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DbConnectionStringBuilder.TryGetValue Method

Retrieves a value corresponding to the supplied key from this DbConnectionStringBuilder.

Namespace:  System.Data.Common
Assembly:  System.Data (in System.Data.dll)

'Declaration
Public Overridable Function TryGetValue ( _
	keyword As String, _
	<OutAttribute> ByRef value As Object _
) As Boolean
'Usage
Dim instance As DbConnectionStringBuilder 
Dim keyword As String 
Dim value As Object 
Dim returnValue As Boolean 

returnValue = instance.TryGetValue(keyword, _
	value)

Parameters

keyword
Type: System.String

The key of the item to retrieve.

value
Type: System.Object%

The value corresponding to the key.

Return Value

Type: System.Boolean
true if keyword was found within the connection string, false otherwise.

ExceptionCondition
ArgumentNullException

keyword contains a null value (Nothing in Visual Basic).

The TryGetValue method lets developers safely retrieve a value from a DbConnectionStringBuilder without needing to first call the ContainsKey method. Because TryGetValue does not raise an exception when you call it, passing in a nonexistent key, you do not have to look for a key before retrieving its value. Calling TryGetValue with a nonexistent key will place the null value (Nothing in Visual Basic) in the value parameter.

The following example calls the TryGetValue method, demonstrating several possible outcomes.

Sub Main()
    Dim builder As New DbConnectionStringBuilder
    builder.ConnectionString = _
        "Provider=sqloledb;Data Source=192.168.168.1,1433;" & _
        "Network Library=DBMSSOCN;Initial Catalog=pubs;" & _
        "Integrated Security=SSPI;" 

    ' Call TryGetValue method for multiple 
    ' key names.
    DisplayValue(builder, "Provider")
    DisplayValue(builder, "DATA SOURCE")
    DisplayValue(builder, "InvalidKey")
    DisplayValue(builder, Nothing)

    Console.ReadLine()
End Sub 

Private Sub DisplayValue( _
 ByVal builder As DbConnectionStringBuilder, ByVal key As String)
    Dim value As Object

    ' Although TryGetValue handles missing keys, 
    ' it doesn't handle passing in a null (Nothing in Visual Basic) 
    ' key. This example traps for that particular error, but 
    ' bubbles any other unknown exceptions back out to the 
    ' caller.  
    Try 
        If builder.TryGetValue(key, value) Then
            Console.WriteLine("{0}={1}", key, value)
        Else
            Console.WriteLine("Unable to retrieve value for '{0}'", key)
        End If 
    Catch ex As ArgumentNullException
        Console.WriteLine("Unable to retrieve value for null key.")
    End Try 
End Sub

The sample displays the following results:

Provider=sqloledb
DATA SOURCE=192.168.168.1,1433
Unable to retrieve value for //InvalidKey//
Unable to retrieve value for null key.

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

.NET Framework

Supported in: 3.5, 3.0, 2.0

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