OmegaMan's Musings

<Grid>
    <Rectangle Fill="Blue" Width="100" Height="100" HorizontalAlignment="Right" VerticalAlignment="Top" Margin="0,10,0,0"  />
</Grid>

<Rectangle ...>
   <Rectangle.RenderTransform>
       <TranslateTransform X="0" Y="0" />
   </Rectangle.RenderTransform>
 </Rectangle>

What we need now is to, adjust what we have, but start it out of sight to the right *side* of the screen. To achieve this we will change the above translate transform coordinates to instead move the X value and have the start in the off page position. To do that change the existing to this:

<TranslateTransform X="100" Y="0" />

Play with it in design mode by changing the X and Y values and not how it moves around from its initial anchor point.

Set Associative Values

Currently our panel has a Width of 100 and we want to move it off the screen, *and move it back* by that amount; an offset slide amount. What we will do is in the Grid Resource section, *though it could be placed in the page’s Resource section*, is a constant which we will apply to the panel’s Width and the X as an initial offset value.

    <Grid>
        <Grid.Resources>
            <system:Double x:Key="SlideOffSet">100</system:Double>
        </Grid.Resources>

        <Rectangle Width="{StaticResource SlideOffSet}" Height="100" HorizontalAlignment="Right" VerticalAlignment="Top" Margin="0,10,0,0" >
            <Rectangle.RenderTransform>
                <TranslateTransform X="{StaticResource SlideOffSet}" Y="0" />
            </Rectangle.RenderTransform>
        </Rectangle>
    </Grid>

Check the design mode…it should still be off the screen and in the same dimensions as specified in the previous section.

Add a ToggleButton To Change States

We add a toggle button above the Rectangle panel because we want the panel to be drawn last; so to have it have the highest Zindex. So when it slides in, it will be above all other controls.

<Grid>
    <ToggleButton Height="30" Width="60" Margin="0,20,0,20" x:Name="SlideState">
        <TextBlock Text="{Binding IsChecked, ElementName=SlideState}"
                       FontSize="18" 
                       VerticalAlignment="Center" HorizontalAlignment="Center"  >
        </TextBlock>
    </ToggleButton>

    <Rectangle ...

The Animation Magic To Move It In and Out

To do this we will use Storyboards which when triggered will change the panel’s TranslateTransform X value to and from our slide offset. Go ahead and add the StoryBoards below under the SlideOffset setting in the Resources section.

<Storyboard x:Key="SlideRight">
    <DoubleAnimation Storyboard.TargetProperty="(UIElement.RenderTransform).(TranslateTransform.X)"
                     From="0" To="{StaticResource SlideOffSet}"
                     Duration="0:0:0.3" />
</Storyboard>

<Storyboard x:Key="SlideLeft">
    <DoubleAnimation Storyboard.TargetProperty="(UIElement.RenderTransform).(TranslateTransform.X)"
                     From="{StaticResource SlideOffSet}" To="0" 
                     Duration="0:0:0.3" />
</Storyboard>

The above code basically changes the target control, in our case the Rectangle, and shifts the X transform anchor value.

Initiate The Dark Move Magic On Button Click

Believe it or not, but we are not finished. The final bit of code has us, again, putting code in the Resource section which will define a style for our Rectangle.

This style is a trigger which is based, bound, off of the value of the IsChecked and depending on its value, initiates the SlideLeft (to move into view) and the SlideRight to move it back off the screen.

<Style TargetType="{x:Type Rectangle}">
    <Style.Triggers>
        <DataTrigger Binding="{Binding IsChecked, ElementName=SlideState}" Value="True">
            <DataTrigger.EnterActions>
                <BeginStoryboard Storyboard="{StaticResource SlideLeft}" />
            </DataTrigger.EnterActions>
            <DataTrigger.ExitActions>
                <BeginStoryboard Storyboard="{StaticResource SlideRight}" />
            </DataTrigger.ExitActions>
        </DataTrigger>
    </Style.Triggers>
</Style>

Final Thoughts & Code

On the following page (#2) is the full code for your perusal, with no changes from above. For me learning how to position a panel off the screen and then move it was trial and error of internet searches and reading StackOverflow posts. Each component on its own is understandable, but has to be consumed in a certain order. This post is that order in which I would have liked to have read first.

