JsonDocument type property and InMemoryDatabase provider

Notice: probably it is more InMemoryDatabase provider issue, but it is related to Npgsql driver.

Steps to reproduce

If you have free form json field something like

public JsonDocument ProviderData { get; set; }

It works fine at runtime, as Npgsql driver somehow handles it. Now if I wish to unit test this with:

 context = new MyDbContext(new DbContextOptionsBuilder<MyDbContext>()
                .UseInMemoryDatabase("My")
                .Options);

It fails with: No suitable constructor found for entity type ‘JsonDocument’.

The issue

I can not unit test models that are valid in Npgsql with InMemoryDatabase.

As a workaround, I would be fine to ignore that property in unit tests or augument DbContext in unit tests to avoid this problem, but currently have no ideas how.

Full exception trace:

System.InvalidOperationException : No suitable constructor found for entity type 'JsonDocument'. The following constructors had parameters that could not be bound to properties of the entity type: cannot bind 'utf8Json', 'parsedData', 'extraRentedBytes', 'isDisposable' in 'JsonDocument(ReadOnlyMemory<byte> utf8Json, MetadataDb parsedData, byte[] extraRentedBytes, bool isDisposable)'.
   at Microsoft.EntityFrameworkCore.Metadata.Conventions.ConstructorBindingConvention.ProcessModelFinalized(IConventionModelBuilder modelBuilder, IConventionContext`1 context)
   at Microsoft.EntityFrameworkCore.Metadata.Conventions.Internal.ConventionDispatcher.ImmediateConventionScope.OnModelFinalized(IConventionModelBuilder modelBuilder)
   at Microsoft.EntityFrameworkCore.Metadata.Conventions.Internal.ConventionDispatcher.OnModelFinalized(IConventionModelBuilder modelBuilder)
   at Microsoft.EntityFrameworkCore.Metadata.Internal.Model.FinalizeModel()
   at Microsoft.EntityFrameworkCore.ModelBuilder.FinalizeModel()
   at Microsoft.EntityFrameworkCore.Infrastructure.ModelSource.CreateModel(DbContext context, IConventionSetBuilder conventionSetBuilder)
   at Microsoft.EntityFrameworkCore.Infrastructure.ModelSource.GetModel(DbContext context, IConventionSetBuilder conventionSetBuilder)
   at Microsoft.EntityFrameworkCore.Internal.DbContextServices.CreateModel()
   at Microsoft.EntityFrameworkCore.Internal.DbContextServices.get_Model()
   at Microsoft.EntityFrameworkCore.Infrastructure.EntityFrameworkServicesBuilder.<>c.<TryAddCoreServices>b__7_3(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 singletonCallSite, 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 singletonCallSite, 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__DisplayClass1_0.<RealizeService>b__0(ServiceProviderEngineScope scope)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.ServiceProviderEngine.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_InternalServiceProvider()
   at Microsoft.EntityFrameworkCore.DbContext.get_DbContextDependencies()
   at Microsoft.EntityFrameworkCore.DbContext.EntryWithoutDetectChanges[TEntity](TEntity entity)
   at Microsoft.EntityFrameworkCore.DbContext.SetEntityState[TEntity](TEntity entity, EntityState entityState)
   at Microsoft.EntityFrameworkCore.DbContext.Add[TEntity](TEntity entity)
   at Microsoft.EntityFrameworkCore.Internal.InternalDbSet`1.Add(TEntity entity)
   at Api.Test.Tests.Setup() in C:\work\api\test\Api.Test

Further technical details

Npgsql version: 3.1.2

[dziedrius]

As usually happens, five minutes after submitting issue you come up with solution 😃

I was able to workaround the issue by extending DbContext class in unit tests:

 public class UnitTestMyDbContext : MyDbContext
    {
        public UnitTestMyDbContext(DbContextOptions options) : base(options)
        {
        }

        protected override void OnModelCreating(ModelBuilder modelBuilder)
        {
            modelBuilder.Entity<MyEntity>().Property(p => p.SomeWellDefinedJsonProperty)
                .HasConversion(
                    v => JsonConvert.SerializeObject(v),
                    v => JsonConvert.DeserializeObject<WellDefinedJsonProperty>(v));
       
            modelBuilder.Entity<MyEntity>().Property(p => p.ProviderData)
                .HasConversion(
                    v => JsonDocumentToString(v),
                    v => JsonDocument.Parse(v, new JsonDocumentOptions()));      
        }

        private static string JsonDocumentToString(JsonDocument document)
        {
            using (var stream = new MemoryStream())
            {
                var writer = new Utf8JsonWriter(stream, new JsonWriterOptions {Indented = true});
                document.WriteTo(writer);
                writer.Flush();
                return Encoding.UTF8.GetString(stream.ToArray());
            }
        }
    }

It could be useful addition to documentation.

[rahul-s-bhatt]

Hi @dziedrius thank you and sorry for troubling you. But I have fixed that by adding :

modelbuidler.Ignore<JsonDocument>

Thank you once again 👍