Relationship on owned type

Question

I want to define a one to many relationship on an owned type.

Here in my example,

• InboundRequest: principal entity

• RequestHistory: owned type

• RequestHistoryEntry : Dependency entity

public class InboundRequest : IAggregateRoot
{
    public int Id { get; private set; }
    public RequestHistory History { get; private set; }
}
public class RequestHistory
{
    public IList<RequestHistoryEntry> HistoryEntries { get; set; }
}

public class RequestHistoryEntry
{
    public RequestState State { get; private set; }
    public DateTime Timestamp { get; private set; }
    public int Id { get; set; }
}

builder.Entity<InboundRequest>().OwnsOne(x => x.History);

Unfortunately EF Core gives me the following error:

The relationship from 'RequestHistoryEntry' to 'InboundRequest.History#RequestHistory.HistoryEntries' is not supported because the owned entity type 'InboundRequest.History#RequestHistory' cannot be on the principal side.

Is there a way to have a one to many relationship between an owned type and a list of dependencies?

Answer 1

The only way to have a one to many relationship with owned types is if the owned entity is on the many side of the relationship, in which case ef core will map it to a separate table by convention. What you are attempting is per se not possible by design. However, in your particular case, why don't you get rid of RequestHistory altogether and make the list of RequestHistoryEntry as a collection of owned type to your InboundRequest as follows:

public class InboundRequest : IAggregateRoot
{
    public int Id { get; private set; }
    public IList<RequestHistoryEntry> HistoryEntries { get; set; }
}

public class RequestHistoryEntry
{
    public RequestState State { get; private set; }
    public DateTime Timestamp { get; private set; }
    public int Id { get; set; }
}

builder.Entity<InboundRequest>().OwnsMany(x => x.HistoryEntries);

That should get rid of the error as well as achieve your desired relationship to your dependent entity.