To further your understanding of this see Transforms Overview on Microsoft’s documentation.

Full Code on Page 2 —-(*if link to page #2 is not seen below, load the whole article and scroll down*)——–>

Using Cisco AnyConnect In A Virtual Machine is Problematic. This post details how to enable that operation from within the virtual machine.

---

ISSUE

When one attempts to run the vpn in a virtual they are presented with:

The actual error is:

VPN establishment capability from a remote desktop is disabled. A VPN connection will not be established.VPN establishment capability from a remote desktop is disabled. A VPN connection will not be established.

---

Cisco Resolution (InComplete)

Cisco advises to resolve by changing the value WindowsVPNEstablishment to AllowRemoteUsers and references a now defunct web page.

How to enable Cisco Anyconnect VPN through Remote Desktop

Unfortunately it does not specify if that is on the server or client.

Resolution (Client)

To resolve the issue one has to intercept a downloaded file CHS-TwoFactor-VPN_client-profile.xml downloaded/modified during connection and change 1 or more settings in this file. This method was proposed by the post Bypassing Cisco AnyConnects profile settings by Joao. His method was to create a C# filewatcher which when the XML file changed, to replace it with a settings file that had WindowsVPNEstablishment as well as WindowsLogonEnforcement commented out. But I found that his code/methodology had a couple of problematic issues which could cause it to fail. Specifically the value of the key WindowsVPNEstablishment needs to be set to AllowRemoteUsers and not just commented out I document my solution below.

Xml Changes

Before

<WindowsLogonEnforcement>SingleLocalLogon</WindowsLogonEnforcement>
<WindowsVPNEstablishment>LocalUsersOnly</WindowsVPNEstablishment>

After

<WindowsLogonEnforcement>SingleLocalLogon</WindowsLogonEnforcement>
<WindowsVPNEstablishment>AllowRemoteUsers</WindowsVPNEstablishment>

Note that I do not change the WindowsLogonEnforcement as advised by Joao because I am surmising that I only have one connection to coporate at a time which is in the Virtual Machine. I believe that this setting is for multiple connections(?) … so if you run into further issues, that may need to be addressed.

C# Code

Design Considerations

• C# program which can be compiled outside of Visual Studio by C:\Windows\Microsoft.NET\Framework64\v4.0.30319\csc.exe {filename}.cs
• Deletes the existing initial XML file as first step. Requiring a new download by the CISCO process.
• Watch the directory %ProgramData%\Cisco\Cisco AnyConnect Secure Mobility Client\Profile for changes.
• When change of Created is thrown, delete downloaded file and replace with backup file in the same directory which has aformentioned xml changes ready to go.

class Program
{
    static string FileName => "CHS-TwoFactor-VPN_client-profile";
    static string Directory => @"C:\ProgramData\Cisco\Cisco AnyConnect Secure Mobility Client\Profile";
    static string PathedFileName => $@"{Directory}\{FileName}.xml";

    static bool HasReplaced = false;
    static void Main(string[] args)
    {
        Console.WriteLine($"Watcher started on Directory{Environment.NewLine}{Directory}");

