ansaurus

Question

Help creating an instance of a class using Linq and XML

Answer 1

A:

You've told it to create a new VisonData for each gcDiversityVision element in your document. The result is therefore a sequence of VisionData objects.

What are you actually trying to do - create one, or create many? There are lots of options available - if you give us more information about what you're trying to do, we can help you more.

Assuming you own the VisionData class, I would also suggest that you write a static VisionData.FromXElement method (or put it somewhere else) so that your query isn't quite so huge.

EDIT: Okay, based on the comment, it sounds like you don't want a LINQ query at all. Just:

XElement root = visionXml.Root;
VisionData newVisionData = new VisionData(...);

By the way, if you use the ToList extension method rather than new List<string>(...) it's likely to make the query a bit simpler. Or change the VisionData constructor to accept parameters of type IEnumerable<string> instead of List<string>, so you don't need to do the conversion within your constructor call at all.

Jon Skeet 2010-09-20 06:26:51

I am trying to create a single VisionData. gcDiversityVision is actually my root element in my xml. I have added the xml to give a better idea.

theDawckta 2010-09-20 06:41:10

@theDawckta: See my edit.

Jon Skeet 2010-09-20 06:48:26

What would I use in the "..." to grab the parameters for my VisionData object, can you give me a small example I can start with?

theDawckta 2010-09-20 07:07:23

@theDawckta: The same code you've already got. You know how to construct a `VisionData` object from an `XElement` - it's just you don't need to use a query.

Jon Skeet 2010-09-20 07:26:09

How will it know what data.descendants is though if I do not use this "from data in visionXML.Descendants(ns + "gcDiversityVision")"

theDawckta 2010-09-20 16:11:46

I have updated the code above, is this what you were thinking? Am I on the right track?

theDawckta 2010-09-20 16:23:27

@theDawckta: Yes, that would pretty much do it. I'm not sure what you're asking about "if you don't use `from data in visionXML.Descendants(...)`" - it will just use the data in the root element you've just parsed.

Jon Skeet 2010-09-20 16:38:49

I am now getting an error in this selection I am trying to make, not sure why new List<string>(root.Descendants(ns + "Employee").Select(f => f.Descendants(ns + "EmployeeIconImage").Select(ep => ep.Element(ns + "include").Attribute("externalPath").Value))),

theDawckta 2010-09-20 19:22:59

@theDawckta: "I am now getting an error" isn't very precise. You need to say *what* error you're getting.

Jon Skeet 2010-09-20 21:48:07

Answer 2

A:

I think you may need to modify your query like :

List<VisionData> newVisionData = (from data in visionXML.Descendants(ns + "gcDiversityVision")
                            select new VisionData(new List<string>(data.Descendants(ns + "Employee").Select(f => f.Element(ns + "EmployeeName").Value)),
                                            new List<string>(data.Descendants(ns + "Employee").Select(f => f.Element(ns + "EmployeeTitle").Value)),
                                            new List<string>(data.Descendants(ns + "Employee").Select(f => f.Element(ns + "include").Attribute("externalPath").Value)),
                                            new List<string>(data.Descendants(ns + "Employee").Select(f => f.Element(ns + "EmployeeVideo").Value)),
                                            data.Element(ns + "LinkHeaderText").Value,
                                            new List<string>(data.Descendants(ns + "Links").Select(f => f.Element(ns + "LinkURL").Value)),
                                            new List<string>(data.Descendants(ns + "Links").Select(f => f.Element(ns + "LinkText").Value)),
                                            new List<string>(data.Descendants(ns + "EmployeeStoryHeaderParagraph").Select(f => f.Element(ns + "EmployeeHeader").Value)),
                                            new List<string[]>(data.Descendants(ns + "EmployeeStoryHeaderParagraph").Select(f => f.Descendants(ns + "EmployeeParagraphs").Select(ep => ep.Element(ns + "EmployeeParagraph").Value).ToArray()))
                        )).ToList();

Siva Gopal 2010-09-20 06:37:51

I tried this but I am now gettign an exception, the exception occurs in the code you showed above I am not sure what is wrong with my Linq statement. I have included the xml in the original post.

theDawckta 2010-09-20 06:45:38

May i know, what is that error. Is that same as the one shown above?

Siva Gopal 2010-09-20 06:52:14

Line: 56Error: Unhandled Error in Silverlight Application Code: 4004 Category: ManagedRuntimeError Message: System.NullReferenceException: Object reference not set to an instance of an object. at gcDiversityVision.MainPage.xmlClient_DownloadStringCompleted(Object sender, DownloadStringCompletedEventArgs e) at System.Net.WebClient.OnDownloadStringCompleted(DownloadStringCompletedEventArgs e)

theDawckta 2010-09-20 07:10:20

Can you just put a break point and check whether the error is originating from the above LINQ code ?

Siva Gopal 2010-09-20 07:30:35

Here is the line that the error occurs, also I have updated the code above. new List<string>(visionXML.Descendants(ns + "Employee").Select(f => f.Element(ns + "include").Attribute("externalPath").Value)),

theDawckta 2010-09-20 16:22:26

ansaurus

tags:

views:

answers:

Help creating an instance of a class using Linq and XML

related questions