In pre EF6 view generation is known to be slow for bigger models. For now the solution is to use pregenerated views. This way you generate views at design time and are avoiding this work at runtime. To do that download EF power tools and select “Optimize Entity Data Model”. It will add a C# … Read more
You can use a beautiful thing called PredicateBuilder. Use it like this var pr = PredicateBuilder.False<User>(); foreach (var name in names) { pr = pr.Or(x => x.Name == name && x.Username == name); } return query.AsExpandable().Where(pr);
You can’t map two regular entities into same table. You have several choices: Use table splitting. Use custom query with projection to non entity type (as @Aducci proposed) Use QueryView Use database view or directly DefiningQuery Table splitting Table splitting allows you to map a table into two entities in 1:1 relation. First entity will … Read more
Ok I was banging my face off the keyboard for an hour with this. If your table’s Id field is an Identity field then it won’t work so use a different one for identifierExpression. I used the Name property and also removed the Id field from the new Hall {…} initializer. This tweak to the … Read more
You’ll need to use escape sequences like you would for any XML document, which is all the .config files are. Ampersand = & = & Greater Than = > = > Less Than = < = < Apostrophe=” = ' Quote = ” = " You can also use the CDATA tag so that you … Read more
The RTM version of Entity Framework 4.1 actually includes extension methods in the EntityFramework.dll file, for eager loading with lambda through the Include function. Just include the DLL in your project and you should be able to write code like: var princesses1 = context.Princesses.Include(p => p.Unicorns).ToList(); Remember to add an Import/Using statement to include the … Read more
Try this: Remove the constraint DF_Movies_Rating__48CFD27E before changing your field type. The constraint is typically created automatically by the DBMS (SQL Server). To see the constraint associated with the table, expand the table attributes in Object explorer, followed by the category Constraints as shown below: You must remove the constraint before changing the field type.
I’ve accepted @jfar’s answer because he put me on the right track, but thought i’d add an answer here for other people’s benefit. The reason the relationships were not getting updated is for the following reasons: 1) Completely disconnected scenario. ASP.NET = stateless, new context newed up each HTTP request. 2) Edited entity created by … Read more
To persist an entity you usually add it to it’s DbSet in the context. For example var bar = new Bar(); bar.Name = “foo”; var context = new Context(); context.Bars.Add(bar); Surprisingly, querying context.Bars, the just added entity cannot be found var howMany = context.Bars.Count(b => b.Name == “foo”); // howMany == 0 After context.SaveChanges() the … Read more
You delete your old .tt files You open your edmx file in designer mode (so you can see your model) Right click on a free space Select Add Code Generation Item In the dialog select “EF 6.x DbContext Code Generation Item” (something like this) Save your edmx and all classes will be generated for you, … Read more