        DeleteFile();

        var watcher = new FileSystemWatcher(Directory);
        watcher.EnableRaisingEvents = true;

        watcher.Created += Watcher_Changed;
        watcher.Changed += Watcher_Changed;
        watcher.Deleted += Watcher_Changed;

        while (!HasReplaced)
            System.Threading.Thread.Sleep(50);

        watcher.Created -= Watcher_Changed;
        watcher.Changed -= Watcher_Changed;
        watcher.Deleted -= Watcher_Changed;

        watcher = null;
    }

    private static void Watcher_Changed(object sender, FileSystemEventArgs e)
    {
        if ((e.ChangeType == WatcherChangeTypes.Created) || (e.ChangeType == WatcherChangeTypes.Changed))
        {
            switch (e.ChangeType)
            {
                case WatcherChangeTypes.Created: Console.WriteLine("Created Event"); break;
                case WatcherChangeTypes.Changed: Console.WriteLine("Changed Event"); break;
            }
            ReplaceFile();
        }
    }

    static void ReplaceFile()
    {
        DeleteFile();

        File.Copy($@"{Directory}\{FileName}.bak", $@"{Directory}\{FileName}.xml"); 

        HasReplaced = true;
        Console.WriteLine("File Replaced");
    }

    static void DeleteFile()
    {
        if (File.Exists(PathedFileName))
        {
            File.Delete(PathedFileName);
            Console.WriteLine($"Removing {FileName}.xml");
        }
    }
}

---

Usage

XML File

1. In the %ProgramData%\Cisco\Cisco AnyConnect Secure Mobility Client\Profile create a backup file named CHS-TwoFactor-VPN_client-profile.bak with the changes mentione in the XML Changes section.

This is used by the C# program to replace the downloaded file from Cisco at the right moment.

C# File

1. Copy the exe (only ignore other uneeded files) generated into a directory on the virtual machine.
2. Create a shortcut on the desktop to the file. (in Explorer Drag exe file while holding CTRL-Shift to create a link).
3. Right Click the Link on the desktop and Run as administrator.
4. Login through AnyConnect.

Note that the program will show status and if you want to see that status, run the program from a command shell which is run as an administrator.

Not finding a satisfactory method to find invalid Azure Container names, I wrote my own easier (?) to read regex pattern for .Net.

^                       # Anchor; beginning of line. 
(?!.+--)                # String ahead does not contain two dashes 
(?!^-)                  # String ahead does not start with a dash 
(\$root|[a-z\d-]{3,63}) # Either literal root or a combination of lower case. 
$                       # Anchor; end of line

 

Using a negative look ahead convention (which does not match anything) to handle the double dash situation makes it easier to read.

The first rule says from the beginning of the line, there should not be two dashes or to start with a dash. Once valid, then either match the literal text “$root” or then match only lower case letters, numbers or a dash for a total of three characters to 63 characters.

Remember to run the above pattern with IgnorePatternWhiteSpace, which allows us to comment it. Or run without any option by specifying it on one line:

^(?!.+--)(?!^-)(\$root|[a-z\d-]{3,63})$

Here are the rules for Container names:

Valid naming for a Container in Azure Blob Storage.

1.  3 to 63 Characters

2.  Starts With Letter or Number

3.  Letters, Numbers, and Dash (-)

4.  Every Dash (-) Must Be Immediately Preceded and Followed by a Letter or Number

5.  All letters in a container name must be lowercase.

When creating a C# WCF service (version .Net 3.0 and above) there may be a value in identifying the clients (consumers) which a web service is providing operational support to. This article demonstrates in C# and config Xml how to have clients identify themselves and pass pertinent information within the soap message’s header. That information in turn will be processed by the Web Service accordingly.

Client Identifies Itself

The goal here is to have the client provide some sort of information which the server can use to determine who is sending the message. The following C# code will add a header named `ClientId`:

var cl = new ActiveDirectoryClient();

var eab = new EndpointAddressBuilder(cl.Endpoint.Address);

eab.Headers.Add( AddressHeader.CreateAddressHeader("ClientId",       // Header Name
                                                   string.Empty,     // Namespace
                                                    "OmegaClient")); // Header Value
cl.Endpoint.Address = eab.ToEndpointAddress();

// Now do an operation provided by the service.
cl.ProcessInfo("ABC");

What that code is doing is adding an endpoint header named `ClientId` with a value of `OmegaClient` to be inserted into the soap header without a namespace.

