[Discussion]: Breaking changes to Microsoft.JSInterop

[pranavkm]

In 3.0-preview6, we're migrating Microsoft.JSInterop to use the System.Text.Json based serializer. As part of this transition, there are several breaking changes to the JSInterop library:

• The helper type Microsoft.JSInterop.Json is being removed. Users may use a JSON serializer of their choice. We recommend using the System.Text.Json-based serializer since Blazor already references it. Here's the code change required to migrate to use System.Text.Json:

// Before
string value = Json.Serialize(...);
MyPoco poco = Json.Deserialize<MyPoco>("...");

// After
using System.Text.Json.Serialization;
...

string value = JsonSerializer.ToString(...);
MyPoco poco = JsonSerializer.Parse<MyPoco>("...");

• DotNetObjectRef is replaced by a generic DotNetObjectRef<T> that is required for both sending and receiving a managed object reference when doing interop with the browser

// Before
IJSRuntime.InvokeAsync("SomeJSMethod", new DotNetObjectRef(someObject));

[JSInvokable]
public static Task SomeDotNetMethod(MyObject myObject)
{
    ...
}

// After
IJSRuntime.InvokeAsync("SomeMethod", DotNetObjectRef.Create(someObject));

[JSInvokable]
public static Task SomeDotNetMethod(DotNetObjectRef<MyObject> myObject)
{
    ...
}

• Microsoft.JSInterop will use System.Text.Json to marshal interop data. To customize serialization, you may use serialization primitives such as JsonPropertyNameAttribute, JsonIgnoreAttribute etc.

• IJSRuntime.UntrackObjectRef(DotNetObjectRef); has been removed. To stop tracking an object reference, dispose the DotNetObjectRef<T> instance either on the server or the client.

[Joelius300]

I switched from the System.Text.Json-based serializer back to json.net following these ms-docs. I'm using a server-side blazor project (preview6) and called AddNewtonsoftJson on the IMvcBuilder I got back from services.AddRazorPages() in the ConfigureServices method.

The problem is that it still uses the System.Text.Json-based serializer when invoking javascript using IJSRuntime.InvokeAsync. I have already opened a SO question for this issue.

Is the way I change the serializer not correct?
What do I have to do for IJSRuntime to use json.net?