.NET Core: Remove null fields from API JSON response

问题

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.Json, you can apply the following attribute to a property, but I'd like to avoid having to add it to every single one:

[JsonProperty(NullValueHandling = NullValueHandling.Ignore)]
public string FieldName { get; set; }
[JsonProperty(NullValueHandling = NullValueHandling.Ignore)]
public string OtherName { get; set; }

回答1:

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;
     });
}

回答2:

This can also be done per controller in case you don't want to modify the global behavior:

public IActionResult GetSomething()
{
   var myObject = GetMyObject();
   return new JsonResult(myObject, new JsonSerializerSettings() 
   { 
       NullValueHandling = NullValueHandling.Ignore 
   });
};

回答3:

The following works for .NET Core 3.0, in Startup.cs > ConfigureServices():

services.AddMvc()
    .AddJsonOptions(options =>
    {
        options.JsonSerializerOptions.IgnoreNullValues = true;
    });

来源：https://stackoverflow.com/questions/44595027/net-core-remove-null-fields-from-api-json-response