RoleProvider.RoleExists Method (String)

 

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.ApplicationServices (in System.Web.ApplicationServices.dll)

Public MustOverride Function RoleExists (
	roleName As String
) As Boolean

Parameters

roleName
Type: System.String

The name of the role to search for in the data source.

Return Value

Type: System.Boolean

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 role name is null 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

.NET Framework
Available since 2.0
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