JsonSerializer does not support parsing Dictionary<TKey, TValue>

[pranavkm]

Runtime version: 3.0.0-preview4-27513-05

Consider:

var content = "{ \"key\": \"value\" }";
var result = JsonSerializer.Parse(content, typeof(Dictionary<string, string>));

This results in the following exception:

Unhandled Exception: System.NullReferenceException: Object reference not set to an instance of an object.
   at System.Text.Json.Serialization.JsonSerializer.HandleStartObject(JsonSerializerOptions options, ReadStack& state)
   at System.Text.Json.Serialization.JsonSerializer.ReadCore(JsonSerializerOptions options, Utf8JsonReader& reader, ReadStack& state)
   at System.Text.Json.Serialization.JsonSerializer.ReadCore(Type returnType, JsonSerializerOptions options, Utf8JsonReader& reader)
   at System.Text.Json.Serialization.JsonSerializer.ParseCore(String json, Type returnType, JsonSerializerOptions options)
   at System.Text.Json.Serialization.JsonSerializer.Parse(String json, Type returnType, JsonSerializerOptions options)

[ahsonkhan]

Dictionary is not currently supported with the WIP JsonSerializer. See https://github.com/dotnet/corefx/issues/34372

[analogrelay]

For the initial version to unblock ASP.NET, Dictionary<string, [some concrete type]> is sufficient.

[layomia]

Working on this now.

[layomia]

We have added support for primitives: Dictionary<string, TPrimitiveType>.
It also includes support for IDictionary<string, TPrimitiveType> and IReadOnlyDictionary<string, TPrimitiveType> where an instance of Dictionary<string, TPrimitiveType> is created.

Support for non-primitives is being tracked here: https://github.com/dotnet/corefx/issues/37077.