Joining Returned SQL Data Services Responses

By James at February 05, 2009 05:08
Filed Under: SQL Data Services, SQL Services, Web Development

In preparing for my talk on SDS at last month’s Code Camp, I needed to figure out a way to join to SQL Data Services responses. I came up with this method using LINQ. I don’t know if its the best way to do it, but it works for me. I’d appreciate any feedback.


1. Master Page – Page_Load calls GetPodcasts()

2. GetPodcasts() gets two SDS responses, podCastDoc and guestDoc, does some LINQ, then returns a System.Linq.Enumerable

3. A ListView on the Master Page is bound to the podcast object.


Method GetPodcasts()

   1: public void GetPodcasts()
   2: {
   3:     AT_Podcasts at_Podcasts = new AT_Podcasts();
   4:     AT_Guests at_Guests = new AT_Guests();
   5:     XElement podCastDoc = at_Podcasts.SelectPodcasts();
   6:     XElement guestDoc = at_Guests.SelectGuests();
   8:     if (podCastDoc != null && guestDoc != null)
   9:     {
  10:         var podcasts = from podcast in podCastDoc.Descendants("at-podcastdata")
  11:                        join guest in guestDoc.Descendants("at-guest")
  12:                        on (string)podcast.Element("GuestID").Value
  13:                        equals (string)guest.Element("GuestName").Value
  14:                        orderby (DateTime)podcast.Element("PublishDate")
  15:                        select new
  16:                       {
  17:                           PodCastId = podcast.Element("PodCastDataId").Value,
  18:                           PodCastTitle = podcast.Element("PodCastTitle").Value,
  19:                           PodCastPublishDate = DateTime.Parse(podcast.Element("PublishDate").Value).ToLongDateString(),
  20:                           PodCastAbstract = podcast.Element("Abstract").Value,
  21:                           RunTime = podcast.Element("RunTime").Value,
  22:                           GuestID = podcast.Element("GuestID").Value,
  23:                           GuestName = guest.Element("FullGuestName").Value,
  24:                           GuestCompany = guest.Element("GuestCompany").Value
  25:                       };
  26:         lvPodCasts.DataSource = podcasts;
  27:         lvPodCasts.DataBind();
  28:     }
  29: }


Method at_Podcasts.SelectPodcasts()

   1: public XElement SelectPodcasts()
   2:     {
   3:         XElement atPodCasts;
   4:         AT_SDSConfig config = AT_SDSConfig.Create();
   5:         Uri container = config.GetPodCastDataContainer();
   6:         string uri = container.ToString() + "?q=";
   7:         var request = AT_SDSUtils.CreateRequest(config, new Uri(uri), "GET", string.Empty);
   8:         try
   9:         {
  10:             var response = (HttpWebResponse)request.GetResponse();
  11:             using (var stream = response.GetResponseStream())
  12:             using (var reader = new System.IO.StreamReader(stream))
  13:             {
  14:                 XmlTextReader r = new XmlTextReader(reader);
  15:                 atPodCasts = XElement.Load(r);
  16:                 return atPodCasts;
  17:             }
  18:         }
  19:         catch (WebException ex)
  20:         {
  21:             AT_SDSUtils.OutputException(ex);
  22:             return null;
  23:         }
  24:     }

NOTE: at_Guests.SelectGuests() is similar, just going into the Guest Container


Results of SelectPodcasts()

