Does ToJson not supported? Getting exception

[pantonis]

Steps to reproduce

public class OrderContext : DbContext
    {
        public DbSet<Order> Orders { get; set; }

        protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
        {
            var connectionString = "";
            optionsBuilder.UseMySql(ServerVersion.AutoDetect(connectionString), options =>
            {
                options.EnableRetryOnFailure();
            });
        }

        protected override void OnModelCreating(ModelBuilder modelBuilder)
        {
            modelBuilder.Entity<Order>().OwnsOne(
                                                 order => order.ShippingInfo, ownedNavigationBuilder =>
                                                 {
                                                     ownedNavigationBuilder.ToJson();
                                                     ownedNavigationBuilder.OwnsMany(si => si.Shipments);
                                                     ownedNavigationBuilder.OwnsMany(si => si.Deliveries);
                                                 });
        }
    }

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

        [Required]
        public DateTime OrderDate { get; set; }

        [Required]
        public string CustomerName { get; set; }

        [Required]
        public ShippingInfo ShippingInfo { set; get; }
    }

    public class ShippingInfo
    {
        public string Address { get; set; }
        public string City { get; set; }
        public string State { get; set; }
        public string PostalCode { get; set; }

        public List<Shipment> Shipments { get; } = new();
        public List<Delivery> Deliveries { get; } = new();
    }

    public class Shipment
    {
        public string TrackingNumber { get; set; }
        public DateTime ShipDate { get; set; }
        public string Carrier { get; set; }
    }

    public class Delivery
    {
        public string ReceiverName { get; set; }
        public DateTime DeliveryDate { get; set; }
        public string Signature { get; set; }
    }

The issue

When I run Add-Migration InitialCreate I get an error

If you are seeing an exception, include the full exceptions details (message and stack trace).

Exception message: System.NullReferenceException: Object reference not set to an instance of an object.
Stack trace:
  at Microsoft.EntityFrameworkCore.Metadata.Internal.RelationalModel.CreateTableMapping(IRelationalTypeMappingSource relationalTypeMappingSource, IEntityType entityType, IEntityType mappedType, StoreObjectIdentifier mappedTable, RelationalModel databaseModel, List`1 tableMappings, Boolean includesDerivedTypes, Nullable`1 isSplitEntityTypePrincipal)
   at Microsoft.EntityFrameworkCore.Metadata.Internal.RelationalModel.AddTables(RelationalModel databaseModel, IEntityType entityType, IRelationalTypeMappingSource relationalTypeMappingSource)
   at Microsoft.EntityFrameworkCore.Metadata.Internal.RelationalModel.Create(IModel model, IRelationalAnnotationProvider relationalAnnotationProvider, IRelationalTypeMappingSource relationalTypeMappingSource, Boolean designTime)
   at Microsoft.EntityFrameworkCore.Metadata.Internal.RelationalModel.Add(IModel model, IRelationalAnnotationProvider relationalAnnotationProvider, IRelationalTypeMappingSource relationalTypeMappingSource, Boolean designTime)
   at Microsoft.EntityFrameworkCore.Infrastructure.RelationalModelRuntimeInitializer.InitializeModel(IModel model, Boolean designTime, Boolean prevalidation)
   at Microsoft.EntityFrameworkCore.Infrastructure.ModelRuntimeInitializer.Initialize(IModel model, Boolean designTime, IDiagnosticsLogger`1 validationLogger)
   at Microsoft.EntityFrameworkCore.Infrastructure.ModelSource.GetModel(DbContext context, ModelCreationDependencies modelCreationDependencies, Boolean designTime)
   at Microsoft.EntityFrameworkCore.Internal.DbContextServices.CreateModel(Boolean designTime)
   at Microsoft.EntityFrameworkCore.Internal.DbContextServices.get_Model()
   at Microsoft.EntityFrameworkCore.Infrastructure.EntityFrameworkServicesBuilder.<>c.<TryAddCoreServices>b__8_4(IServiceProvider p)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitFactory(FactoryCallSite factoryCallSite, RuntimeResolverContext context)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor`2.VisitCallSiteMain(ServiceCallSite callSite, TArgument argument)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitCache(ServiceCallSite callSite, RuntimeResolverContext context, ServiceProviderEngineScope serviceProviderEngine, RuntimeResolverLock lockType)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitScopeCache(ServiceCallSite callSite, RuntimeResolverContext context)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor`2.VisitCallSite(ServiceCallSite callSite, TArgument argument)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitConstructor(ConstructorCallSite constructorCallSite, RuntimeResolverContext context)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor`2.VisitCallSiteMain(ServiceCallSite callSite, TArgument argument)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitCache(ServiceCallSite callSite, RuntimeResolverContext context, ServiceProviderEngineScope serviceProviderEngine, RuntimeResolverLock lockType)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitScopeCache(ServiceCallSite callSite, RuntimeResolverContext context)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor`2.VisitCallSite(ServiceCallSite callSite, TArgument argument)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitConstructor(ConstructorCallSite constructorCallSite, RuntimeResolverContext context)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor`2.VisitCallSiteMain(ServiceCallSite callSite, TArgument argument)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitCache(ServiceCallSite callSite, RuntimeResolverContext context, ServiceProviderEngineScope serviceProviderEngine, RuntimeResolverLock lockType)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitScopeCache(ServiceCallSite callSite, RuntimeResolverContext context)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor`2.VisitCallSite(ServiceCallSite callSite, TArgument argument)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitConstructor(ConstructorCallSite constructorCallSite, RuntimeResolverContext context)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor`2.VisitCallSiteMain(ServiceCallSite callSite, TArgument argument)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitCache(ServiceCallSite callSite, RuntimeResolverContext context, ServiceProviderEngineScope serviceProviderEngine, RuntimeResolverLock lockType)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitScopeCache(ServiceCallSite callSite, RuntimeResolverContext context)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor`2.VisitCallSite(ServiceCallSite callSite, TArgument argument)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitConstructor(ConstructorCallSite constructorCallSite, RuntimeResolverContext context)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor`2.VisitCallSiteMain(ServiceCallSite callSite, TArgument argument)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitCache(ServiceCallSite callSite, RuntimeResolverContext context, ServiceProviderEngineScope serviceProviderEngine, RuntimeResolverLock lockType)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitScopeCache(ServiceCallSite callSite, RuntimeResolverContext context)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor`2.VisitCallSite(ServiceCallSite callSite, TArgument argument)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitConstructor(ConstructorCallSite constructorCallSite, RuntimeResolverContext context)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor`2.VisitCallSiteMain(ServiceCallSite callSite, TArgument argument)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitCache(ServiceCallSite callSite, RuntimeResolverContext context, ServiceProviderEngineScope serviceProviderEngine, RuntimeResolverLock lockType)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitScopeCache(ServiceCallSite callSite, RuntimeResolverContext context)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor`2.VisitCallSite(ServiceCallSite callSite, TArgument argument)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.Resolve(ServiceCallSite callSite, ServiceProviderEngineScope scope)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.DynamicServiceProviderEngine.<>c__DisplayClass2_0.<RealizeService>b__0(ServiceProviderEngineScope scope)
   at Microsoft.Extensions.DependencyInjection.ServiceProvider.GetService(Type serviceType, ServiceProviderEngineScope serviceProviderEngineScope)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.ServiceProviderEngineScope.GetService(Type serviceType)
   at Microsoft.Extensions.DependencyInjection.ServiceProviderServiceExtensions.GetRequiredService(IServiceProvider provider, Type serviceType)
   at Microsoft.Extensions.DependencyInjection.ServiceProviderServiceExtensions.GetRequiredService[T](IServiceProvider provider)
   at Microsoft.EntityFrameworkCore.DbContext.get_DbContextDependencies()
   at Microsoft.EntityFrameworkCore.DbContext.get_ContextServices()
   at Microsoft.EntityFrameworkCore.DbContext.get_InternalServiceProvider()
   at Microsoft.EntityFrameworkCore.DbContext.Microsoft.EntityFrameworkCore.Infrastructure.IInfrastructure<System.IServiceProvider>.get_Instance()
   at Microsoft.EntityFrameworkCore.Infrastructure.Internal.InfrastructureExtensions.GetService[TService](IInfrastructure`1 accessor)
   at Microsoft.EntityFrameworkCore.Infrastructure.AccessorExtensions.GetService[TService](IInfrastructure`1 accessor)
   at Microsoft.EntityFrameworkCore.Design.Internal.DbContextOperations.CreateContext(Func`1 factory)
   at Microsoft.EntityFrameworkCore.Design.Internal.DbContextOperations.CreateContext(String contextType)
   at Microsoft.EntityFrameworkCore.Design.Internal.MigrationsOperations.AddMigration(String name, String outputDir, String contextType, String namespace)
   at Microsoft.EntityFrameworkCore.Design.OperationExecutor.AddMigrationImpl(String name, String outputDir, String contextType, String namespace)
   at Microsoft.EntityFrameworkCore.Design.OperationExecutor.AddMigration.<>c__DisplayClass0_0.<.ctor>b__0()
   at Microsoft.EntityFrameworkCore.Design.OperationExecutor.OperationBase.<>c__DisplayClass3_0`1.<Execute>b__0()
   at Microsoft.EntityFrameworkCore.Design.OperationExecutor.OperationBase.Execute(Action action)
Object reference not set to an instance of an object.

