Question

Say I have a LINQ-to-XML query that generates an anonymous type like this:

var aQuery =
               (from a in document.Root.Elements("items")
                select new {
                    id = a.Attribute("id").Value,
                    type = a.Attribute("type").Value,
                    modified = a.Attribute("modified").Value
                });

if there a way to store that query expression in a variable or constant and then execute at runtime? The basic idea is that I have a bunch of these expressions and it would be handy if they could all be defined in one place and then invoked dynamically thru a single method where I just need to pass in the XML document and which expression to use. Thanks.

Answer 1

You could define them as methods quite easily, though you’d forfit the right to use anonymous types.

public static IQueryable<Item> GetItemsFromXml(XDocument document)
{
    return (from a in document.Root.Elements("items") 
            select new Item 
            {
                Id = a.Attribute("id").Value, 
                Type = a.Attribute("type").Value, 
                Modified = a.Attribute("modified").Value 
            }); 
}

Having said that, patterns like the repository pattern are used to wrap the whole process of accessing data.