ASP.NET Core, EF Core One-to-One and One-to-Many at once

Question

I am currently working with ASP.NET core. I have a BaseModel and SubModel which is structured like this:

class BaseClass{
   SubClass MainSubClass {get;set;}
   List<SubClass> SubClasses {get;set;} 
}

When I try to add migrations with this, I get this error:

Unable to determine the relationship represented by navigation property 'StoreModel.StoreMainPhoto' of type 'StorePhotoModel'. Either manually configure the relationship, or ignore this property from the model.`*

The real data models are...

in StoreModel.cs

[Table("Stores")]
public class StoreModel
{

    [Key]
    public int Id { get; set; }

    [Required]
    [MaxLength(25)]
    public string StoreName { get; set; }

    [MaxLength(80)]
    public string StoreShortDescription { get; set; }

    [MaxLength(4000)]
    public string StoreFullDescription { get; set; }

    public string StoreLocation { get; set; }
    public string StoreAddress { get; set; }


    #region graphics Data
    public StorePhotoModel StoreMainPhoto { get; set; }
    public ICollection<StorePhotoModel> StorePhotos { get; set; }
    #endregion

    public ICollection<MenuModel> Menus { get; set; }
    public ICollection<StoreReviewModel> StoreReviews { get; set; }

    #region store contacts
    public string StorePhoneNumber { get; set; }
    public string StoreExtraContacts { get; set; }
    #endregion

    public StoreModel()
    {
        StorePhotos = new Collection<StorePhotoModel>();
        Menus = new Collection<MenuModel>();
        StoreReviews = new Collection<StoreReviewModel>();
    }
}

in StorePhotoModel.cs

[Table("StorePhotos")]
public class StorePhotoModel : MediaModel
{

    // base Store
    public int BaseStoreId { get; set; }
    [ForeignKey(nameof(BaseStoreId))]
    public StoreModel BaseStore { get; set; }
}

Answer 1

Entity Framework is confused to what the relationship between these two models is.

In StoreModel you have this:

public StorePhotoModel StoreMainPhoto { get; set; } //one to one
public ICollection<StorePhotoModel> StorePhotos { get; set; } //one to many

Which would indicate that StoreModel has a one to one and and one to many relationships with StorePhotoModel.

You have not indicated in the question what the relationship should be though so I cannot comment on which would be correct.

Update

Try this:

[Table("Stores")]
public class StoreModel
{

    [Key]
    public int Id { get; set; }

    [Required]
    [MaxLength(25)]
    public string StoreName { get; set; }

    [MaxLength(80)]
    public string StoreShortDescription { get; set; }

    [MaxLength(4000)]
    public string StoreFullDescription { get; set; }

    public string StoreLocation { get; set; }
    public string StoreAddress { get; set; }

    public int StoreMainPhotoId {get;set;}


    #region graphics Data
    [ForeignKey(nameof(StoreMainPhotoId))]
    public StorePhotoModel StoreMainPhoto { get; set; }
    public ICollection<StorePhotoModel> StorePhotos { get; set; }
    #endregion

    public ICollection<MenuModel> Menus { get; set; }
    public ICollection<StoreReviewModel> StoreReviews { get; set; }

    #region store contacts
    public string StorePhoneNumber { get; set; }
    public string StoreExtraContacts { get; set; }
    #endregion

    public StoreModel()
    {
        StorePhotos = new Collection<StorePhotoModel>();
        Menus = new Collection<MenuModel>();
        StoreReviews = new Collection<StoreReviewModel>();
    }
}

Update 2

You can override the OnModelCreating to something like this.

protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
    modelBuilder.Entity<StoreModel>()
        .HasMany(x => x.StorePhotos)

    modelBuilder.Entity<StoreModel>()
        .HasRequired(x => x.StoreMainPhoto)
        .HasForeignKey(x => x.StoreMainPhotoId)
}

Please note this is untested so you may need to tweak. You can find similar questions to yours here:

• Both One-To-One and One-To-Many relationships in Entity Framework 5 Code First

• Entity Framework Code First: How can I create a One-to-Many AND a One-to-One relationship between two tables?

• Entity Framework Code First: How can I create a One-to-Many AND a One-to-One relationship between two tables?