The table could not be updated properly because it had no primary key. (Actually it had the column but the constraint was not copied when I did a SELECT INTO my dev table). The DataContext class requires a primary key for updates.
You aren’t deleting the object with the remove statement. Instead you are attempting to alter a record and make it an orphan (by setting the foreign key to null). The database has a non-null constraint on that column and prevents you from doing so.
This should do the trick: using (TestEntities db = new TestEntities()) { var query = from d in db.Dealership select new { Dealer = d, Parts = d.Part.Where ( p => p.Price < 100.0 && p.Supplier.Country == “Brazil” ), Suppliers = d.Part.Select(p => p.Supplier) }; var dealers = query.ToArray().Select(o => o.Dealer); foreach (var dealer in … Read more
Creating a new ObjectContext each time does involve ‘some’ overhead. Essentially the overhead involved is copying metadata from a global cache into metadata associated with the specific ObjectContext. This overhead is relatively minor, so often it is not worth worrying about, especially when you consider the extra safety inherent in the using pattern. For me … Read more
To answer the immediate question with a PowerShell v3+ solution: (Get-ChildItem -Force -Directory -Recurse -Depth 2 -Include ‘_svn’, ‘.svn’).Parent.FullName -Directory limits the matches to directories, -Recurse -Depth 2 recurses up to three levels (children, grandchildren, and great-grandchildren), Include allows specifying multiple (filename-component) filters, and .Parent.FullName returns the full path of the parent dirs. of the … Read more
I’ve fixed it myself now. It was a schoolboy error passing too many parameters to the CreateQuery(… ) call. Paste the following code into the Dynamic.cs file within the DynamicQueryable class for a dynamic Join extension method. You can find the source for the DynamicQuery sample project at http://code.msdn.microsoft.com/csharpsamples. Enjoy. public static IQueryable Join(this IQueryable … Read more
You can do LINQ to Objects and the use LINQ to calculate the totals: decimal sumLineTotal = (from od in orderdetailscollection select od.LineTotal).Sum(); You can also use lambda-expressions to do this, which is a bit “cleaner”. decimal sumLineTotal = orderdetailscollection.Sum(od => od.LineTotal); You can then hook this up to your Order-class like this if you … Read more
You can use the Linq methods that are defined in the System::Linq namespace, but you’ll have to jump through a couple extra hoops. First, C++/CLI doesn’t support extension methods. However, the extension methods are regular methods defined on various classes in System::Linq, so you can call them directly. List<int>^ list = gcnew List<int>(); int i … Read more
It looks like you’re trying to do the equivalent of a “WHERE…IN” condition. Check out How to write ‘WHERE IN’ style queries using LINQ to Entities for an example of how to do that type of query with LINQ to Entities. Also, I think the error message is particularly unhelpful in this case because .Contains … Read more
UPDATE: Actually I recently added another Tip that covers this, and provides an alternate probably better solution. The idea is to delay the use of Include() until the end of the query, see this for more information: Tip 22 – How to make include really include There is known limitation in the Entity Framework when … Read more