Binding ASP TreeView to custom DataSource

I tried to bind data from few tables in db to TreeView. Beleow is my solution. ASP TreeView can be bound only to XmlDataSource or SiteMapDataSource, so I had to build XmlDataSource dynamically. Listing 1. Function building XmlDataSource

public XmlDataSource GenerateDataSource(List<products1> custList)
        {
            XmlDataSource returnItems = new XmlDataSource();
            returnItems.EnableCaching = false;
            
            XDocument document = new XDocument();
            using (EntityDataModel edm = new EntityDataModel())
            {
                XElement customersRoot = new XElement("customers");
                foreach (products1 customer in custList)
                {
                    XElement custNode = new XElement("customer", new XAttribute("text", customer.fullname),
                        new XAttribute("value", customer.name));

                    var magazines = edm.prod.Where(p => p.name == customer.name)
                            .SelectMany(p => p.magz);
                    foreach (var magazine in magazines)
                    {
                        // Create Magazine node
                        XElement magazineNode = new XElement("magazine", new XAttribute("text", magazine.name),
                            new XAttribute("value", magazine.id));
                                                
                        var users = edm.prod.Where(p => p.id == mag.id).SelectMany(p => p.users);
                        foreach (var user in users)
                        {
                            // Create User node
                            XElement userNode = new XElement("user", new XAttribute("text", user.fullname),
                            new XAttribute("value", user.id));

                            magazineNode.Add(userNode);
                        }
                        custNode.Add(magazineNode);
                    }
                    customersRoot.Add(custNode);
                }
                document.Add(customersRoot);
                returnItems.Data = document.ToString();                
            }
            returnItems.XPath = "/*/*";
            return returnItems;
        }

Listing 2. Binding to control:

XmlDataSource xmlDataSource = GenerateDataSource(custList);
            TreeView1.DataSource = xmlDataSource;
            TreeView1.DataBind();

Listing 3. Setting control to read text and value properties from XmlDataSource.

<asp:TreeView ID="TreeView1" runat="server" ExpandDepth="1"
    ShowLines="True" >
    <DataBindings>
        <asp:TreeNodeBinding DataMember="customer" TextField="text" ValueField="value" SelectAction="None"/>
        <asp:TreeNodeBinding DataMember="magazine" TextField="text" ValueField="value" SelectAction="None"/>
        <asp:TreeNodeBinding DataMember="user" TextField="text" ValueField="value" SelectAction="None"/>
    </DataBindings>
</asp:TreeView>

WHERE IN clause in Linq To Entities

Recently I found nice solution to dynamically build Linq Expression with WHERE IN clause. Listing 1. Function

        static Expression<Func<TElement, bool>> BuildContainsExpression<TElement, TValue>(
                        Expression<Func<TElement, TValue>> valueSelector, IEnumerable<TValue> values)
        {
            if (null == valueSelector) { throw new ArgumentNullException("valueSelector"); }
            if (null == values) { throw new ArgumentNullException("values"); }
            ParameterExpression p = valueSelector.Parameters.Single();

            // p => valueSelector(p) == values[0] || valueSelector(p) == ...
            if (!values.Any())
            {
                return e => false;
            }
            var equals = values.Select(value => (Expression)Expression.Equal(valueSelector.Body, Expression.Constant(value, typeof(TValue))));
            var body = equals.Aggregate<Expression>((accumulate, equal) => Expression.Or(accumulate, equal));
            return Expression.Lambda<Func<TElement, bool>>(body, p);
        }

Listing 2. Calling BuildContainsExpression function:

List<string> senderList = new List<string>();
senderList.Add("Jacek");
senderList.Add("Krystian");

using (EntityDataModel edm = new EntityDataModel())
{
       var query = edm.senders.Where(e => e.StartDate > DateTime.Now);
       query = query.Where(BuildContainsExpression<PrListing, string>(e => e.sendernm, sendersList));
}

This builds SQL expression like this: Listing 3. SQL Example

SELECT * FROM senders WHERE (sendernm = 'Jacek' || sendernm = 'Krystian')