DbConnectionStringBuilder.TryGetValue Method (String, Object)


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

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

Public Overridable 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 the key.

Return Value

Type: System.Boolean

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

Exception Condition

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=,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)

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. 
        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

The sample displays the following results:

Unable to retrieve value for //InvalidKey//
Unable to retrieve value for null key.

Universal Windows Platform
Available since 10
.NET Framework
Available since 2.0
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