Serialize Money with Entity Framework Core 2.0

[ghost]

Hi, Since Noda's Money is a struct type, we cannot use it as field type for our entities in our .Net Core 2.0 project, using Entity Framework Core 2.0.

Since EF Core 2.0 now fully supports owned entities, it would be great to be able to do that!

Could you advise us a way to do that? Thanks

[bugproof]

Yes, I'm just thinking as well how to integrate it with EF Core, I will somehow need to persist all the currencies in the database to refer to them in the other entities. I started to create all those money entities myself but I don't think it's reasonable when a great library like NodaTime exists.

[andriysavin]

Owned entities have mostly the same traits as regular entities, so they are required to be reference types (so the change tracker can track them). A value convertor is not an option as well, because it can't convert an object to multiple objects (e.g. amount and currency) so they could be mapped to multiple DB columns. I had to wrap Money struct into my own reference type (configured as owned entity) to work around this.

[chrisbbe]

@andriysavin Interesting approach, it seems like the EF team will provide support for value converters to map to multiple DB columns in the release of EF Core 6.

Meanwhile, are you interested in sharing your Money wrap workaround code?

[andriysavin]

@chrisbbe It's as simple as this:

public sealed class Price
        : IComparable<Price?>, IEquatable<Price?>
{
        private readonly Money price;

        public decimal Amount => price.Amount;
        public string Currency => price.Currency.Code;

        public Price(Money price)
        {
            this.price = price;
        }

        public Price(decimal amount, string currency)
        {
            price = new Money(amount, currency);
        }
...........
...........
}

..........
// In DbContext configuration  for enclosing entity (Product)

b.OwnsOne(prod => prod.Price, o =>
{
 // Read-only properties are not mapped by convention.
 // For decimal in SqlServer you should explicitly specify
 // the column type to avoid warning.
 o.Property(price => price!.Amount).HasColumnType("decimal(18,2)");
 o.Property(price => price!.Currency);
})