System.Text.Json work planned for .NET 7

[eiriktsarpalis]

This issue captures the planned work for .NET 7. This list is expected to change throughout the release cycle according to ongoing planning and discussions, with possible additions and subtractions to the scope.

Summary

For .NET 7 we are prioritizing System.Text.Json work according to the following high-level themes:

1. Extensibility: focus on features that make it easier for users/library authors to build production-quality add-ons that extend the functionality of the serializer.
2. Reliability: minimize the number of high-impact bugs in the codebase.
3. Consistency: functional convergence between reflection-based and source generated serializers. Create a specification for the serializers that highlights the semantic differences between the components.

Planned for .NET 7

Contract Model Features

• Developers can customize the JSON serialization contracts of their types #63686
• Developers can use System.Text.Json to serialize type hierarchies securely #63747
• Ensure JsonSerializer / source generator works well with required members #70945
• Implement a concept of "Required" properties #29861

Converter Features

• Support DateOnly and TimeOnly in JsonSerializer #53539
• [API Proposal]: Expose a JsonSerializerOptions.Default property #61093

Source Generation Features

• [API Proposal]: add overloads to support IAsyncEnumerable with source-gen #59268
• JsonSerializer support for JsonDocument types in source generation mode #59954

Utf8JsonWriter/Utf8JsonReader Features

• Support non-allocating view on string properties values of JSON in System.Text.Json.Utf8JsonReader #54410
  • Add Utf8JsonReader.ValueIsEscaped property #45167
• Add MaxDepth to JsonWriterOptions #44947

Misc Features

• [API Proposal]: HttpClient.PatchAsJsonAsync() #60531
• [API Proposal]: Add DeleteFromJsonAsync for HttpClient #65617
• [API Proposal]: Add a JsonEncodedText.Value property #69716

Consistency & Reliability

• Use global caching in JsonSerializerOptions #64646
• Use instance methods for SerializeHandler in source gen #61448

Planned for Future Releases

• Developers should have a more consistent experience when using System.Text.Json #63918

Contract Model Features

• Add snake_case support for System.Text.Json #782
• System.Text.Json : Consider supporting F# discriminated unions #55744
• Support modifying (rather than replacing) already-initialized properties and fields when deserializing #30258

Converter Features

• Developers should have access to System.Text.Json's default internal converters #63791
• [System.Text.Json] JsonConverter lacks ability to specify converter for items in a collection #54189
• Developers should be able to pass state to custom converters. #63795
• System.Text.Json does not fill JsonExtensionData when a property with the same name already exists or has the JsonIgnoreAttribute #68895

Source Generation Features

• Support JsonExtensionData in source generator fast path #58943
• System.Text.Json source generator fails to deserialize init-only & required properties #58770
• Add JsonContent.Create overloads that accept JsonTypeInfo. #51544

Utf8JsonWriter/Utf8JsonReader Features

• Expose line number and byte position in line as public properties on Utf8JsonReader #28482
• Consider adding Utf8JsonWriter support for writing raw property names #54005

JsonDocument/JsonNode Features

• Additional JsonNode functionality #56592
• [API Proposal]: Method to obtain an "empty" JsonDocument #59303

JSON schema validation/generation

• [System.Text.Json] Json Schemas Support #29887

Misc features

• [API Proposal]: Add a JsonEncodedText.Value property #69716

Performance Enhancements

• Source generator should share property-level custom converters #59041
• Add an analyzer that warns on single-use JsonSerializerOptions instances #65396
• Make KeyValuePair<,> support in JSON src-gen mode trim-safe #60072
• Micro-optimizations for STJ generated source #52218
• Enable SIMD for JSON API #28937

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Issue Details

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Epic tracking all planned work for System.Text.Json in .NET 7 grouped by areas of investment.

Contract model features

• Developers can customize the JSON serialization contracts of their types #63686
• Developers can use System.Text.Json to serialize type hierarchies securely #63747
• Implement a concept of "Required" properties #29861
• Support modifying (rather than replacing) already-initialized properties and fields when deserializing #30258
• Add snake_case support for System.Text.Json #782
• System.Text.Json : Consider supporting F# discriminated unions #55744

Converter features

• Support DateOnly and TimeOnly in JsonSerializer #53539

Source Generation features

• System.Text.Json source generator fails to deserialize init-only & required properties #58770
• [API Proposal]: add overloads to support IAsyncEnumerable with source-gen #59268
• JsonSerializer support for JsonDocument types in source generation mode #59954
• Add JsonContent.Create overloads that accept JsonTypeInfo. #51544

Utf8JsonWriter/Utf8JsonReader features

• Support non-allocating view on string properties values of JSON in System.Text.Json.Utf8JsonReader #54410
• Consider adding Utf8JsonWriter support for writing raw property names #54005
• Expose line number and byte position in line as public properties on Utf8JsonReader #28482
• Allow changing the newline sequence for indenting using Utf8JsonWriter #54715
• Add MaxDepth to JsonWriterOptions #44947

JsonDocument/JsonNode features

• Additional JsonNode functionality #56592
• [API Proposal]: Method to obtain an "empty" JsonDocument #59303

Documentation

• Write a specification for JsonSerializer.
• Document divergences between reflection-based and source generated serializers.

Performance Enhancements

• Enable SIMD for JSON API #28937

Author:	eiriktsarpalis
Assignees:	-
Labels:	Epic, area-System.Text.Json, Priority:1, Team:Libraries
Milestone:	7.0.0