Roles.RoleExists(String) Method
Definition
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 data source.
public:
static bool RoleExists(System::String ^ roleName);
public static bool RoleExists (string roleName);
static member RoleExists : string -> bool
Public Shared Function RoleExists (roleName As String) As Boolean
Parameters
- roleName
- String
The name of the role to search for in the data source.
Returns
true
if the role name already exists in the data source; otherwise, false
.
Exceptions
roleName
is null
(Nothing
in Visual Basic).
roleName
is an empty string or contains a comma (,).
Role management is not enabled.
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 Roles.
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>
Remarks
The RoleExists method calls the RoleExists
method of the default role provider to determine whether a role name exists in the data source for the application that is specified in the ApplicationName property.
Applies to
See also
משוב
https://aka.ms/ContentUserFeedback.
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