在中间件中序列化对JSON的响应的最佳方法是什么？

Question

Is there a canonical way to leverage the configured JsonOutputFormatter inside ASP.NET middleware? Or, more generically, is there a better way to serialize the response to JSON than explicitly calling JsonConvert.SerializeObject in my middleware?

Currently, I have the following code:

public static void HandleHealthRequests(this IApplicationBuilder app)
{
    app.Map(new PathString("/health"), builder =>
    {
        builder.Run(async context =>
        {
            string response = JsonConvert.SerializeObject(new { DateTime.UtcNow, Version = _version });
            context.Response.StatusCode = StatusCodes.Status200OK;
            context.Response.ContentType = "application/json";
            context.Response.ContentLength = response.Length;
            await context.Response.WriteAsync(response);
        });
    });
}

This works fine, but calling JsonConvert.SerializeObject directly and manipulating the Response directly doesn't feel right.

I looked at resolving the JsonOutputFormatter to leverage it directly but it requires an OutputFormatterContext which looks too complicated to set up. Additionally, I also tried just leveraging JsonOutputFormatter.SerializerSettings but found it to be null on app startup so my code was throwing when the process started.

Answer 1

I have a similiar problem, i just want to use the same configuration for all my json responses regardless they are inside a middleware or a filter or controller... with the new versions of .net core (at least with Microsoft.AspNetCore.Mvc.Formatters.Json 1.1.2 ) i use the WriteObject(TextWriter writer, object value) method inside the formatter, i resolve the JsonOutputFormatter with dependency injection inside my middleware or filter and use that WriteObject method for serialization.

var stringWriter = new StringWriter(CultureInfo.InvariantCulture);
jsonOutputFormatter.WriteObject(stringWriter, value);
var responseBody = stringWriter.ToString();