Delete user from membership problem

Question

User-1767698477 posted

I'm displaying users in a gridview with a delete button. I'm using the new keyword to generate a new instance. Why do I get an Object reference not set to an instance of an object message?

Public Sub DeleteCommand(sender As Object, e As CommandEventArgs)
Dim username As String = (e.CommandArgument.ToString)
Dim mu As New SqlMembershipProvider 
mu.DeleteUser(username, True) <- Object reference not set to an instance of an object.
GridView1.Data

<asp:GridView ID="GridView1" runat="server" AllowPaging="True" AllowSorting="True"
        AutoGenerateColumns="False" DataKeyNames="UserId" DataSourceID="SqlDataSource1">
        <Columns>
            <asp:BoundField DataField="UserId" HeaderText="UserId" ReadOnly="True" SortExpression="UserId" />
            <asp:BoundField DataField="Email" HeaderText="Email" SortExpression="Email" />
            <asp:BoundField DataField="PasswordQuestion" HeaderText="PasswordQuestion" SortExpression="PasswordQuestion" />
            <asp:CheckBoxField DataField="IsApproved" HeaderText="IsApproved" SortExpression="IsApproved" />
            <asp:TemplateField HeaderText="UserName" SortExpression="UserName">
                <ItemTemplate>
                    <asp:Label ID="Label1" runat="server" Text='<%# Bind("UserName") %>'></asp:Label>
                </ItemTemplate>
                <EditItemTemplate>
                    <asp:TextBox ID="TextBox1" runat="server" Text='<%# Bind("UserName") %>'></asp:TextBox>
                </EditItemTemplate>
            </asp:TemplateField>
            <asp:TemplateField ShowHeader="False">
                <ItemTemplate>
                    <asp:LinkButton ID="LinkButton1" runat="server" OnCommand="Deletecommand" CommandName="Deleteuser"
                        Text="Delete user" CommandArgument='<%# Bind("Username") %>'></asp:LinkButton>
                </ItemTemplate>
            </asp:TemplateField>
        </Columns>
    </asp:GridView>

Answer 1

User753101303 posted

Hi,

AFAIK it is not supposed to be used directly and more likely it's because it's not initialized property. Instead use MemberShip.DeleteUser(username,True) as shown at:
https://docs.microsoft.com/en-us/dotnet/api/system.web.security.membership.deleteuser?view=netframework-4.8 (and scroll down to samples)

The idea is that the actual provider is configured in the web.config file and MemberShip.DeleteUser will forward this call to the configured provider. As a result you can use the exact same code regardless of which membership provider is used behind the scene.

Answer 2

User-1767698477 posted

I have resolved my issue:

Dim username As String = (e.CommandArgument.ToString)
Membership.DeleteUser(username, True)
GridView1.DataBind()