LINQ Query returning only 1 record

digink · May 23rd, 2010, 10:34 PM

I was just wondering what I could use to get ALL records returned that meet the where clause in this LINQ query, whenever I try to take out the FirstOrDefault() it gives me an error and doesn't seem to work properly without it.

With it it just shows the first record that meets those criteria when I'd like all of them to be displayed.

Any help would be greatly appreciated.

Code:

        Dim firstRecord = From r In myDataContext.Resorts _
                     Where r.ResortID = r.Listings.FirstOrDefault.ResortID _
                     And r.Listings.FirstOrDefault().ResortID = _
                     r.Pictures.FirstOrDefault().ResortID _
                     And r.Country = sCountry And r.State = sState _
                     And r.City = sCity _
                     Order By r.Listings.FirstOrDefault.SalePrice Ascending _
                     Select New With {r.ResortName, _
                                      .SalePrice = FormatCurrency(r.Listings.First().SalePrice, 0), _
                                      .RentPrice = FormatCurrency(r.Listings.First().RentPrice, 0), _
                                      r.Pictures.First().ImageUrl, _
                                      .ListingID = "~/ViewListing.aspx?ListingID=" & r.Listings.FirstOrDefault.ListingID & "&ResortID=" & r.ResortID}



        ListView1.DataSource = firstRecord
        ListView1.DataBind()

A little background, everything links back to the Resorts table via ResortID (two other tables which can be seen are Pictures and Listings).

Thanks!

Imar · May 24th, 2010, 03:50 AM

Hi there,

First of all, since this is not related to the book, can you please post this in a more appropriate forum such as the LINQ forum: http://p2p.wrox.com/linq-280/ or a general ASP.NET 3.5 forum: http://p2p.wrox.com/asp-net-3-5-436/

That said, there are three FirstOrDefault calls in your query so it's not really clear which one you would like to remove. It's also pretty unclear what you're trying to achieve, how things are related and what you want as a final result for the query and what you want to display.

In other words: can't help you here; except for a pointer to the 101 LINQ samples that show, among other things, how to use JOINs which is what you probably need: http://msdn.microsoft.com/en-us/vcsharp/aa336746.aspx.

Cheers,

Imar

digink · May 24th, 2010, 11:22 AM

Sorry about that Imar,

I checked out that link you posted regarding the LINQ queries and I found what I needed to get it working properly.

Thanks again.

Imar · May 24th, 2010, 11:44 AM

Excellent. Would you mind sharing how you fixed it?

Imar

digink · May 24th, 2010, 12:44 PM

Quote:

Originally Posted by Imar

Excellent. Would you mind sharing how you fixed it?

Imar

Sure, the updated query looks like this:

Code:

        Dim firstRecord = From r In myDataContext.Resorts, l In r.Listings _
                          Where r.ResortID = l.ResortID And l.ResortID = r.Pictures.FirstOrDefault().ResortID _
                          And r.Country = sCountry And r.State = sState And r.City = sCity _
                          Order By l.SalePrice Ascending _
                          Select New With {r.ResortName, _
                                      .SalePrice = FormatCurrency(l.SalePrice, 0), _
                                      .RentPrice = FormatCurrency(l.RentPrice, 0), _
                                      r.Pictures.FirstOrDefault().ImageUrl, _
                                      .ListingID = "~/ViewListing.aspx?ListingID=" & l.ListingID & "&ResortID=" & r.ResortID}



        ListView1.DataSource = firstRecord
        ListView1.DataBind()

Essentially since the only record I needed the FirstOrDefault of was the picture (can have multiple pictures per resort) it is the only thing I applied that to. For the listing I just had it set with the FK how it shows on the MSDN site and everything is now working beautifully.

LINQ is really powerful but man it is a little tricky at times.

Imar · May 24th, 2010, 12:50 PM

Quote:

LINQ is really powerful but man it is a little tricky at times.

Couldn't agree more.... ;-)

Imar