Re-building relationships can cause annotations to be lost

[ajcvickers]

In the code below a shadow FK property is specified when initially building the relationship. An annotation is then put on one of the navigations. The FK is then re-defined to be nullable. This results in the annotation no longer being present on the navigation, presumably because annotations were not copied when the relationship was re-built.

public class Context : DbContext
{
    public DbSet<Buyer> Buyers { get; set; }

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        modelBuilder.Entity<Buyer>()
            .HasMany(b => b.PaymentMethods)
            .WithOne()
            .HasForeignKey("BuyerId")
            .OnDelete(DeleteBehavior.Cascade);

        modelBuilder.Entity<Buyer>()
            .Metadata
            .FindNavigation(nameof(Buyer.PaymentMethods))
            .SetPropertyAccessMode(PropertyAccessMode.Field);

        modelBuilder.Entity<PaymentMethod>()
            .Property<int>("BuyerId").IsRequired();

        // Fails
        Debug.Assert(modelBuilder.Entity<Buyer>()
                         .Metadata
                         .FindNavigation(nameof(Buyer.PaymentMethods))
                         .GetPropertyAccessMode() == PropertyAccessMode.Field);
    }
}

public class Buyer
{
    public int Id { get; set; }

    public ICollection<PaymentMethod> PaymentMethods { get; set; }
}

public class PaymentMethod
{
    public int Id { get; set; }
}

Model before FK is made non-nullable:

Model: 
  EntityType: Buyer
    Properties: 
      Id (int) Required PK ReadOnlyAfterSave RequiresValueGenerator ValueGenerated.OnAdd 0 0 0 -1 0
    Navigations: 
      PaymentMethods (<PaymentMethods>k__BackingField, ICollection<PaymentMethod>) Collection ToDependent PaymentMethod PropertyAccessMode.Field 0 -1 1 -1 -1
        Annotations: 
          PropertyAccessMode: Field
    Keys: 
      Id PK
    Annotations: 
      Relational:TableName: Buyers
      RelationshipDiscoveryConvention:NavigationCandidates: System.Collections.Immutable.ImmutableSortedDictionary`2[System.Reflection.PropertyInfo,System.Type]
  EntityType: PaymentMethod
    Properties: 
      Id (int) Required PK ReadOnlyAfterSave RequiresValueGenerator ValueGenerated.OnAdd 0 0 0 -1 0
      BuyerId (no field, Nullable<int>) Shadow FK Index 1 1 1 0 1
    Keys: 
      Id PK
    Foreign keys: 
      BuyerId -> Buyer.Id ToDependent: PaymentMethods
    Annotations: 
      RelationshipDiscoveryConvention:NavigationCandidates: System.Collections.Immutable.ImmutableSortedDictionary`2[System.Reflection.PropertyInfo,System.Type]
Annotations: 
  ProductVersion: 1.1.0-rtm-22752
  SqlServer:ValueGenerationStrategy: IdentityColumn

Model after FK is made nullable:

Model: 
  EntityType: Buyer
    Properties: 
      Id (int) Required PK ReadOnlyAfterSave RequiresValueGenerator ValueGenerated.OnAdd 0 0 0 -1 0
    Navigations: 
      PaymentMethods (<PaymentMethods>k__BackingField, ICollection<PaymentMethod>) Collection ToDependent PaymentMethod 0 -1 1 -1 -1
    Keys: 
      Id PK
    Annotations: 
      Relational:TableName: Buyers
      RelationshipDiscoveryConvention:NavigationCandidates: System.Collections.Immutable.ImmutableSortedDictionary`2[System.Reflection.PropertyInfo,System.Type]
  EntityType: PaymentMethod
    Properties: 
      Id (int) Required PK ReadOnlyAfterSave RequiresValueGenerator ValueGenerated.OnAdd 0 0 0 -1 0
      BuyerId (no field, int) Shadow Required FK Index 1 1 1 0 1
    Keys: 
      Id PK
    Foreign keys: 
      BuyerId -> Buyer.Id ToDependent: PaymentMethods
    Annotations: 
      RelationshipDiscoveryConvention:NavigationCandidates: System.Collections.Immutable.ImmutableSortedDictionary`2[System.Reflection.PropertyInfo,System.Type]
Annotations: 
  ProductVersion: 1.1.0-rtm-22752
  SqlServer:ValueGenerationStrategy: IdentityColumn

[AndriySvyryd]

Related to #1923

[andrelmp]

had the same issue, it took almost a day trying to figure out why SetPropertyAccessMode doesn't work.
Thanks @ajcvickers saved my day

[TsengSR]

Thanks @ajcvickers! This one bite me too and I spent 4 days trying to hunt it down, until I finally realized that the .SetField call is being ignored and EF Core always used the Navigation property!

Pushing the .SetField and SetPropertyAccessMode after the relationships worked as a workaround.