RoleProvider.RoleExists Method
.NET Framework 2.0
Gets a value indicating whether the specified role name already exists in the role data source for the configured applicationName.
Namespace: System.Web.Security
Assembly: System.Web (in system.web.dll)
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)
public abstract boolean RoleExists ( String roleName )
public abstract function RoleExists ( roleName : String ) : boolean
Not applicable.
Parameters
- roleName
The name of the role to search for in the data source.
Return Value
true 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 roleName is a null reference (Nothing in Visual Basic) 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
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