Update error when a table has two foreign keys pointing to the same table

[fdahlberg]

Hi,

I have the following model:

public class Person
    {
        public Person()
        {
            Id = Guid.NewGuid();
            WorkItems = new List<WorkItem>();
        }

        public Guid Id { get; set; }

        public string Name { get; set; }

        public ICollection<WorkItem> WorkItems { get; set; }
    }

public class WorkItem
    {
        public WorkItem()
        {
            Id = Guid.NewGuid();
        }

        public Guid Id { get; set; }

        public string Description { get; set; }

        public Person Creator { get; set; }

    }

My fluent API looks like this:

protected override void OnModelCreating(DbModelBuilder modelBuilder)
        {
            base.OnModelCreating(modelBuilder);


            modelBuilder.Entity<Person>()
                .HasMany(p => p.WorkItems)
                .WithRequired()
                .WillCascadeOnDelete();
        }

When I use Graphdiff to update this small graph, I find that the Creator_Id Column in the WorkItem table is constantly set to the same as Person_id column.
I can't understand why this is happening. Is this a bug?

My graphdiff code to update the graph looks like this:

        public static void UpdatePerson(Person person)
        {
            using (var context = new GraphDiffTestDbContext())
            {
                context.Database.Log = s => System.Diagnostics.Debug.WriteLine(s);

                context.UpdateGraph(person, map => map
                .OwnedCollection(p => p.WorkItems, with => with.AssociatedEntity(p => p.Creator))
                );

                context.SaveChanges();
            }
        }

[JonathanMagnan]

Hello @fdahlberg ,

Thank you for reporting, I will try to check this issue tomorrow or during next week.

Best Regards,

Jonathan

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[cryo75]

This is not a GraphDiff problem but most probably something wrong with your entity configuration. How does your fluent API look like?

[fdahlberg]

Hi cryo75,
The fluent api that I'm using is part of the question.

[cryo75]

How are you mapping the properties to the columns?

And where is the Person_id column? In Person on in WorkItem?

[fdahlberg]

The Person_id column is created automatically by Entity Framework, because I have a naviagation property on Person (WorkItems).
The code above gives me the table structure that I'm after. But it's possible I could achieve this in a different way that would work with GraphDiff.

[cryo75]

So you have Person_Id and Creator_Id in the workitems table? Am I understanding correctly? And why do you want 2 foreign keys pointing to the same table?

I usually do my own mapping. However, what I can see is this:

context.UpdateGraph(person, map => map .OwnedCollection(p => p.WorkItems, with => with.AssociatedEntity(p => p.Creator)) );

Shouldn't that be:

context.UpdateGraph(person, map => map.OwnedCollection(p => p.WorkItems));

[fdahlberg]

That's correct! In my example (the real situation is much more complicated) I want to say that a person has a number of workitems, but the workitem is also created by a person (differenct from the owner). Therefore, as far as I can understand I need 2 foreign keys pointing to the same table (Person). Would you have solved it differently?

The Graphdiff mapping that you suggest is what I started with. I added the associated entity part as an attempt to solve it, but it didn't change anything.

[cryo75]

This is EF-related. I guess you will need another Person property (Owner) in your WorkItem because Creator will always be the same as Person.

[fdahlberg]

Tried adding a property on WorkItem called Owner and changing the fluen API to:
modelBuilder.Entity()
.HasMany(p => p.WorkItems)
.WithRequired(w => w.Owner)
.WillCascadeOnDelete();

Same result unfortunately.

Not sure it's EF related since it works fine if I add a Person object in the normal EF way. This is the code that works fine, meaning that only Owner_id is populated:

        public static void AddPerson()
        {

            var john = new Person { Name = "John" };

            var workItem1 = new WorkItem { Description = "Things to do" };

            john.WorkItems.Add(workItem1);


            using (var context = new GraphDiffTestDbContext())
            {
                context.Persons.Add(john);

                context.SaveChanges();
            }

        }

When I run the following graphdiff it doesn't work:

        public static void UpdatePerson()
        {

            var jenny = new Person { Name = "Jenny" };

            var workItem1 = new WorkItem { Description = "Stuff to do" };

            jenny.WorkItems.Add(workItem1);

            using (var context = new GraphDiffTestDbContext())
            {
                context.Database.Log = s => System.Diagnostics.Debug.WriteLine(s);

                context.UpdateGraph(jenny, map => map
                .OwnedCollection(p => p.WorkItems)
                );

                context.SaveChanges();
            }
        }

After having run these two methods the database looks like this:

So what I can't understand is why Creator_id is populated when I use graphdiff.

[cryo75]

Can you set up a sample project, zip it and attach it here so I can have a look at it.

[fdahlberg]

This is the project I'm using to test this issue:

GraphDiffTest.zip

[fdahlberg]

I know that it works fine when you're not using GraphDiff. My problem is when you use GraphDiff...

[cryo75]

I noticed. I'm getting the same Id's when using GraphDiff. Trying to see what the problem is.