RoleProvider.RoleExists Method
.NET Framework 3.0
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)
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; }
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