Cosmos: Unable to use value conversion for primitive collection

[Drewfyre]

Bug description

Issue:
When trying to convert from a Dictionary<(Guid, Guid), string> into a flattened List<(string, string, string)> I get the following error:

The 'List<ValueTuple<string, string, string>>' property 'Root.Matrix' could not be mapped because the database provider does not support this type. Consider converting the property value to a type supported by the database using a value converter.

I thought the issue was that I am using a primitive collection and EF would expect and actual reference object so I did try to replace the Tuple<string, string, string> with an actual class with 3 string properties, i.e.:

public class MatrixEntry(string X, string Y, string Value);

But this did not solve the error either.

Your code

using Microsoft.EntityFrameworkCore;
using Microsoft.EntityFrameworkCore.Metadata.Builders;

var endpointUri = "https://localhost:8081";
var primaryKey = "";
var database = "testDb";

var options = new DbContextOptionsBuilder().UseCosmos(endpointUri, primaryKey, database).Options;
var dbContext = new AppDbContext(options);

var root = new Root();
root.Matrix.Add(Guid.CreateVersion7(), Guid.CreateVersion7(), "100");

dbContext.Roots.Add(root);
dbContext.SaveChanges();

public class Root
{
    public Guid Id { get; set; } = Guid.CreateVersion7();
    public string PartitionKey = "Root";
    public GuidMatrix Matrix { get; set; } = [];

}

public class GuidMatrix : Dictionary<(Guid, Guid), string>
{
    public void Add(Guid x, Guid y, string value)
    {
        this[(x, y)] = value;
        this[(y, x)] = value;
    }
}

public class AppDbContext(DbContextOptions options) : DbContext(options)
{
    public DbSet<Root> Roots { get; set; }

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        modelBuilder.HasDefaultContainer("public");
        modelBuilder.ApplyConfigurationsFromAssembly(typeof(AppDbContext).Assembly);
        base.OnModelCreating(modelBuilder);
    }}

public class RootConfiguration : IEntityTypeConfiguration<Root>
{
    public void Configure(EntityTypeBuilder<Root> builder)
    {
        builder.HasKey(x => x.Id);
        builder.HasPartitionKey(x => x.PartitionKey);
        builder.Property(x => x.Matrix)
            .HasConversion(x => FlattenMatrix(x), y => ReconstructMatrix(y));
    }

    private static List<(string, string, string)> FlattenMatrix(GuidMatrix matrix)
    {
        var result = new List<(string, string, string)>();
        var processedPairs = new List<(Guid, Guid)>();

        foreach (var kv in matrix)
        {
            var x = kv.Key.Item1;
            var y = kv.Key.Item2;

            if (processedPairs.Contains((x, y)) || processedPairs.Contains((y, x))) continue;

            result.Add((x.ToString(), y.ToString(), kv.Value));
            processedPairs.Add((x, y));
        }

        return result;
    }

    private static GuidMatrix ReconstructMatrix(List<(string, string, string)> list)
    {
        var matrix = new GuidMatrix();

        foreach (var (x, y, value) in list)
        {
            matrix.Add((Guid.Parse(x), Guid.Parse(y)), value);
        }

        return matrix;
    }
}

Stack traces

"C:\Program Files\JetBrains\JetBrains Rider 2021.3.2\plugins\dpa\DotFiles\JetBrains.DPA.Runner.exe" --handle=18444 --backend-pid=10652 --etw-collect-flags=67108622 --detach-event-name=dpa.detach.10652.23 --refresh-interval=1 -- C:/Users/ny46864/dev/SampeApp/bin/Debug/net9.0/SampeApp.exe
Unhandled exception. System.InvalidOperationException: The 'List<ValueTuple<string, string, string>>' property 'Root.Matrix' could not be mapped because the database provider does not support this type. Consider converting the property value to a type supported by the database using a value converter. See https://aka.ms/efcore-docs-value-converters for more information. Alternately, exclude the property from the model using the '[NotMapped]' attribute or by using 'EntityTypeBuilder.Ignore' in 'OnModelCreating'.
   at Microsoft.EntityFrameworkCore.Infrastructure.ModelValidator.ThrowPropertyNotMappedException(String propertyType, IConventionTypeBase typeBase, IConventionProperty unmappedProperty)
   at Microsoft.EntityFrameworkCore.Infrastructure.ModelValidator.<ValidatePropertyMapping>g__Validate|7_0(IConventionTypeBase typeBase, <>c__DisplayClass7_0&)
   at Microsoft.EntityFrameworkCore.Infrastructure.ModelValidator.ValidatePropertyMapping(IModel model, IDiagnosticsLogger`1 logger)
   at Microsoft.EntityFrameworkCore.Cosmos.Infrastructure.Internal.CosmosModelValidator.ValidatePropertyMapping(IModel model, IDiagnosticsLogger`1 logger)
   at Microsoft.EntityFrameworkCore.Infrastructure.ModelValidator.Validate(IModel model, IDiagnosticsLogger`1 logger)
   at Microsoft.EntityFrameworkCore.Cosmos.Infrastructure.Internal.CosmosModelValidator.Validate(IModel model, IDiagnosticsLogger`1 logger)
   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(ServiceIdentifier serviceIdentifier, 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(IInfrastructure`1 accessor, Type serviceType)
   at Microsoft.EntityFrameworkCore.Infrastructure.Internal.InfrastructureExtensions.GetService[TService](IInfrastructure`1 accessor)
   at Microsoft.EntityFrameworkCore.Infrastructure.AccessorExtensions.GetService[TService](IInfrastructure`1 accessor)
   at Microsoft.EntityFrameworkCore.Infrastructure.DatabaseFacade.get_Dependencies()
   at Microsoft.EntityFrameworkCore.Infrastructure.DatabaseFacade.EnsureDeletedAsync(CancellationToken cancellationToken)
   at Program.<Main>$(String[] args) in C:\Users\ny46864\dev\SampeApp\Program.cs:line 14
   at Program.<Main>(String[] args)

Verbose output

EF Core version

9.0.0

Database provider

Microsoft.EntityFrameworkCore.Cosmos

Target framework

.NET 9.0

Operating system

Windows 10

IDE

No response

[AndriySvyryd]

This looks like a case that would be covered by #25343