Further technical details

MySQL version: 8.0.0 Operating system: Windows 10 Pomelo.EntityFrameworkCore.MySql version: 7.0.0 Microsoft.AspNetCore.App version: net7.0

Other details about my project setup:

[redbanana32]

I also faced the same problem

[sbalocky]

Same here ..

[yukozh]

Blocks #1746

[pantonis]

Can this be relased before 8.0 ?

[yukozh]

I'm working on upgrading Pomelo.EFCore.MySql to 8.0-preview now, and there are many failure cases that I have to handle. I know ToJson is a 7.0 feature. But I'm not sure ToJson implementation can be finished before Microsoft release .NET 8. I will consider port ToJson back to 7.0. But it will happen after I implemented ToJson in 8.0.

[pantonis]

I totally understand. thank you. Until this fixed here is a workaround I have used for anyone having the same issue

entity.Property(v => v.MyColumnClass).HasConversion(
			    v => JsonConvert.SerializeObject(v),
				v => JsonConvert.DeserializeObject<MyClass>(v), new ValueComparer<MyClass>(
					  (td1, td2) => JsonConvert.SerializeObject(td1) == JsonConvert.SerializeObject(td2),
					  td => td == null ? 0 : JsonConvert.SerializeObject(td).GetHashCode(),
					  td => JsonConvert.DeserializeObject<MyClass>(JsonConvert.SerializeObject(td))
					 )).HasColumnType("json");

which uses Newtonsoft.Json library. If you don't want to use Newtonsoft.Json replace JsonConvert.SerializeObject and JsonConvert.DeserializeObject with the library of your choice

[lauxjpn]

There is extensive JSON support in Pomelo, that does not use ToJson. For some examples, see https://github.com/PomeloFoundation/Pomelo.EntityFrameworkCore.MySql/issues/14#issuecomment-725257107 or https://github.com/PomeloFoundation/Pomelo.EntityFrameworkCore.MySql/issues/1752#issuecomment-1824090041 (you will also find other samples in the issues section).