey(propertyName) || !_errors[propertyName].Contains(error)) return;
+            _errors[propertyName].Remove(error);
+            if (_errors[propertyName].Count == 0) _errors.Remove(propertyName);
+        }
+
+        public string Error { get { throw new NotImplementedException(); } }
+
+        public string this[string columnName]
+        {
+            get
+            {
+                return (!_errors.ContainsKey(columnName) ? null :
+                    String.Join(Environment.NewLine, _errors[columnName]));
+            }
+        }
+    }
+}