SqlConnectionStringBuilder.TryGetValue(String, Object) Method
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Retrieves a value corresponding to the supplied key from this 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
- keyword
- String
The key of the item to retrieve.
- value
- Object
The value corresponding to keyword
.
true
if keyword
was found within the connection string; otherwise, false
.
keyword
contains a null value (Nothing
in Visual Basic).
The following example demonstrates the behavior of the TryGetValue method.
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
The sample displays the following results:
Data Source=(local)
Trusted_Connection=True
Unable to retrieve value for 'InvalidKey'
Unable to retrieve value for null key.
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.
Produkt | Versions |
---|---|
.NET | Core 1.0, Core 1.1, 6 (package-provided), 8 (package-provided) |
.NET Framework | 2.0, 3.0, 3.5, 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7 (package-provided), 4.7, 4.7.1 (package-provided), 4.7.1, 4.7.2 (package-provided), 4.7.2, 4.8 (package-provided), 4.8, 4.8.1 |
.NET Standard | 2.0 (package-provided) |
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