Question

In this situation I am trying to perform a data import from an XML file to a database using LINQ to XML and LINQ to SQL.

Here’s my LINQ data model:

public struct Page {     public string Name;     public char Status;     public EntitySet<PageContent> PageContents;  } public struct PageContent {     public string Content;     public string Username;     public DateTime DateTime; } 

Basically what I’m trying to do is write a query that will give me a data structure that I can just submit to my LINQ Data Context.

IEnumerable<Page> pages = from el in doc.Descendants()                           where el.Name.LocalName == 'page'                           select new Page()                 {                     Name = el.Elements().Where(e => e.Name.LocalName == 'title').First().Value,                     Status = 'N',                     PageContents = (from pc in el.Elements()                                     where pc.Name.LocalName == 'revision'                                     select new PageContent()                                     {                                        Content = pc.Elements().Where(e => e.Name.LocalName=='text').First().Value,                                        Username = pc.Elements().Where(e => e.Name.LocalName == 'contributor').First().Elements().Where(e => e.Name.LocalName == 'username').First().Value,                                        DateTime = DateTime.Parse(pc.Elements().Where(e => e.Name.LocalName == 'timestamp').First().Value)                                     }).ToList()                 }; 

The problem is in the sub-query. I have to somehow get my object collection into the EntitySet container. I can’t cast it (oh lord how I’ve tried) and there’s no EntitySet() constructor that would seem to help.

So, can I write a LINQ query that will populate the EntitySet<PageContent> data with my IEnumerable<Page> data?

Answer 1

you can construct your entity set from a IEnumerable using a helper class, something like:

public static class EntityCollectionHelper {     public static EntitySet<T> ToEntitySet<T>(this IEnumerable<T> source) where T:class     {         EntitySet<T> set = new EntitySet<T>();         set.AddRange(source);         return set;     } } 

and use it like so :

PageContents = (from pc in el.Elements()                                 where pc.Name.LocalName == 'revision'                                 select new PageContent()                                 {                                    Content = pc.Elements().Where(e => e.Name.LocalName=='text').First().Value,                                    Username = pc.Elements().Where(e => e.Name.LocalName == 'contributor').First().Elements().Where(e => e.Name.LocalName == 'username').First().Value,                                    DateTime = DateTime.Parse(pc.Elements().Where(e => e.Name.LocalName == 'timestamp').First().Value)                                 }).ToEntitySet()