Question

I’m trying to join one Linq collection from Data Base and one from XML file. Is this possible? I always get: Local sequence cannot be used in LINQ to SQL implementation of query operators except the Contains() operator.

Here is my code:

MyDataContext dc = new MyDataContext(); XElement CustomData;  var pages = from p in dc.Pages             select new             {                 Title = p.Title,                 Slug = p.Slug,                 PageId = p.PageId.ToString()             };  var orders = from p in CustomData.Element('pages').Elements('page')              select new              {                  PageId = (string)p.Attribute('id'),                  SortOrder = (int)p.Attribute('sortOrder')              };   var source = from p in pages              join o in orders              on p.PageId equals o.PageId              select p;  source.ToList(); 

Answer 1

I don’t think you need to do the join at all.

MyDataContext dc = new MyDataContext(); XElement CustomData;  var orders = CustomData.Element('pages').Elements('page')                        .Select( o =>  new                          {                              PageId = p.Attribute('id').ToString(),                              SortOrder = (int)p.Attribute('sortOrder')                          });  var source = dc.Pages                .Where( p => orders.Select( o => o.PageId)                                   .Contains( p.PageId.ToString() ))                .Select( p => new                 {                   Title = p.Title,                   Slug = p.Slug,                   PageId = p.PageId.ToString()                 });