Formatting DateTime in ASP.NET Core 3.0 using System.Text.Json

Question

I am migrating a web API from .NET Core 2.2 to 3.0 and want to use the new System.Text.Json. When using Newtonsoft I was able to format Date

Answer 1

Migrating to Core 3 I had to replace System.Text.Json to use Newtonsoft again by :

services.AddControllers().AddNewtonsoftJson();

But I was having same issue with UTC dates in an Angular app and I had to add this to get dates in UTC:

services.AddControllers().AddNewtonsoftJson(
       options => options.SerializerSettings.DateTimeZoneHandling = DateTimeZoneHandling.Utc);

In your case you should be able to do this:

services.AddControllers().AddNewtonsoftJson(options =>
    {
        options.SerializerSettings.DateTimeZoneHandling = Newtonsoft.Json.DateTimeZoneHandling.Utc;
        options.SerializerSettings.DateFormatString = "yyyy'-'MM'-'dd'T'HH':'mm':'ssZ";
    });

It works and I hope it helps...

Answer 2

Solved with a custom formatter. Thank you Panagiotis for the suggestion.

public class DateTimeConverter : JsonConverter<DateTime>
{
    public override DateTime Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
    {
        Debug.Assert(typeToConvert == typeof(DateTime));
        return DateTime.Parse(reader.GetString());
    }

    public override void Write(Utf8JsonWriter writer, DateTime value, JsonSerializerOptions options)
    {
        writer.WriteStringValue(value.ToUniversalTime().ToString("yyyy'-'MM'-'dd'T'HH':'mm':'ssZ"));
    }
}


// in the ConfigureServices()
services.AddControllers()
    .AddJsonOptions(options =>
     {
         options.JsonSerializerOptions.Converters.Add(new DateTimeConverter());
     });