Observable Collections
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by frans eilering
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Classes

In this project we need several Classes. They must be included in the Internet part. To create a new Class, select the ObservableCollection.Web with a right mouse click and select "New Item".

 

Select "Class", give it a name and click "OK".

Below a new Class Contact.vb is created.

We need four Classes.

·       Contact.vb

·       Functions.vb

·       SQLHelper.vb

·       Config.vb

You need to create the Classes this way. Just adding a Class to the ObservableCollection.Web directory on your computer will show it but will not be recognized.

The SQLhelper.vb Class can be copied from the attached project. Copy this code and paste in into the SQLHelper.vb Class just created.

In the Contact.vb Class I will use just the name, address and City of a Contact. Further, each contact will have an ID named IDContact. The ID will be a GUI, an automatically created ID of 38 characters.

Code of Class Contact.vb

Imports System.Data.SqlClient
Imports System.Data
Imports System
Imports System.Web
Namespace demo
    Public Class Contact 
        Private _City As String 
        Private _Address As String 
        Private _Name As String 
        Private _IDContact As String 
        Public Sub New()  
            MyBase.New()
        End Sub
        Public Property City() As String 
            Get
                Return _City
            End Get
            Set(ByVal Value As String)
                If Value = "" Then
                    _City = Nothing
                Else
                    _City = Value
                End If
            End Set
        End Property
        Public Property Address() As String 
            Get
                Return _Address
            End Get
            Set(ByVal Value As String)
                If Value = "" Then
                    _Address = Nothing
                Else
                    _Address = Value
                End If
            End Set
        End Property
        Public Property Name() As String 
            Get
                Return _Name
            End Get
            Set(ByVal Value As String)
                If Value = "" Then
                    _Name = Nothing
                Else
                    _Name = Value
                End If
            End Set
        End Property
        Public Property IDContact() As String 
            Get
                Return _IDContact
            End Get
            Set(ByVal Value As String)
                If Value = "" Then
                    _IDContact = Nothing
                Else
                    _IDContact = Value
                End If
            End Set
        End Property
         Public Overloads Function GetsContactAll() As SqlDataReader 
            Dim arParms() As SqlParameter = New SqlParameter(0) {}
             Return SqlHelper.ExecuteReader(demo.Config.Connectionstring, 
Data.CommandType.StoredProcedure, "O_GetS_ContactMaster", arParms)
        End Function 
    End Class 
End Namespace

The code in the Functions.vb Class will not be used as a Class but as a module. It is easier to implement.

Suppose I need IDContact. What happens if IDContact is empty or Nothing? I need an empty string.

           Contact.IDContact = demo.Functions.NullSafeString(key)

will give it.

 

Code Class Funcions.vb

Namespace demo
    Public Module Functions
        Public Function NullSafeString(ByVal arg As ObjectOptional ByVal 
returnIfEmpty As String = ""As String
            Dim returnValue As String
            If (arg Is DBNull.Value) OrElse (arg Is NothingOrElse (arg Is 
String.Empty) Then
                returnValue = returnIfEmpty
            Else
                Try
                    returnValue = CStr(arg).Trim
                Catch
                    returnValue = returnIfEmpty
                End Try
            End If
            Return returnValue
        End Function
    End Module
End Namespace

Then the Config.vb Class. This is also a module. In the Contact Class I want to get data from the SQL database through a connection string.

demo.Config.Connectionstring

will give it.

Code Class Config.vb

Imports System.Web
Imports System.Configuration
Namespace demo
    Public Module Config
        Dim result As String
        Public Function Connectionstring() As String
            result = (ConfigurationManager.AppSettings("ConnectionItalie"))
            Return result
        End Function
    End Module
End Namespace

The connection information itself is stored in the config.web part.

Code for the Config.web.

<?xml version="1.0"?>
 
 
<configuration>
    <system.web>
        <compilation debug="true" strict="false" explicit="true" targetFramework="4.0" />
    </system.web>
    <appSettings>
        <add key="ConnectionItalie" 
value="Data Source='URL'; user ID='username';Password='Password';Initial 
Catalog='DatabaseName';" />
    </appSettings>
 
    <system.serviceModel>
        <behaviors>
            <serviceBehaviors>
                <behavior name="">
                    <serviceMetadata httpGetEnabled="true" />
                    <serviceDebug includeExceptionDetailInFaults="false" />
                </behavior>
            </serviceBehaviors>
        </behaviors>
        <serviceHostingEnvironment multipleSiteBindingsEnabled="true" />
    </system.serviceModel>
</configuration>

 


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User Comments

Title: C# Code example   
Name: eilering
Date: 2011-09-16 3:50:25 AM
Comment:
The VB code is very basic. If you copy the code and use a convertor like
http://converter.telerik.com/
then you can paste it and you get the C# code.

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