Custom Header in Client’s Config File

There is an alternate way of doing a custom header. That can be achieved in the Xml config file of the client where all messages sent by specifying the custom header as part of the endpoint as so:

<configuration>
    <startup> 
        <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.5" />
    </startup>
    <system.serviceModel>
        <bindings>
            <basicHttpBinding>
                <binding name="BasicHttpBinding_IActiveDirectory" />
            </basicHttpBinding>
        </bindings>
        <client>
          <endpoint address="http://localhost:41863/ActiveDirectoryService.svc"
              binding="basicHttpBinding" bindingConfiguration="BasicHttpBinding_IActiveDirectory"
              contract="ADService.IActiveDirectory" name="BasicHttpBinding_IActiveDirectory">
            <headers>
              <ClientId>Console_Client</ClientId>
            </headers>
          </endpoint>
        </client>
    </system.serviceModel>
</configuration>

The above config file is from a .Net 4.5 client.

Server Identifies Client Request

Finally the web service will read the custom header and distinquish between any WCF client and process it accordingly.

var opContext = OperationContext.Current; // If this is null, is this code in an async block? If so, extract it before the async call.

var rq = opContext.RequestContext; 

var headers = rq.RequestMessage.Headers;

int headerIndex = headers.FindHeader("ClientId", string.Empty);

var clientString = (headerIndex < 0) ? "UNKNOWN" : headers.GetHeader<string>(headerIndex);

At some point one needs to view all the properties of an instance outside of a debugger such as for a unit test reporting the results or possibly a console application informing its status to the output. To achieve the results one overrides `ToString()` and by hand writes the information of the instance’s properties and their values to the output string. This can become cumbersome if the class instance is changing or when one realizes that the time ratio of creating such a reporting operation verses the size of what is being reported can lead to valuable time taken away from the developer.

This article demonstrates a C# extension which will take any class instance and report any non null properties as well as any string lists. The goal of the report is to provide information on the standard properties (string, int, datetime, etc) as well as string lists and ignores any  complex objects. Also provided is the ability to show the non-public properties.

For the resulting visual list, the code lines up the output report in key value pairs where the largest character count key name (the property name reported) will be spaced out along with all other names.

Here is an example result of a class instance with differing properties. Note that `MemberOfAsList` is a List<string> property which internally splits out the property `MemberOf` string (by its comma) into a list. This extension shows the list as a `string__abENT__#46;join` of `__abENT__quot;, __abENT__quot;`.

DistinguishedName : CN=Write Frank,OU=Test,OU=Acme Industries,DC=amce-co,DC=acme,DC=net
CommonName        : Write Frank Lloyd
MemberOf          : CN=2042_Identity,CN=UserIdentities,CN=AlphaVision,DC=acme-co,DC=acme,DC=net
MemberOfAsList    : CN=2042_Identity, CN=UserIdentities, CN=AlphaVision, DC=acme-co, DC=acme, DC=net
otherTelephone    : 303-555-555
Name              : Wright Frank
WhenChanged       : 3/17/2014 9:04:06 PM
LogonCount        : 0

Extension Method

The following is an extension method whose goal is to reflect the type being passed in, determine the sizing of the data for output and then reports the properties each on a different line. String lists values are specified by a `,` (comma and space) separator between each value.

public static string ReportAllProperties<T>(this T instance) where T : class
{

    if (instance == null)
        return string.Empty;

    var strListType = typeof(List<string>);
    var strArrType  = typeof(string[]);

    var arrayTypes   = new[] { strListType, strArrType };
    var handledTypes = new[] { typeof(bool), typeof(Int32), typeof(String), typeof(DateTime), typeof(double), typeof(decimal), strListType, strArrType };

    var validProperties = instance.GetType()
                                  .GetProperties(BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic)
                                  .Where(prop => handledTypes.Contains(prop.PropertyType))
                                  .Where(prop => prop.GetValue(instance, null) != null)
                                  .ToList();

    var format = string.Format("{{0,-{0}}} : {{1}}", validProperties.Max(prp => prp.Name.Length));

    return string.Join(
             Environment.NewLine,
             validProperties.Select(prop => string.Format(format, 
                                                          prop.Name,
                                                          (arrayTypes.Contains(prop.PropertyType) ? string.Join(", ", (IEnumerable<string>)prop.GetValue(instance, null))
                                                                                                  : prop.GetValue(instance, null)))));
}

