SqlRoleProvider.RoleExists(String) Method

Definition

Gets a value indicating whether the specified role name already exists in the role database.

public override bool RoleExists (string roleName);

Parameters

roleName
String

The name of the role to search for in the database.

Returns

true if the role name already exists in the database; otherwise, false.

Exceptions

roleName is null.

roleName is an empty string or contains a comma.

-or-

roleName is longer than 256 characters.

An unknown error occurred while communicating with the database.

Examples

The following code example uses the RoleExists method to determine whether a role name already exists before creating the role. For an example of a Web.config file that enables role management, see SqlRoleProvider.

Important

This example contains a text box that accepts user input, which is a potential security threat. By default, ASP.NET Web pages validate that user input does not include script or HTML elements. For more information, see Script Exploits Overview.

<%@ Page Language="C#" %>
<%@ Import Namespace="System.Web.Security" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">

string[] rolesArray;

public void Page_Load(object sender, EventArgs args)
{
  if (!IsPostBack)
  {
    // Bind roles to GridView.

    rolesArray = Roles.GetAllRoles();
    RolesGrid.DataSource = rolesArray;
    RolesGrid.DataBind();
  }
}

public void CreateRole_OnClick(object sender, EventArgs args)
{
  string createRole = RoleTextBox.Text;

  try
  {
    if (Roles.RoleExists(createRole))
    {
      Msg.Text = "Role '" + Server.HtmlEncode(createRole) + "' already exists. Please specify a different role name.";
      return;
    }

    Roles.CreateRole(createRole);

    Msg.Text = "Role '" + Server.HtmlEncode(createRole) + "' created.";

    // Re-bind roles to GridView.

    rolesArray = Roles.GetAllRoles();
    RolesGrid.DataSource = rolesArray;
    RolesGrid.DataBind();
  }
  catch (Exception e)
  {
    Msg.Text = "Role '" + Server.HtmlEncode(createRole) + "' <u>not</u> created.";
    Response.Write(e.ToString());
  }

}

</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head>
<title>Sample: Create Role</title>
</head>
<body>

<form runat="server" id="PageForm">
  <h3>Create a Role</h3>

  <asp:Label id="Msg" ForeColor="maroon" runat="server" /><br />

  Role name: 

  <asp:TextBox id="RoleTextBox" runat="server" />

  <asp:Button Text="Create Role" id="CreateRoleButton"
              runat="server" OnClick="CreateRole_OnClick" />

  <br />

  <asp:GridView runat="server" CellPadding="2" id="RolesGrid" 
                Gridlines="Both" CellSpacing="2" AutoGenerateColumns="false" >
    <HeaderStyle BackColor="navy" ForeColor="white" />
    <Columns>
      <asp:TemplateField HeaderText="Roles" >
        <ItemTemplate>
          <%# Container.DataItem.ToString() %>
        </ItemTemplate>
      </asp:TemplateField>
    </Columns>
   </asp:GridView>
</form>

</body>
</html>

Remarks

The RoleExists method is called by the Roles class to determine whether a role name exists in the SQL Server database specified in the ASP.NET application's configuration file (Web.config).

Applies to

Product Versions
.NET Framework 2.0, 3.0, 3.5, 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8, 4.8.1

See also