   1: <s:EntitySet xmlns:s="" xmlns:xsi="" xmlns:x="">  
   2:   <at-podcastdata>
   3:     <s:Id>getting-restful</s:Id>
   4:     <s:Version>539244</s:Version>
   5:     <PodCastDataId xsi:type="x:string">getting-restful</PodCastDataId>
   6:     <PodCastTitle xsi:type="x:string">Getting RESTful</PodCastTitle>
   7:     <RunTime xsi:type="x:string">48:25</RunTime>
   8:     <Description xsi:type="x:string">Volkan talks about how to work with REST and process the XML with LINQ</Description>
   9:     <AdminNotes xsi:type="x:string">Great episode</AdminNotes>
  10:     <Abstract xsi:type="x:string">REST, XML and LINQ</Abstract>
  11:     <IsPublished xsi:type="x:boolean">true</IsPublished>
  12:     <GuestID xsi:type="x:string">volkan-uzun</GuestID>
  13:     <CreateDate xsi:type="x:string">1/23/2009 12:00:00 AM</CreateDate>
  14:     <PublishDate xsi:type="x:string">2/20/2009 12:00:00 AM</PublishDate>
  15:   </at-podcastdata>
  16:   <at-podcastdata>
  17:     <s:Id>sql-data-services</s:Id>
  18:     <s:Version>539554</s:Version>
  19:     <PodCastDataId xsi:type="x:string">sql-data-services</PodCastDataId>
  20:     <PodCastTitle xsi:type="x:string">SQL Data Services</PodCastTitle>
  21:     <RunTime xsi:type="x:string">12:35</RunTime>
  22:     <Description xsi:type="x:string">Jennifer goes into detail about how to use SQL Data Services to run a web site.</Description>
  23:     <AdminNotes xsi:type="x:string">This is the first podcast</AdminNotes>
  24:     <Abstract xsi:type="x:string">Using SQL Data Services to run a website</Abstract>
  25:     <IsPublished xsi:type="x:boolean">true</IsPublished>
  26:     <GuestID xsi:type="x:string">jennifer-louie</GuestID>
  27:     <CreateDate xsi:type="x:string">1/24/2009 12:00:00 AM</CreateDate>
  28:     <PublishDate xsi:type="x:string">1/24/2009 12:00:00 AM</PublishDate>
  29:   </at-podcastdata>
  30:   <at-podcastdata>
  31:     <s:Id>working-with-office-2007</s:Id>
  32:     <s:Version>539227</s:Version>
  33:     <PodCastDataId xsi:type="x:string">working-with-office-2007</PodCastDataId>
  34:     <PodCastTitle xsi:type="x:string">Working with Office 2007</PodCastTitle>
  35:     <RunTime xsi:type="x:string">30:45</RunTime>
  36:     <Description xsi:type="x:string">In this episode, Joe talks about a cool macro he wrote that makes all the busy work his boss has him do, a lot more fun.</Description>
  37:     <AdminNotes xsi:type="x:string">Kinda flakey, but ok to publish</AdminNotes>
  38:     <Abstract xsi:type="x:string">Office 2007 Macros</Abstract>
  39:     <IsPublished xsi:type="x:boolean">true</IsPublished>
  40:     <GuestID xsi:type="x:string">joe-blow</GuestID>
  41:     <CreateDate xsi:type="x:string">1/23/2009 12:00:00 AM</CreateDate>
  42:     <PublishDate xsi:type="x:string">2/11/2009 12:00:00 AM</PublishDate>
  43:   </at-podcastdata>
  44: </s:EntitySet>

Results of SelectGuests()

   1: <s:EntitySet xmlns:s="" xmlns:xsi="" xmlns:x="">
   2:   <at-guest>
   3:     <s:Id>jennifer-louie</s:Id>
   4:     <s:Version>50343029</s:Version>
   5:     <GuestName xsi:type="x:string">jennifer-louie</GuestName>
   6:     <FullGuestName xsi:type="x:string">Jennifer Louie</FullGuestName>
   7:     <GuestEmail xsi:type="x:string"></GuestEmail>
   8:     <GuestCompany xsi:type="x:string">Louie Software</GuestCompany>
   9:     <GuestBio xsi:type="x:string">Jennifer is a .NET Rock Star. She's really cute and hot!</GuestBio>
  10:     <PublishEmail xsi:type="x:boolean">true</PublishEmail>
  11:   </at-guest>
  12:   <at-guest>
  13:     <s:Id>james-johnson</s:Id>
  14:     <s:Version>50404939</s:Version>
  15:     <GuestName xsi:type="x:string">james-johnson</GuestName>
  16:     <FullGuestName xsi:type="x:string">James Johnson</FullGuestName>
  17:     <GuestEmail xsi:type="x:string"></GuestEmail>
  18:     <GuestCompany xsi:type="x:string">Duringlunch</GuestCompany>
  19:     <GuestBio xsi:type="x:string">James is a .NET Developer who has been writing software since punch cards. He often remembers the time when his Computer Science PhD project got scattered to the wind, when he stumbled across a brand new orange screen monitor and his breath was taken away.</GuestBio>
  20:     <PublishEmail xsi:type="x:boolean">true</PublishEmail>
  21:   </at-guest>
  22:   <at-guest>
  23:     <s:Id>volkan-uzun</s:Id>
  24:     <s:Version>49928700</s:Version>
  25:     <GuestName xsi:type="x:string">volkan-uzun</GuestName>
  26:     <FullGuestName xsi:type="x:string">Volkan Uzun</FullGuestName>
  27:     <GuestEmail xsi:type="x:string"></GuestEmail>
  28:     <GuestCompany xsi:type="x:string">Uzun Enterprises</GuestCompany>
  29:     <GuestBio xsi:type="x:string">Inland Empire .NET User's Group Most Valuable Member - 2007/2008. LINQ Expert. Nice Guy.</GuestBio>
  30:     <PublishEmail xsi:type="x:boolean">true</PublishEmail>
  31:   </at-guest>
  32: </s:EntitySet>