Usage

public override string ToString()
{
    return ( this.ReportAllProperties() );
}

Test & Results

var test = new MyClass("Admin") { Name = "Omegaman", 
                                  ID = 1,  
                                  StartDate = DateTime.Now,
                                  AccessPoints = new List<string> { "Alpha", "Beta", "Gamma" },
                                  WeekDays = new string[]{ "Mon", "Tue" }
                                 };

 Console.WriteLine (test.ToString());

/*
Name         : Omegaman
ID           : 1
Role         : Admin
AccessPoints : Alpha, Beta, Gamma
WeekDays     : Mon, Tue
StartDate    : 3/18/2014 12:16:07 PM
*/

....

public class MyClass
{
    public string Name               { get; set; }
    public int ID                    { get; set; }
    private string Role              { get; set; }
    public List<string> AccessPoints { get; set; }
    public string[] WeekDays         { get; set; }    
    public DateTime StartDate        { get; set; }

    public MyClass(string role)
    {
        Role = role;
    }

    public override string ToString()
    {
       return ( this.ReportAllProperties() );
    }

}

Done!

I recently had a need to determine if a sequence of integers was solid, not broken, and whether it contained a gap of any missing numbers to report to the end user. I researched the issue and was dismayed that the examples found on the internet seemed to have unnecessary overheads of copied arrays or other artifacts and were too cumbersome for my needs. From that I wrote these C# extensions which work for any .Net above 3.5. Below I document the extension methods to get the missing numbers of a sequence, quickly determine if a sequence is broken and finally report where the existing numbers before the break of the sequence. See the end for the whole extension class for easier copying.

Problem Definition

If one has a set of numbers say

{ 2, 4, 7, 9 }

it has a broken sequence because there are missing numbers from the set 2-9. Those missing numbers are:

{ 3, 5, 6, 8 }

Find Missing Numbers In a Sequence

This method is the one I created first. It uses the Linq Aggregate extension to enumerate over the numbers in the set. If there is a gap which is greater than 1 between the numbers (the difference below is > 0 but same concept) then it reports the numbers missing between the two.

public static IEnumerable<int> SequenceFindMissings(this IList<int> sequence)
{

    var missing = new List<int>();

    if ((sequence != null) && (sequence.Any()))
    {
        sequence.Aggregate((seed, aggr) =>
                            {
                                var diff = (aggr - seed) - 1;

                                if (diff > 0)
                                    missing.AddRange(Enumerable.Range((aggr - diff), diff));

                                return aggr;
                            });
    }

    return missing;
}

Quickly Determine Broken Sequence

Is the sequence broken from the first number to the last in the set?

public static bool IsSequenceBroken(this IEnumerable<int> sequence)
{
    bool broken = false;

    if (sequence != null) 
    {
        var sequenceAsList = sequence.ToList();

        if (sequenceAsList.Any())
        {
            int lastValue = sequence.First();

            broken = sequence.Any(value =>
                                    {
                                        if ((value - lastValue) > 1)
                                            return true;

                                        lastValue = value;

                                        return false;
                                    }); 
        }
    }

    return broken;
}

Report Last Valid Number Before The Break

This is useful in situations where one needs to report where the break happens, say the user is editing in a grid and one highlights the existing number which precedes the missing number(s).

Example here returns a 2 and 5 which are the numbers which precede the break.

