A Programmer with Microsoft tools

Sometimes it’s difficult

I am a good contributor(+moderator) at www.asp.net forums ( and I love MVC ). Sometimes it’s very difficult to stay calm . Let’s make an example:

[new programmer first post]

Hi I am new in ASP.NET mvc 3

I want to insert/modify collection on the page without refresh.

[ code for database first]

Now on create product View I want to add a composite in IList<Composite> Composites collection.

[My answer]

2 things here:
Modify a collection in MVC : http://haacked.com/archive/2008/10/23/model-binding-to-a-list.aspx

Send via ajax : http://bit.ly/mvc_ajax_jquery

[new programmer answer after 4 ( FOUR!) minutes]

Hi ignatandrei

Thanks for the reply.

But I have no idea how to implement this thing.

can you give me a small example regarding this.

I have tried many times but not successed.

[My answer]

quoting “I have no idea how to implement this thing” from new programmer

What thing of the 2 I have shown you ?
More, I admire your fast reading if you read 2 tutorials(max 6 minutes) so fast , download codes , reproduce and decide that you do not understand.

[new programmer]

Hello ignatandrei

I am sorry… The links which you have posted was not underlined/highlighted; so that’s why I thought it were like suggentions. because of that misunderstanding I replied you back for demo application.

And then the usual combination of “ I am getting an error” – although my tutorial it handles errors – both from server side and communication side

However, when someone asks for help it is good to READ what other said – even it was suggestions…

And , as I say, sometimes it is difficult to stay calm. What have you answered?

Sample Kinect application

Made my first application for Kinect. It was just a combination of multiple other source code + EF4.3 for SqlServer Compact 4.0 ( to can have a database without pain of installing).

As learning:

The audio recognition does not work very well.
It was fun to write
Do not make an action for each joint movement – it is overwhelming for Kinect
If you approach Kinect device perpendicular ( such as line of shoulders is perpendicular to Kinect) it does not recognize you.

The application makes a simple thing:

You can use them to photo the thiefs that comes after you left the house.
Just press “Capture” (or make a circle with the right hand) and after a timeout( set in option) the application will register, via Kinect, any new human move.It will save to the
<user profile> AppData\Roaming\Pictures and, if configured , to a website ( more details later this month).

Download from here if you have a Kinect device

https://kinectantitheft.codeplex.com/

friday links 24

MVP 2012 C#

https://mvp.support.microsoft.com/profile/Andrei.Ignat

April 2, 2012
3 Comments
Andrei Ignat
mvp

friday links 23

First WPF application – simple login

I am trying to make an application with WPF( I do not have done this experiment before – windows forms were too easy).

First attempt is to create a control for userlogin – a user can have name, password, and – if registers – email.

All is done declaratively – but what effort! Let’s see:

<Window x:Class="KinectAntiTheft.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:sys="clr-namespace:System;assembly=mscorlib"
        xmlns:local="clr-namespace:KinectAntiTheft_BL;assembly=KinectAntiTheft_BL"
        xmlns:ka="clr-namespace:KinectAntiTheft"
        Title="MainWindow" Height="350" Width="525" >
<Window.DataContext>
        <local:LoginViewModel />
    </Window.DataContext>
    <Window.Resources>
        <Style x:Key="errStyleLabel" TargetType="Label">
            <Setter Property="Background" Value="Red" />
            <Setter Property="FontStyle" Value="Italic" />
        </Style>
        <BooleanToVisibilityConverter x:Key="boolToVisibilityConverter" />
        <ObjectDataProvider MethodName="GetValues" ObjectType="{x:Type sys:Enum}" x:Key="UserRegMode">

            <ObjectDataProvider.MethodParameters>

                <x:Type TypeName="local:Mode" />

            </ObjectDataProvider.MethodParameters>

        </ObjectDataProvider>

    </Window.Resources>
    <Grid Name="MainGrid" Margin="2" >
        <Grid.RowDefinitions>
            <RowDefinition Height="37*" />
            <RowDefinition Height="82*" />
            <RowDefinition Height="63*" />
            <RowDefinition Height="58*" />
            <RowDefinition Height="67*" />
        </Grid.RowDefinitions>
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="92*" />
            <ColumnDefinition Width="407*"/>
        </Grid.ColumnDefinitions>
        <Label Content="UserName" Grid.Row="1" Height="28" HorizontalAlignment="Left" Margin="12,15,0,0" Name="lblUserName" VerticalAlignment="Top" />
        <TextBox Grid.Column="1" Grid.Row="1" Height="23" HorizontalAlignment="Left" Margin="32,20,0,0" Name="txtUserName" VerticalAlignment="Top" Width="339"
                 Text="{Binding Path=User.UserName, Mode=TwoWay, ValidatesOnDataErrors=True,UpdateSourceTrigger=PropertyChanged}"
                 />
        <Label Content="Password" Height="28" HorizontalAlignment="Left" Margin="12,12,0,0" Name="lblPassword" VerticalAlignment="Top" Grid.Row="2" />