Back to the LINQ which does the join

   1: var podcasts = from podcast in podCastDoc.Descendants("at-podcastdata")
   2:    join guest in guestDoc.Descendants("at-guest")
   3:    on (string)podcast.Element("GuestID").Value
   4:    equals (string)guest.Element("GuestName").Value
   5:    orderby (DateTime)podcast.Element("PublishDate")
   6:    select new
   7:   {
   8:       PodCastId = podcast.Element("PodCastDataId").Value,
   9:       PodCastTitle = podcast.Element("PodCastTitle").Value,
  10:       PodCastPublishDate = DateTime.Parse(podcast.Element("PublishDate").Value).ToLongDateString(),
  11:       PodCastAbstract = podcast.Element("Abstract").Value,
  12:       RunTime = podcast.Element("RunTime").Value,
  13:       GuestID = podcast.Element("GuestID").Value,
  14:       GuestName = guest.Element("FullGuestName").Value,
  15:       GuestCompany = guest.Element("GuestCompany").Value
  16:   };
  17: lvPodCasts.DataSource = podcasts;
  18: lvPodCasts.DataBind();




Again, like I said. I’d appreciate your comments.


Comments (1) -

2/5/2009 9:42:20 AM #

Matt Penner

Hey James,
Check out my post on your session from Code Camp:

At the very bottom I have a couple of paragraphs regarding your join.  The problem issue I see is that you have to grab your entire set of Podcasts and Guests before the join.  It's not a big deal now but in the future this could lead to hundreds of results and you can't do any filtering prior to the load.

At Code Camp it seems that Bret Stateham gave a demo on using lamda expressions in the REST url.  I couldn't find that exactly but here is a similar post using SDS:

Also, PhluffyPhotos ( is a project on Code Plex where they have created their own Linq-to-SDS solution.

Check it out!

Matt Penner | Reply

Add comment

  Country flag
  • Comment
  • Preview

About the author

James James is a five time and current Microsoft MVP in Client App Development, a Telerik Insider, a past Director on the INETA North America Board, a husband and dad, and has been developing software since the early days of Laser Discs and HyperCard stacks. As the Founder and President of the Inland Empire .NET User's Group, he has fondly watched it grow from a twice-a-month, early Saturday morning group of five in 2003, to a robust and rambunctious gathering of all types and sizes of .NET developers.

James loves to dig deep into the latest cutting edge technologies - sometimes with spectacular disasters - and spread the word about the latest and greatest bits, getting people excited about developing web sites and applications on the .NET platform, and using the best tools for the job. He tries to blog as often as he can, but usually gets distracted by EF, LINQ, MVC, ASP, SQL, XML, and most other types of acronyms. To keep calm James plays a mean Djembe and tries to practice his violin. You can follow him on twitter at @latringo.

And as usual, the comments, suggestions, writings and rants are my own, and really shouldn't reflect the opinions of my employer. That is, unless it really does.

James Twitter Feed

Recent Comments

Comment RSS

Month List