SqlConnectionStringBuilder.TryGetValue Method (String, Object)


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

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

Public Overrides Function TryGetValue (
	keyword As String,
	<OutAttribute> ByRef value As Object
) As Boolean


Type: System.String

The key of the item to retrieve.

Type: System.Object

The value corresponding to keyword.

Return Value

Type: System.Boolean

true if keyword was found within the connection string; otherwise, false.

Exception Condition

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

The TryGetValue method lets developers safely retrieve a value from a SqlConnectionStringBuilder without needing to verify that the supplied key name is a valid key name. 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 value null (Nothing in Visual Basic) in the value parameter.

The following example demonstrates the behavior of the TryGetValue method.

Imports System.Data.SqlClient

Module Module1
    Sub Main()
        Dim builder As New SqlConnectionStringBuilder
        builder.ConnectionString = GetConnectionString()

        ' Call TryGetValue method for multiple
        ' key names. Note that these keys are converted
        ' to well-known synonynms for data retrieval.
        DisplayValue(builder, "Data Source")
        DisplayValue(builder, "Trusted_Connection")
        DisplayValue(builder, "InvalidKey")
        DisplayValue(builder, Nothing)

        Console.WriteLine("Press any key to continue.")
    End Sub

    Private Sub DisplayValue( _
     ByVal builder As SqlConnectionStringBuilder, ByVal key As String)
        Dim value As Object = Nothing

        ' 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
        ' passes any other unknown exceptions back out to the
        ' caller. 
            If builder.TryGetValue(key, value) Then
                Console.WriteLine("{0}='{1}' ", key, value)
                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

    Private Function GetConnectionString() As String
        ' To avoid storing the connection string in your code,
        ' you can retrieve it from a configuration file. 
        Return "Server=(local);Integrated Security=SSPI;" & _
          "Initial Catalog=AdventureWorks"
    End Function
End Module

The sample displays the following results:

Data Source=(local)
Unable to retrieve value for 'InvalidKey'
Unable to retrieve value for null key.

.NET Framework
Available since 2.0
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