   (new List() { 1, 2, 4, 5, 7, 8}).SequenceReportMissingsBreakStarts()

Here is the method:

public static IEnumerable<int> SequenceReportMissingsBreakStarts(this IList<int> sequence)
{

    var breaks = new List<int>();

    if ((sequence != null) && (sequence.Any()))
    {

        sequence.Aggregate((seed, aggr) =>
                            {
                                var diff = (aggr - seed) - 1;

                                if (diff > 0)
                                    breaks.Add(seed);
                                return aggr;
                            });
    }

    return breaks;
}

Full Extension Source With Comments

Here is the code for an easier copy

public static class SequenceExtensions
{
    /// <summary>
    /// Take a sequence of numbers and if there are any gaps greater than 1 between the numbers,
    /// report true.
    /// </summary>
    /// <param name="sequence">A set of numbers to check.</param>
    /// <returns>True if the there is a break in the sequence of numbers.</returns>
    public static bool IsSequenceBroken(this IEnumerable<int> sequence)
    {
        bool broken = false;

        if (sequence != null)
        {
            var sequenceAsList = sequence.ToList();

            if (sequenceAsList.Any())
            {
                int lastValue = sequence.First();

                broken = sequence.Any(value =>
                                        {
                                            if ((value - lastValue) > 1)
                                                return true;

                                            lastValue = value;

                                            return false;
                                        });
            }
        }

        return broken;
    }

    /// <summary>
    /// Take a sequence of numbers and report the missing numbers. Stop at first break found.
    /// </summary>
    /// <param name="sequence">Set of Numbers</param>
    /// <returns>True of sequence has missing numbers</returns>
    public static IEnumerable<int> SequenceFindMissings(this IList<int> sequence)
    {

        var missing = new List<int>();

        if ((sequence != null) && (sequence.Any()))
        {
            sequence.Aggregate((seed, aggr) =>
                                {
                                    var diff = (aggr - seed) - 1;

                                    if (diff > 0)
                                        missing.AddRange(Enumerable.Range((aggr - diff), diff));

                                    return aggr;
                                });
        }

        return missing;

    }

    /// <summary>
    /// A missing break start in a sequence is where the drop off occurs in the sequence.
    /// For example 3, 5, has a missing break start of the #3 for #4 is the missing.
    /// </summary>
    /// <param name="sequence">Set of Numbers</param>
    /// <returns>The list of break numbers which exist before the missing numbers.</returns>
    public static IEnumerable<int> SequenceReportMissingsBreakStarts(this IList<int> sequence)
    {

        var breaks = new List<int>();

        if ((sequence != null) && (sequence.Any()))
        {

            sequence.Aggregate((seed, aggr) =>
                                {
                                    var diff = (aggr - seed) - 1;

                                    if (diff > 0)
                                        breaks.Add(seed);
                                    return aggr;
                                });
        }

        return breaks;

    }
}

Hope this helps!

Update 11.07.2013 : Added ICommanding example.
Update 10.25.2013 : Added how to use the CallerMemberName attribute with INotifyPropertyChanged in .Net 4.

This Post describes an MVVM roll your own implementation which provides a basic example of the MVVM and binding.

Create The VM

The view model (VM) implements the INotifyPropertyChange process to report any changes to any bound controls.

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Linq;
using System.Runtime.CompilerServices;
using System.Text;
using System.Threading.Tasks;

namespace SO_WPF.ViewModels {

public class MainVM : INotifyPropertyChanged 
{

    private List<string> _Members;
    private int _MemberCount;
    private bool _IsMembershipAtMax;
    public bool IsMembershipAtMax 
    {
        get { return MemberCount > 3; }
    }
    public int MemberCount 
    { 
        get { return _MemberCount; }
        set
        {
            _MemberCount = value; 
            OnPropertyChanged();
            OnPropertyChanged("IsMembershipAtMax");
        } 
    }

    public List<string> Members 
    { 
        get { return _Members; }
        set { _Members = value; OnPropertyChanged(); } 
    }
    public MainVM()
    {
        // Simulate Asychronous access, such as to a db.

