(Native AOT) No parameterless constructor defined for type

[PaddiM8]

When compiling to native AOT, I get the following: Unhandled Exception: System.MissingMethodException: No parameterless constructor defined for type 'MyClass'.

   at System.ActivatorImplementation.CreateInstance(Type, Boolean) + 0x203
   at System.Reflection.Runtime.General.ReflectionCoreCallbacksImplementation.ActivatorCreateInstance(Type, Boolean) + 0x2b
   at System.Activator.CreateInstance(Type type, Boolean nonPublic) + 0x45
   at System.Activator.CreateInstance(Type type) + 0x1f
   at SQLite.SQLiteCommand.<ExecuteDeferredQuery>d__12`1.MoveNext() + 0x6e6
   at System.Collections.Generic.List`1..ctor(IEnumerable`1) + 0x1fb
   at System.Linq.Enumerable.ToList[TSource](IEnumerable`1) + 0x81
   at SQLite.SQLiteCommand.ExecuteQuery[T]() + 0xb0
   at SQLite.SQLiteConnection.Query[T](String, Object[]) + 0x59

I didn't do anything fancy, just created a table, so should be easy to reproduce.

[cricketthomas]

@PaddiM8 did you figure out a work around for this?

[PaddiM8]

Unfortunately not.

[cricketthomas]

I am going to be looking into Microsoft.Data.Sqlite as an alternative, maybe it can work for your situation: https://learn.microsoft.com/en-us/windows/apps/develop/data-access/sqlite-data-access

They've added AOT support:
https://devblogs.microsoft.com/dotnet/announcing-ef8-rc1/
dotnet/efcore#29725

[PaddiM8]

Ohh finally. That's what I've been using with Ready-to-Run. Thanks!

[jonasnordlund]

This looks related to NativeAOT specifically with COM. I think there's part been work here for .NET 8 but I'm not sure if that will automatically solve this? Otherwise, maybe a developer might take a look at this: https://stackoverflow.com/questions/76507803/c-sharp-net-core-native-aot-with-reflection-activator-createinstance

As for the above suggestion to use Microsoft.Data.Sqlite, please note that EF Core 8 seems to have missed the target to introduce experimental NativeAOT support but that the underlying Microsoft.Data.Sqlite does support it. So, as long as it's good enough to have "only" the core library and not go full EF Core, you're good to go.