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Hello everyone I can't find a solution to this problem, I have an Entity that have a property created like this on DbModelBuilder

First a class with a property RelatedFoo which is a list to the same Foo Entity

public class Foo
    {
        public int FooId { get; set; }
        public string Name { get; set; }

        public virtual List<Foo> RelatedFoo { get; set; }
    }

This was created in DbContext

modelBuilder.Entity<Foo>()
        .HasMany(p => p.RelatedFoo)
        .WithMany()
        .Map(m =>
        {
            m.MapLeftKey("FooId");
            m.MapRightKey("RelatedFooId");
            m.ToTable("RelatedFoos");                
        });

This result in a migration is like this

CreateTable(
            "dbo.RelatedFoos",
            c => new
                {
                    FooId= c.Int(nullable: false),
                    RelatedFooId= c.Int(nullable: false),
                })
            .PrimaryKey(t => new { t.FooId, t.RelatedFooId })
            .ForeignKey("dbo.Foo", t => t.FooId)
            .ForeignKey("dbo.Foo", t => t.RelatedFooId )
            .Index(t => t.FooId)
            .Index(t => t.RelatedFooId );

Everything works as expected, I can do something like: 

//Create new list of relatedFoos        
List<Foo> relatedFoos = new List<Foo>();
//Add Foo entities to this list
relatedFoos.Add(fooEntity1);
relatedFoos.Add(fooEntity2);
//Add this List to a main Foo entity
Foo mainFooEntity.RelatedFoo = relatedFoos;
//Save this
db.Entry(mainFooEntity).State = EntityState.Modified;
db.SaveChanges();

And the relatedFoos are saved in the new table (RelatedFoos)

The problem comes when I try to delete this relatedFoos... I've already tried:

//Starting from a main Foo Entity
mainFooEntity.RelatedFoo = null;
db.Entry(mainFooEntity).State = EntityState.Modified;
db.SaveChanges();

This does not delete the data of "RelatedFoos" neither does assigning mainFooEntity.RelatedFoo to an empty List<Foo> or either deleting the current data. How can I delete this List<>?

Siavash
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BeN
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  • Is it possible that because of lazy loading when you fetch a mainFooEntity from db the list is already empty? – roozbeh S Oct 30 '18 at 18:10
  • Thanks @roozbeh at the time of read mainFooEntity I ckeck that RelatedFoo is populated, on the Model is declared as virtual property so is always populated. I can't find how delete the related List... :( – BeN Oct 30 '18 at 18:17
  • https://learn.microsoft.com/en-us/ef/core/saving/cascade-delete – crunchy Oct 30 '18 at 18:20
  • Thanks @crunchy that have effect when I delete de principal entity in this case If I Delete mainFooEntity this is deleted, but my objective is delete the related (List) of the property RelatedFoo when Update the mainFooEntity. – BeN Oct 30 '18 at 19:09

1 Answers1

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I can't find a solution to this, so I end creating by myself a new Entitie "RelatedFoos" but whitout modelBuilder, this new entitie it's only a relationship table for create "Foo" against "Foo" N relations.

I create the Model and add to DbContext, create migration, so, in this way I can use this Model Class for make updates or deletes without problem.

Thanks in advance.

BeN
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