SqlRoleProvider.RoleExists(String) Method
Important
Some information relates to prerelease product that may be substantially modified before it’s released. Microsoft makes no warranties, express or implied, with respect to the information provided here.
Gets a value indicating whether the specified role name already exists in the role database.
public:
override bool RoleExists(System::String ^ roleName);
public override bool RoleExists (string roleName);
override this.RoleExists : string -> bool
Public Overrides Function RoleExists (roleName As String) As Boolean
- roleName
- String
The name of the role to search for in the database.
true
if the role name already exists in the database; otherwise, false
.
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.
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>
<%@ Page Language="VB" %>
<%@ 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">
Dim rolesArray() As String
Public Sub Page_Load(sender As Object, args As EventArgs)
If Not IsPostBack Then
' Bind roles to GridView.
rolesArray = Roles.GetAllRoles()
RolesGrid.DataSource = rolesArray
RolesGrid.DataBind()
End If
End Sub
Public Sub CreateRole_OnClick(sender As Object, args As EventArgs)
Dim createRole As String = RoleTextBox.Text
Try
If Roles.RoleExists(createRole) Then
Msg.Text = "Role '" & Server.HtmlEncode(createRole) & "' already exists. Please specify a different role name."
Return
End If
Roles.CreateRole(createRole)
Msg.Text = "Role '" & Server.HtmlEncode(createRole) & "' created."
' Re-bind roles to GridView.
rolesArray = Roles.GetAllRoles()
RolesGrid.DataSource = rolesArray
RolesGrid.DataBind()
Catch
Msg.Text = "Role '" & Server.HtmlEncode(createRole) & "' <u>not</u> created."
End Try
End Sub
</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>
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).
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 |
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