Entity Framework has no support for triggers, although you can certainly manually execute a statement that would create a trigger, but you would need to do this after the table was created (if using migrations). You can use the technique specified by Ladislav in EF 4.1 code-first adding a trigger to a table Take note … Read more
Looking through the GitHub issues, there is no DbEntityValidationException equivalent in Entity Framework Core. There’s a blog post (linked from issue #9662 on GitHub), that gives a code example for performing the validation logic yourself, included here for completeness: class MyContext : DbContext { public override int SaveChanges() { var entities = from e in … Read more
This is 2 years old but I was just in the same situation so it is still relevant. It’s first result on Google for this error. So I can see in your Screenshot that you are not in the standard Windows Visual Studio so I assume you are not on Windows (makes a difference in … Read more
You are seeing this because you delete objects from a collection that currently has active operations on. More specifically you are updating the Kids collection and then executing the Any() operator on it in the while loop. This is not a supported operation when working with IEnumerable instances. What I can advice you to do … Read more
Try accessing PageTitle directly in ThenInclude: using (var dbContext = new BookContext()) { var bookPages = dbContext .Book .Include(x => x.Pages) .ThenInclude(y => y.PageTitle) .SingleOrDefault(x => x.BookId == “some example id”) .Select(x => x.Pages) .Select(x => x.PageTitle) .ToList(); }
The problem is that when you have multiple relationships between two entities, EF Code First isn’t able to find out which navigation properties match up, unless, you tell it how, here is the code: public class Client { [DatabaseGenerated(DatabaseGeneratedOption.Identity)] public int ID { get; set; } public string ClientName { get; set; } /****Change Nullable<int> … Read more
Install Entity Framework Power Tools Beta 4, restart Visual Studio, right-click on the context in your solution view and you’ll see a new ‘Entity Framework’ option in the context menu. Select ‘View Entity Data Model’ to see a beautiful visual database diagram in Visual Studio. Voilà! Entity Framework 6 Power Tools: Link
I think you are trying to specify database column type. You could use data annotations as described in this article. Here is an example : [Table(“People”)] public class Person { public int Id { get; set; } [Column(TypeName = “varchar”)] public string Name { get; set; } [Column(TypeName=”date”)] public DateTime DOB { get; set; } … Read more
I realized that the problem was that the Merchant class did not meet requirements for proxy generation. Specifically, I needed to add a protected parameterless constructor. I only had a private one.
This is the proper way of creating a PK without Identity Autoincrement enabled: [Key] [DatabaseGenerated(DatabaseGeneratedOption.None)] public string FooId { get; set; }