        Task.Run(() =>
                    {
                        Members = new List<string>() {"Alpha", "Beta", "Gamma", "Omega"};
                        MemberCount = Members.Count;
                    });
    }
    /// <summary>Event raised when a property changes.</summary>
    public event PropertyChangedEventHandler PropertyChanged;

    /// <summary>Raises the PropertyChanged event.</summary>
    /// <param name="propertyName">The name of the property that has changed.</param>
    protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)
    {
        PropertyChangedEventHandler handler = PropertyChanged;
        if (handler != null)
        {
            handler(this, new PropertyChangedEventArgs(propertyName));
        }
    }

}
}

Main Page Code Behind

We now need to hook up the main page view model to the main page. To do that we will do two things, one, make a non INotifyPropertyChanged property on the class which will hold our view model. Two we will instantiate it, hook it up to the page’s data along with our property. Doing that ensures that everything on our page will get access to our view model, thanks to the data context and how controls inherit their parents data context.

using SO_WPF.ViewModels;

namespace SO_WPF
{
    public partial class MainWindow : Window
    {

        public MainVM ViewModel { get; set; }

        public MainWindow()
        {
            InitializeComponent();

            // Set the windows data context so all controls can have it.
            DataContext = ViewModel = new MainVM();

        }

    }
}

Xaml

Now in the xaml we can simply bind to the View Models properties directly without any fuss.

<Window x:Class="SO_WPF.MainWindow"
        xmlns:viewModels="clr-namespace:SO_WPF.ViewModels"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:i="http://schemas.microsoft.com/expression/2010/interactivity"
        xmlns:ei="http://schemas.microsoft.com/expression/2010/interactions"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        mc:Ignorable="d"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        d:DataContext="{d:DesignInstance {x:Type viewModels:MainVM}}"
        Title="MainWindow"
        Height="300"
        Width="400">

<StackPanel Orientation="Vertical">
    <ListBox Name="lbData"
                ItemsSource="{Binding Members}"
                SelectionMode="Multiple"
                Margin="10" />

    <Button Height="30"
            Width="80"
            Margin="10"
            Content="Click Me" />
</StackPanel>

</Window>

In the above code we bind the Members to the listbox just by specifying the Members property name. As to the highlighted lines, I have added them as a debug design option. That lets Visual Studio and Blend know that our data context is our MainVM. That allows for the editor to present us with the options of data binding to the appropriate items, and not having it blank.

This has been a simple example, but a powerful one which can be used as a binding strategy for any WPF, Silverlight or Windows Phone Xaml based applications in C#.

Note though it is not shown, sometimes in styles one needs the element name to bind to, where the data context will fail due to the nature of the style binding, the above page we would bind to the page name as provided (“MainWindow”) and then the property name as usual!

Extra Credit ICommanding

I won’t go into much detail about commanding, but the gist is that the ViewModel is not directly responsible for actions which can happen due to the ICommanding process, but allow for binding operations to occur against those actions and those actions are performed elsewhere usually on a view.

Below is our view model with the commanding public variables which can be consumed by controls (or other classes which have access to the VM).

public class MainVM : INotifyPropertyChanged
{
    #region Variables
       #region Commanding Operations

    public ICommand ToggleEditing { get; set; }
    public ICommand ReportError   { get; set; }
    public ICommand CheckSequence { get; set; }

       #endregion
       #region Properties
    public string ErrorMessage { // the usual INotifyProperty as shown before }
       #endregion
    #endregion
}

Then on our main page which consumes the view model we then process those requests by creating methods to fulfill those operations. Note that the example below references properties on the VM which were not shown in the example,
but that is not important in this article. But one variable is shown and that is the error message. This allow anyone to push an error using the commanding to the viewmodel which is subsequently shown. That is a peek at the power of commanding right there to allow a dependency injection of setting an error variable to be done outside the VM but used by those which consume the VM!

public partial class MainWindow : Window
{

    public MainWindow()
    {
        InitializeComponent();

