OracleConnectionStringBuilder.TryGetValue(String, Object) Método

Definición

Espacio de nombres:

System.Data.OracleClient

Ensamblado:

System.Data.OracleClient.dll

Recupera un valor que corresponde a la clave proporcionada por este OracleConnectionStringBuilder.

public:
 override bool TryGetValue(System::String ^ keyword, [Runtime::InteropServices::Out] System::Object ^ % value);

public override bool TryGetValue (string keyword, out object value);

override this.TryGetValue : string * obj -> bool

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

Parámetros

keyword

String

Clave del elemento que se va a recuperar.

value

Object

Valor que corresponde a keyword.

Devoluciones

Boolean

Es true si keyword fue encontrado dentro de la cadena de conexión, en caso contrario, es false.

Ejemplos

En el ejemplo siguiente se muestra el comportamiento del TryGetValue método .

// You may need to set a reference to the System.Data.OracleClient
// assembly before you can run this sample.
using System.Data.OracleClient;

class Program
{
    static void Main()
    {
        OracleConnectionStringBuilder builder = new OracleConnectionStringBuilder();
        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, null);

        Console.WriteLine("Press any key to continue.");
        Console.ReadLine();
    }

    private static void DisplayValue(OracleConnectionStringBuilder builder, string key)
    {
        object value = null;

        // Although TryGetValue handles missing keys,
        // it does not handle passing in a null
        // key. This example traps for that particular error, but
        // passes any other unknown exceptions back out to the
        // caller.
        try
        {
            if (builder.TryGetValue(key, out value))
            {
                Console.WriteLine("{0}='{1}'", key, value);
            }
            else
            {
                Console.WriteLine("Unable to retrieve value for '{0}'", key);
            }
        }
        catch (ArgumentNullException)
        {
            Console.WriteLine("Unable to retrieve value for null key.");
        }
    }

    private static string GetConnectionString()
    {
        // To avoid storing the connection string in your code,
        // you can retrieve it from a configuration file.
        return "Server=OracleDemo;Integrated Security=True";
    }
}

' You may need to set a reference to the System.Data.OracleClient
' assembly before you can run this sample.
Imports System.Data.OracleClient

Module Module1
    Sub Main()
        Dim builder As New OracleConnectionStringBuilder()
        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.")
        Console.ReadLine()
    End Sub

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

        ' Although TryGetValue handles missing keys just fine,
        ' 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

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

Comentarios

El TryGetValue método permite a los desarrolladores recuperar de forma segura un valor de un sin OracleConnectionStringBuilder necesidad de comprobar que el nombre de clave proporcionado es un nombre de clave válido. Dado que TryGetValue controla correctamente la búsqueda de una clave inexistente, no es necesario buscar la existencia de una clave antes de recuperar su valor. La llamada TryGetValue a con una clave inexistente colocará el valor null (Nothing en Visual Basic) en el value parámetro .

Consulte también

• Creación de cadenas de conexión