Using LINQ with ASP.NET (Part 1)
page 5 of 12
by Scott Guthrie
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Step 3: Refactoring the City Collection Slightly

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.


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User Comments

Title: linq   
Name: rohit
Date: 2012-10-11 5:04:12 AM
Comment:
thanks a lot,but need more explanation
Title: uk   
Name: hjkhjk
Date: 2012-07-30 2:22:48 AM
Comment:
hjkhjkhjkhjk
Title: Linq   
Name: hanston
Date: 2012-06-04 2:02:15 PM
Comment:
thanks a lot....but the images aren't shown.......
Title: Language Integrated Query   
Name: Daniel Kamroon
Date: 2012-03-14 7:22:12 AM
Comment:
Thank you very much. This has become my best material on LINQ topic. You made it very simple and understandable, thanks for sharing with us. Some other good articles on LINQ I was found over internet during searching this topic which also explained very well about LINQ, URL links of those posts are....
http://msdn.microsoft.com/en-us/library/bb907622.aspx
http://mindstick.com/Articles/9ca8fabd-49ef-4e4d-855b-74fc523d9138/?LINQ%20%28Language%20Integrated%20Query%29
http://www.codeproject.com/Articles/188935/LINQ-Demo-with-ASP-NET-Web-Application

Lastly, I would like to say thanks to everyone for your precious post.
Title: Sql Linq -simple query   
Name: Manish Vala
Date: 2011-02-12 4:23:52 AM
Comment:
protected void Page_Load(object sender, EventArgs e)
{
//DateTime d = DateTime.Now;

string[] Name = {" Manish"," Sunil", "Rohan", "Ashok", "Mahendra" };

GridView1.DataSource = from name in Name where name.Length > 5 orderby name select name.ToUpper();
GridView1.DataBind();}
Title: SQL LINQ-A query   
Name: Subhashini Janakiraman
Date: 2010-12-16 2:48:23 AM
Comment:
In the statement below which you have used,I want to know what Northwind refers to.Is it a dataset or a class?.Please reply me so.
Northwind db=new Northwind();
Title: thanks alot   
Name: avrail
Date: 2010-09-26 1:38:46 AM
Comment:
thanks a lot for this article
Title: Using LINQ with ASP.NET   
Name: S.Kumar
Date: 2010-04-08 3:52:48 PM
Comment:
Really a nice article, gave me a nice overview about LINQ
Title: er   
Name: sdf
Date: 2009-11-14 5:46:55 AM
Comment:
protected void Page_Load(object sender, EventArgs e)
{
string[] cities = { "London", "Amsterdam", "San Francisco", "Las Vegas",
"Boston", "Raleigh", "Chicago", "Charlestown",
"Helsinki", "Nice", "Dublin" };

GridView1.DataSource = from city in cities
where city.Length > 4
orderby city
select city.ToUpper();

GridView1.DataBind();
}
Title: nice   
Name: vice
Date: 2009-11-14 5:45:23 AM
Comment:
GridView1.DataSource = from city in cities
where city.Length > 4
orderby city
select city.ToUpper();
Title: jeyakumar   
Name: jayakumar
Date: 2009-11-14 5:40:46 AM
Comment:
it looking like me
Title: ok   
Name: kumar
Date: 2009-11-14 5:37:29 AM
Comment:
nice but not understand
Title: Topics   
Name: Dhanya
Date: 2009-10-19 6:09:06 AM
Comment:
I am not understand this topics..
Title: Trying To Get a Handle On This LINQ Stuff   
Name: Vibha Kant Pandey
Date: 2009-04-21 3:05:18 AM
Comment:
This article really enabled me to understand the concept of linq. the only problem i faced with this article is that i was not redirected to the correct place to download Linq May ctp
Title: About LINQs in ASP.NET   
Name: SitaRamReddy.Vempada
Date: 2009-04-01 5:47:16 AM
Comment:
This article help me a lot in LINQ concept, I thank to all who are in this unit

Thanks & Regards,
srvempada
Title: Using LINQ with ASP.NET (Part 1)   
Name: joseph jelasker
Date: 2009-03-28 1:52:20 AM
Comment:
This article really enabled me to understand the concept of linq. the only problem i faced with this article is that i was not redirected to the correct place to download Linq May ctp


Thanks a lot
Title: LINQ in 2005 and 2008   
Name: Manigandan
Date: 2008-12-16 6:38:07 AM
Comment:
1.We are having this LINQ concept in VS2005 itself...
What is extra facility added in VS2008.

2.If i want to install LINQ separately in VS2005, What is the software that i have to install?
Title: Good one   
Name: Shailendra
Date: 2008-12-09 2:24:22 AM
Comment:
Thanks for all, its very easy to know about linq from these articles.

thanks once again
Title: Trying To Get a Handle On This LINQ Stuff   
Name: D Wiley
Date: 2008-11-21 9:21:36 AM
Comment:
This is on of the best walkthroughs I have seen on the subject.
Title: Leraning LINQ   
Name: Manjeev kumar singh
Date: 2008-10-03 4:00:41 AM
Comment:
This one is most useful article LINQ on web. its really good start for how is beginner in LINQ....
Really thanks
Title: Using Richer Collections   
Name: Nithya K
Date: 2008-09-18 6:58:04 AM
Comment:
Now i got .Its my mistake.
It is very useful
Title: Using Richer Collections   
Name: Nithya K
Date: 2008-09-18 6:00:18 AM
Comment:
i got an error while executing
Title: Using Richer Collections   
Name: Nithya K
Date: 2008-09-18 5:53:19 AM
Comment:
\
\S
\
\
Title: Leraning LINQ   
Name: vanitha
Date: 2008-09-16 1:31:46 AM
Comment:
Very useful in learning the basic concepts of LINQ.
Title: Using LINQ with ASP.NET   
Name: Durai karthik M
Date: 2008-03-15 7:20:50 AM
Comment:
Very clear to understand the LINQ concept . Keep up the good work
Title: -   
Name: martin
Date: 2008-01-21 4:41:46 AM
Comment:
The images aren't shown... you need to remake the picture HTML






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