        // Set the windows data context so all controls can have it.
        DataContext = ViewModel = new MainVM();

        SetupCommanding();
    }

    private void SetupCommanding()
    {
        // Commanding using OperationCommand class
        ViewModel.ToggleEditing         = new OperationCommand((o) => ViewModel.IsEditing = !ViewModel.IsEditing);
        ViewModel.ReportError           = new OperationCommand((o) => ViewModel.ErrorMessage = (string)o);
        ViewModel.CheckSequence         = new OperationCommand(CheckSequences, CanExecute);

    }

     private void CheckSequences(object obj)
     {
        ...
     }

    private bool CanExecute(object obj)
    {
        return !ViewModel.UnsavedsExist;
    }
}

Finally the ICommanding class used.

public class OperationCommand : ICommand
{

    #region Variables

    Func<object, bool> canExecute;
    Action<object> executeAction;

    public event EventHandler CanExecuteChanged;

    #endregion

    #region Properties

    #endregion

    #region Construction/Initialization

    public OperationCommand(Action<object> executeAction)
        : this(executeAction, null)
    {
    }

    public OperationCommand(Action<object> executeAction, Func<object, bool> canExecute)
    {
        if (executeAction == null)
        {
            throw new ArgumentNullException("Execute Action was null for ICommanding Operation.");
        }
        this.executeAction = executeAction;
        this.canExecute = canExecute;
    }

    #endregion

    #region Methods

    public bool CanExecute(object parameter)
    {
        bool result = true;
        Func<object, bool> canExecuteHandler = this.canExecute;
        if (canExecuteHandler != null)
        {
            result = canExecuteHandler(parameter);
        }

        return result;
    }

    public void RaiseCanExecuteChanged()
    {
        EventHandler handler = this.CanExecuteChanged;
        if (handler != null)
        {
            handler(this, new EventArgs());
        }
    }

    public void Execute(object parameter)
    {
        this.executeAction(parameter);
    }

    #endregion

A user wanted to parse basic text. Here is a regex pattern which  breaks out the user text.

 

string @pattern = @"
(?:OS\s)                     # Match but don't capture (MDC) OS, used an an anchor
(?<Version>\d\.\d+)          # Version of OS
(?:;)                        # MDC ;
(?<Phone>[^;]+)              # Get phone name up to ;
(?:;)                        # MDC ;
(?<Type>[^;]+)               # Get phone type up to ;
(?:;)                        # MDC ;
(?<Major>\d\.\d+)            # Major version
(?:;)
(?<Minor>\d+)                # Minor Version
";

string data = 
@"Windows Phone Search (Windows Phone OS 7.10;Acer;Allegro;7.10;8860)
Windows Phone Search (Windows Phone OS 7.10;HTC;7 Mozart T8698;7.10;7713)
Windows Phone Search (Windows Phone OS 7.10;HTC;Radar C110e;7.10;7720)";

 // Ignore pattern white space allows us to comment the pattern, it is not a regex processing command
var phones = Regex.Matches(data, pattern, RegexOptions.IgnorePatternWhitespace)
                  .OfType<Match>()
                  .Select (mt => new 
                  {
                    Name = mt.Groups["Phone"].Value.ToString(),
                    Type = mt.Groups["Type"].Value.ToString(),
                    Version = string.Format( "{0}.{1}", mt.Groups["Major"].Value.ToString(),
                                                        mt.Groups["Minor"].Value.ToString())
                  }
                  );
                  
Console.WriteLine ("Phones Supported are:");            

phones.Select(ph => string.Format("{0} of type {1} version ({2})", ph.Name, ph.Type, ph.Version))
      .ToList()
      .ForEach(Console.WriteLine);
      
/* Output
Phones Supported are:
Acer of type Allegro version (7.10.8860)
HTC of type 7 Mozart T8698 version (7.10.7713)
HTC of type Radar C110e version (7.10.7720)
*/