Add parent and child together by .NET EF6 code first

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according to the code in what I have tried section
BuySellHouse is parent
EstateImages is child
I tried to create a 1 to 0/1 relationship. I am not sure I did it correctly
inserting parent with child by code like this gives me an error

C#

BuySellHouse parent =new BuySellHouse();
EstateImages child=new EstateImages();
parent.EstateImages =child;
mydb.BuySellHouse.Add(parent);

the error
Unable to determine a valid ordering for dependent operations. Dependencies may exist due to foreign key constraints, model requirements, or store-generated values

What I have tried:

C#

public class BuySellHouse
    {
        public int Id { get; set; }
//other fields

        public int? EstateImagesId { get; set; }
        public  EstateImages EstateImages { get; set; }
    }

public class EstateImages
    {
        public int Id { get; set; }
//other fields

        public int BuySellHouseId { get; set; }
        public  BuySellHouse BuySellHouse { get; set; }
    }


 public  class BuySellHouseConfig : EntityTypeConfiguration<BuySellHouse>
    {
        public BuySellHouseConfig()
        {
            HasKey(x => x.Id);
            Property(x => 
            x.Id).HasDatabaseGeneratedOption(DatabaseGeneratedOption.Identity);
          
            ToTable("BuySellHouse");

           HasOptional(x => x.EstateImages).WithMany().HasForeignKey(x => 
           x.EstateImagesId).WillCascadeOnDelete(false);
        }
    }
public  class EstateImagesConfig : EntityTypeConfiguration<EstateImages>
    {
        public EstateImagesConfig()
        {
            HasKey(x => x.Id);
            Property(x => 
            x.Id).HasDatabaseGeneratedOption(DatabaseGeneratedOption.Identity);

            ToTable("EstateImages");
            HasRequired(x => x.BuySellHouse).WithMany().HasForeignKey(x => 
            x.BuySellHouseId).WillCascadeOnDelete(true);
        }
    }

Posted 2-Dec-21 21:53pm

4L4K1

Updated 2-Dec-21 22:38pm

v2

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Richard Deeming · Answer 1 · 2021-12-02T22:38:00

You've created both a one-to-one relationship (by convention) and two one-to-many relationships (by configuration). That's definitely not correct.

Based on your description, you need:

C#

public class BuySellHouse
{
    public int Id { get; set; }
    //other fields
    
    public int? EstateImagesId { get; set; }
    public EstateImages EstateImages { get; set; }
}

public class EstateImages
{
    public int Id { get; set; }
    //other fields

    public int BuySellHouseId { get; set; }
    public  BuySellHouse BuySellHouse { get; set; }
}


public  class BuySellHouseConfig : EntityTypeConfiguration<BuySellHouse>
{
    public BuySellHouseConfig()
    {
        HasKey(x => x.Id);
        Property(x => x.Id).HasDatabaseGeneratedOption(DatabaseGeneratedOption.Identity);
        ToTable("BuySellHouse");
    }
}

public  class EstateImagesConfig : EntityTypeConfiguration<EstateImages>
{
    public EstateImagesConfig()
    {
        HasKey(x => x.Id);
        Property(x => x.Id).HasDatabaseGeneratedOption(DatabaseGeneratedOption.Identity);
        ToTable("EstateImages");
        
        HasRequired(x => x.BuySellHouse).WithOptional(x => x.EstateImages).WillCascadeOnDelete(true);
    }
}

Fluent API - Relationships - EF6 | Microsoft Docs[^]