SqlConnectionStringBuilder.TryGetValue(String, Object) Método

Definición

Espacio de nombres:
System.Data.SqlClient
Ensamblado:
System.Data.dll

Recupera un valor correspondiente a la clave proporcionada de este SqlConnectionStringBuilder.

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 correspondiente a keyword.

Devoluciones

Boolean

true si se encontró keyword en el cadena de conexión; de lo contrario, false.

Excepciones

ArgumentNullException

keyword contiene un valor NULL (Nothing en Visual Basic).

Ejemplos

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

using System.Data.SqlClient;

using System;
using System.Data.SqlClient;

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

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

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

        // Although TryGetValue handles missing keys,
        // it doesn't 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=(local);Integrated Security=SSPI;" +
            "Initial Catalog=AdventureWorks";
    }
}

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.")
        Console.ReadLine()
    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. 
        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=(local);Integrated Security=SSPI;" & _
          "Initial Catalog=AdventureWorks"
    End Function
End Module

En el ejemplo se muestran los siguientes resultados:

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

Comentarios

El TryGetValue método permite a los desarrolladores recuperar de forma segura un valor de un SqlConnectionStringBuilder sin necesidad de comprobar que el nombre de clave proporcionado es un nombre de clave válido. Dado que TryGetValue no genera una excepción al llamarlo, pasar una clave inexistente, no tiene que buscar una clave antes de recuperar su valor. Al llamar a TryGetValue con una clave inexistente, el valor null (Nothing en Visual Basic) en el parámetro value.

Se aplica a

Consulte también