RoleProvider.RoleExists Method
Gets a value indicating whether the specified role name already exists in the role data source for the configured applicationName.
Assembly: System.Web (in System.Web.dll)
'Declaration Public MustOverride Function RoleExists ( _ roleName As String _ ) As Boolean 'Usage Dim instance As RoleProvider Dim roleName As String Dim returnValue As Boolean returnValue = instance.RoleExists(roleName)
Parameters
- roleName
- Type: System.String
The name of the role to search for in the data source.
Return Value
Type: System.Booleantrue if the role name already exists in the data source for the configured applicationName; otherwise, false.
RoleExists is called by the RoleExists method of the Roles class to determine whether a role name exists in the data source for the configured ApplicationName.
If the specified role name is Nothing or is an empty string, we recommend that your provider throw an exception.
The following code example shows a sample implementation of the RoleExists method.
Public Overrides Function RoleExists(ByVal rolename As String) As Boolean If rolename Is Nothing OrElse rolename = "" Then _ Throw New ProviderException("Role name cannot be empty or null.") Dim exists As Boolean = False Dim conn As OdbcConnection = New OdbcConnection(connectionString) Dim cmd As OdbcCommand = New OdbcCommand("SELECT COUNT(*) FROM Roles " & _ " WHERE Rolename = ? AND ApplicationName = ?", conn) cmd.Parameters.Add("@Rolename", OdbcType.VarChar, 255).Value = rolename cmd.Parameters.Add("@ApplicationName", OdbcType.VarChar, 255).Value = ApplicationName Try conn.Open() Dim numRecs As Integer = CType(cmd.ExecuteScalar(), Integer) If numRecs > 0 Then exists = True End If Catch e As OdbcException ' Handle exception. Finally conn.Close() End Try Return exists End Function
Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98
The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.