Since we’ll be re-using this collection of cities in several
other samples, I decided to encapsulate my travels in a “TravelOrganizer” class
like so:
Listing 10
using System;
using System.Collections.Generic;
public class TravelOrganizer
{
public List<Location> PlacesVisited
{
get
{
List<Location> cities = new List<Location>{
new
Location { City="London", Distance=4789, Country="UK" },
new
Location { City="Amsterdam", Distance=4869, Country="Netherlands" },
new
Location { City="San Francisco", Distance=684, Country="USA" },
new
Location { City="Las Vegas", Distance=872, Country="USA" },
new
Location { City="Boston", Distance=2488, Country="USA" },
new Location
{ City="Raleigh", Distance=2363, Country="USA" },
new
Location { City="Chicago", Distance=1733, Country="USA" },
new
Location { City="Charleston", Distance=2421, Country="USA" },
new
Location { City="Helsinki", Distance=4771, Country="Finland" },
new
Location { City="Nice", Distance=5428, Country="France" },
new
Location { City="Dublin", Distance=4527, Country="Ireland" }
};
return cities;
}
}
}This allows me to then just write the below code in our
code-behind to get the same result as before:
Listing 11
using System;
using System.Collections.Generic;
using System.Web;
using System.Web.UI;
using System.Query;
public partial class Step3 : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
TravelOrganizer travel = new TravelOrganizer();
GridView1.DataSource = from location in travel.PlacesVisited
where location.Distance > 1000
orderby location.Country, location.City
select location;
GridView1.DataBind();
}
}What is really cool about LINQ is that it is
strongly-typed. What this means is that:
1) You get compile-time checking of all queries. Unlike SQL
statements today (where you typically only find out at runtime if something is
wrong), this means you will be able to check during development that your code
is correct (for example: if I wrote “distanse” instead of “distance” above the
compiler would catch it for me).
2) You will get intellisense within VS (and the free Visual
Web Developer) when writing LINQ queries. This makes both typing faster, but
also make it much easier to work against both simple and complex collection and
datasource object models.
