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RoleExists Method

RoleProvider.RoleExists Method

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)

public abstract bool RoleExists (
	string 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 override bool RoleExists(string rolename)
{
  if (rolename == null || rolename == "")
    throw new ProviderException("Role name cannot be empty or null.");

  bool exists = false;

  OdbcConnection conn = new OdbcConnection(connectionString);
  OdbcCommand cmd = 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();

    int numRecs = (int)cmd.ExecuteScalar();

    if (numRecs > 0)
    {
      exists = true;
    }
  }
  catch (OdbcException)
  {
    // Handle exception.
  }
  finally
  {
    conn.Close();      
  }

  return exists;
}

Windows 98, Windows Server 2000 SP4, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.

.NET Framework

Supported in: 3.0, 2.0

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