.NET Core: Remove null fields from API JSON response

Question

On a global level in .NET Core 1.0 (all API responses), how can I configure Startup.cs so that null fields are removed/ignored in JSON responses?

Using Newtonsoft.Js

Answer 1

[.NET Core 1.0]

In Startup.cs, you can attach JsonOptions to the service collection and set various configurations, including removing null values, there:

public void ConfigureServices(IServiceCollection services)
{
     services.AddMvc()
             .AddJsonOptions(options => {
                options.SerializerSettings.NullValueHandling = NullValueHandling.Ignore;
     });
}

[.NET Core 3.1]

Instead of:

options.SerializerSettings.NullValueHandling = NullValueHandling.Ignore;

Use:

options.JsonSerializerOptions.IgnoreNullValues = true;