Support System.Text.Json

[petrsvihlik]

Blockers

Deserialization of interface types is not supported. - Polymorphic deserialization will be supported in .NET 5

• JsonSerializer polymorphic serialization and deserialization support dotnet/runtime#30083

Workaround

• https://github.com/lwardzala/Json.Abstraction

Motivation

• improve performance in high-throughput scenarios
• reduce the number of non-framework dependencies in the default implementation
• let users implement decide what deserializer to use

Proposed solution

• Use System.Text.Json for serialization
• Adjust code & docs so that it's clear how to implement a serializer of one's choice (some people might want to go e.g. with superfast Utf8Json)

Additional context

• How to migrate from Newtonsoft.Json to System.Text.Json
  
• improvements: https://devblogs.microsoft.com/dotnet/announcing-net-5-0-preview-3/

Benchmarks

• https://michaelscodingspot.com/the-battle-of-c-to-json-serializers-in-net-core-3/
• https://dotnetcoretutorials.com/2020/01/25/what-those-benchmarks-of-system-text-json-dont-mention/
• https://devblogs.microsoft.com/dotnet/try-the-new-system-text-json-apis/#user-content-performance
• https://github.com/dotnet/performance/tree/3b1f70c310b3f852d7084e3b10c76aa364573106/src/benchmarks/micro
• https://aloiskraus.wordpress.com/2019/09/29/net-serialization-benchmark-2019-roundup/
• https://medium.com/@samichkhachkhi/system-text-json-vs-newtonsoft-json-d01935068143

[tomasjurasek]

I found the extension library for System.Text.Json which supports interface deserialization - https://github.com/dahomey-technologies/Dahomey.Json

[petrsvihlik]

Some good news:

• https://devblogs.microsoft.com/dotnet/whats-next-for-system-text-json/

They plan to extend polymorphic serialization and deserialization: dotnet/runtime#45189

So this feature might become unblocked after .NET 6.

[qpooqp]

Hello.
Just want to ask if there will be any progress on this issue now that System.Text.Json got lots of improvements.

I have models generated by the model generator.
My main problem is interface types in the models. For example i have model with property of type Kontent.Ai.Delivery.Abstractions.ITaxonomyTerm.
I need concrete type for deserialization and i don't like the idea that i should create my own types based on the interfaces. That would mean that i need to keep them up to date with the interfaces when they changes and this is additional work. It would be nice to have some concrete types available.

I was thinking about source generator that would create the concrete types based on the interfaces, but i would prefer to have some "official" solution for me to be able to serialize and deserialize the models.