asp.net - Bind to a linq datasource and add external column

Question

I have a databound control which displays a grid. The grid is bound to a linq to sql data source. I use the following code:

PaymentsDataContext data = new PaymentsDataContext();
            var q = from act in data.activations
                    where act.approved != true
                    orderby act.activationDate ascending
                    select new {activationID = act.activationID, userName = act.userName,
                    brokerName = act.broker.brokerName, existingAccount = act.existingAccount,
                    activationDate = act.activationDate, brokerUser = act.brokerUser, approved = act.approved};
            activationPending.DataSource = q;
            activationPending.DataBind();

I want to add another column to the grid. I want to show the user's email address. I get it like so:

var member = System.Web.Security.Membership.GetUser(username);
string email = member.Email;

How could I add this as a field in the grid, since it's not in the Payment DB at all?

What grid component are you using? Some have the ability to add calculated columns without they're being in the bound data source. — Yuck, Jul 21 '11 at 01:29

score 2 · Accepted Answer · edited Jul 21 '11 at 02:16

try this:

var q = from act in data.activations
                    where act.approved != true
                    orderby act.activationDate ascending
                    select new {activationID = act.activationID, userName = act.userName,
                    brokerName = act.broker.brokerName, 
                    existingAccount = act.existingAccount,
                    activationDate = act.activationDate, brokerUser = act.brokerUser,
                    approved = act.approved, 
                    email = System.Web.Security.Membership.GetUser(act.userName).Email };

since you already bin q and not data.activations this adds the external column to the grid.

Edit : Because of the new added column your template of the grid view must have a place to accept it you can add this manually like :

<asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="true">
<Columns>
.
.
<asp:BoundField DataField="email" HeaderText="email" 
            SortExpression="email" />
.
.
</Columns>
 </asp:GridView>

or set the property of the gridview named AutoGenerateColumns to true

<asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="true">
    </asp:GridView>

I hoped you were right, but no. I get a null object ref exception. — Elad Lachmi, Jul 21 '11 at 01:37
If act.userName is not guranteed to return an eMail-Adress via GetUser then this can happen... I need to think a bit about this... — Yahia, Jul 21 '11 at 01:40
It is guranteed. Both username and email address are 'Not NULL' in both the DB itself and the DAL. Even if that statment was not really true, I checked the current table and every user has an email address. — Elad Lachmi, Jul 21 '11 at 01:45

score 0 · Answer 2 · edited May 23 '17 at 12:11

you can write the Extension method and use it in your select. Check this topic

 private Func<DataClasses.Activations, String> GetUserEmail(string username)
 {
    return System.Web.Security.Membership.GetUser(username).Email;
 }

 PaymentsDataContext data = new PaymentsDataContext();
        var q = from act in data.activations
                where act.approved != true
                orderby act.activationDate ascending
                select new {activationID = act.activationID, userName = act.userName,
                brokerName = act.broker.brokerName, existingAccount = act.existingAccount,
                activationDate = act.activationDate, brokerUser = act.brokerUser, approved = act.approved, 
                Email = GetUserEmail(act.username)};

This might work, but I must say I'm in over my head with that thread. I don't know linq that well and I have no idea what they are going on about. Any chance you can point me to a specific answer or part of an answer. — Elad Lachmi, Jul 21 '11 at 01:47

asp.net - Bind to a linq datasource and add external column

2 Answers2