How to set json serializer settings in asp.net core 3?

Question

json serializer settings for legacy asp.net core applications were set by adding AddMvc().AddJsonOptions(), but I don't use AddMvc() in asp.net core 3. So how can I set global json serialization settings?

Answer 1

AddMvc returns an IMvcBuilder implementation, which has a corresponding AddJsonOptions extension method. The new-style methods AddControllers, AddControllersWithViews, and AddRazorPages also return an IMvcBuilder implementation. Chain with these in the same way you would chain with AddMvc:

services.AddControllers()
    .AddJsonOptions(options =>
    {
        // ...
    });

Note that options here is no longer for Json.NET, but for the newer System.Text.Json APIs. If you still want to use Json.NET, see tymtam's answer

Answer 2

Option A. AddControllers

This is still MVC, and requires Microsoft.AspNetCore.Mvc.NewtonsoftJson nuget package, but you said you use AddControllers.

From Add Newtonsoft.Json-based JSON format support

services.AddControllers().AddNewtonsoftJson(options =>
{
    // Use the default property (Pascal) casing
    options.SerializerSettings.ContractResolver = new DefaultContractResolver();

    // Configure a custom converter
    options.SerializerOptions.Converters.Add(new MyCustomJsonConverter());
});

---

Option B. DefaultSettings

JsonConvert.DefaultSettings = () => new JsonSerializerSettings (...)

JsonConvert.DefaultSettings Property

Gets or sets a function that creates default JsonSerializerSettings. Default settings are automatically used by serialization methods on JsonConvert, and ToObject () and FromObject(Object) on JToken. To serialize without using any default settings create a JsonSerializer with Create().

Answer 3

Adding Newtonsoft is not necessary, quite a problems with adding Newtonsoft compatibility packages on .Net Core 3.0 project.

See also https://github.com/aspnet/AspNetCore/issues/13564

Of course, one would celebrate property naming PascalCase, NA at the moment... So null for PropertyNamingPolicy means PascalCase, which is obviously not very good.

// Pascal casing
services.AddControllersWithViews().
        AddJsonOptions(options =>
        {
            options.JsonSerializerOptions.PropertyNameCaseInsensitive = true;
            options.JsonSerializerOptions.PropertyNamingPolicy = null;
        });

Answer 4

You can try System.Text.Json, the newly released Json nuget package converter. Startup.cs as below You can write this code inside the configirationSetting method.

 services.AddControllers()
     .AddJsonOptions(options =>
      {
          options.JsonSerializerOptions.PropertyNameCaseInsensitive = true;
          options.JsonSerializerOptions.PropertyNamingPolicy = null;
          options.JsonSerializerOptions.Converters.Add (new JsonStringEnumConverter ());
      });  

Answer 5

In .net6 add this code after .AddControllers() in program.cs file:

builder.Services.AddControllers().AddJsonOptions(options =>
{
    options.JsonSerializerOptions.PropertyNamingPolicy = null;
});

Answer 6

1.install NuGet : Microsoft.AspNetCore.Mvc.NewtonsoftJson or

   <ItemGroup>
        <PackageReference Include="Microsoft.AspNetCore.Mvc.NewtonsoftJson" Version="3.1.2" />
    </ItemGroup>

2. Add Startup.cs :

   public void ConfigureServices(IServiceCollection services)
     {
         //JSON Serializer
         services.AddControllers().AddNewtonsoftJson(options =>
           {
            options.SerializerSettings.ReferenceLoopHandling = 
               Newtonsoft.Json.ReferenceLoopHandling.Ignore;
           });
    }