        <PasswordBox Height="23" HorizontalAlignment="Left" Margin="32,26,0,0" Name="txtPassword" VerticalAlignment="Top" Width="339" Grid.Column="1" Grid.Row="2"
                 ka:PasswordBoxAssistant.BindPassword="True"
                ka:PasswordBoxAssistant.BoundPassword="{Binding Path=User.UserPassword, Mode=TwoWay, ValidatesOnDataErrors=True,UpdateSourceTrigger=PropertyChanged}"
                 />
        <Button Content="Login" Grid.Column="1" Grid.Row="4" Height="23" HorizontalAlignment="Left" Margin="32,32,0,0" Name="btnLogin" VerticalAlignment="Top" Width="75" CommandParameter="{Binding Path=User}" Command ="{Binding Path=LoginCommand, UpdateSourceTrigger=PropertyChanged}"/>
        <Label Grid.Column="1" Height="23" HorizontalAlignment="Left" Margin="32,5,0,0" Name="lblError" Content="{ Binding Path=Error, Mode=TwoWay}" VerticalAlignment="Top" Width="200" Style="{StaticResource errStyleLabel}" Visibility="{Binding Path=IsError, Converter={StaticResource boolToVisibilityConverter}}" />
        <ComboBox Height="23" HorizontalAlignment="Left" Margin="5,5,0,0" Name="cmbMode" VerticalAlignment="Top" Width="72"
                  ItemsSource="{Binding Source={StaticResource UserRegMode }}"   SelectedValue="{Binding Path=User.ModeUser}" />
        <Label Content="Email" Height="28" HorizontalAlignment="Left" Margin="17,22,0,0" Name="lblEmail" VerticalAlignment="Top" Grid.Row="3" Visibility="{Binding Path=User.IsRegister, Converter={StaticResource boolToVisibilityConverter}}" />
        <TextBox Height="23" HorizontalAlignment="Left" Margin="32,22,0,0" Name="txtEmail" Text="{Binding Path=User.UserEmail, Mode=TwoWay, ValidatesOnDataErrors=True, UpdateSourceTrigger=PropertyChanged}" VerticalAlignment="Top" Width="339" Grid.Column="1" Grid.Row="3" Visibility="{Binding Path=User.IsRegister, Converter={StaticResource boolToVisibilityConverter}}" />
    </Grid>
</Window>

I will point just several ideas:

If the data comes from other assembly, just put xmlns:local="clr-namespace:<other namespace>;assembly=<other assembly>"
If you want to make visible/invisible a controle, it is not enough to put visible * you must also use a converter
```
Visibility="{Binding Path=IsError, Converter={StaticResource boolToVisibilityConverter}}"
```
Use DelegateCommands from Prism . http://compositewpf.codeplex.com/
PasswordBox can not have it’s Password property binded. You can either transfer all textbox, or break security and add attached property
You can have enum binded to a combobox and, more, translate into resources
Do not forget to raise property changed ! – it is a PIA – but, hey, it is fun on GUI

Final Conclusion: WPF is a mature technology – and there are enough resources on the internet to learn well.

S0lution for a sample login/register form you will find here :login wpf

March 26, 2012
3 Comments
Andrei Ignat
wpf

friday links 22

IValidatableObject and IDataErrorInfo

At the beginning it was IDataErrorInfo. Next , it came IValidatableObject. And , because some GUI frameworks implement one and not other, I must think to a common way to validate once .

My choice was to validate with IValidatableObject and IDataErrorInfo just re-send data.

I made an example with a class User which has UserName, UserEmail and UserPassword.

Without much ado, this is the code:

 public class User : IValidatableObject, IDataErrorInfo
    {
        public string UserEmail { get; set; }
        public string UserName { get; set; }
        public string UserPassword { get; set; }

        public IEnumerable<ValidationResult> Validate(ValidationContext validationContext)
        {
            if (string.IsNullOrEmpty(UserEmail))
                yield return new ValidationResult("UserName", new string[1] { "UserName" });

            if (string.IsNullOrEmpty(UserEmail))
                yield return new ValidationResult("UserEmail", new string[1] { "UserEmail" });

            if (string.IsNullOrEmpty(UserEmail))
                yield return new ValidationResult("UserPassword", new string[1] { "UserPassword" });

            
        }

        //IDataErrorInfo - you can copy this code to each class
        public string Error
        {
            get { return this[""]; }
        }

        public string this[string columnName]
        {
            get
            {
                string ret = null;
                var data = this.Validate(new ValidationContext(this, null, null));
                switch (columnName)
                {
                    case "":

                        foreach (var item in data)
                        {
                            ret += item.ErrorMessage + Environment.NewLine;
                        }
                        break;
                    default:
                        foreach (var item in data)
                        {
                            if (item.MemberNames.Contains(columnName))
                                ret += item.ErrorMessage + Environment.NewLine;
                        }
                        break;
                }
                return ret;
            }
        }
    }

And you can verify like this:

User u = new User();
            
            Console.WriteLine("-----from  IDataErrorInfo");
            string err = (u as IDataErrorInfo)[""];
            Console.WriteLine(err);
            
            Console.WriteLine("-----from  IvalidatableObject");
            foreach(var item in (u as IValidatableObject).Validate(new ValidationContext(u, null, null)))
            {
                Console.WriteLine(item.MemberNames.First());
            }


            Console.WriteLine("-----from  Validator");
            try
            {
                Validator.ValidateObject(u, new ValidationContext(u, null, null), true);
            }
            catch (ValidationException EX)
            {

                Console.WriteLine("JUST " + EX.Message);
            }

You can find the code also there
Validation