using Newtonsoft.Json;

​

using System.Collections.Generic;

using System.Text;

using System.IO;

​

// https://stackoverflow.com/questions/44787652/serialize-as-ndjson-using-json-net#44787652

​

using System.Linq;

using Console = System.Console;

using Environment = System.Environment;

using StringComparison = System.StringComparison;

​

    class TestClass

    {

        public static void Test()

        {

            // Include some newline and carriage return characters in string literals to make sure they're escaped.

​

            Test(Enumerable.Range(0, 4).Select(i => new { Value = "Hello \n" + i.ToString() }));

​

            Test(Enumerable.Range(0, 4).Select(i => Newtonsoft.Json.Linq.JObject.FromObject(new { Value = "Hello " + i.ToString(), NewLine = Environment.NewLine })));

​

            Console.WriteLine("Done");

        }

​

        static void Test<T>(IEnumerable<T> items)

        {

            Console.WriteLine(string.Format("Testing items of type {0}", typeof(T)));

​

            var sb = new StringBuilder();

            using (var textWriter = new StringWriter(sb))

            {

                JsonExtensions.ToNewlineDelimitedJson(textWriter, items);

            }

​

            var json = sb.ToString();

            Console.WriteLine(json);

​

            var newItems = JsonExtensions.FromNewlineDelimitedJson<T>(new StringReader(json)).ToList();

​

            Assert.IsTrue(newItems.Count == items.Count());

            Assert.IsTrue(newItems.Count == json.CountSubstrings("\n"));

​

            Console.WriteLine("Serialized JSON has the correct count of items and lines: {0}", newItems.Count);

        }

    }

​

    public static partial class JsonExtensions

    {

        public static void ToNewlineDelimitedJson<T>(Stream stream, IEnumerable<T> items)

        {

            // Let caller dispose the underlying stream 

            using (var textWriter = new StreamWriter(stream, new UTF8Encoding(false, true), 1024, true))

            {

                ToNewlineDelimitedJson(textWriter, items);

            }

        }

​

        public static void ToNewlineDelimitedJson<T>(TextWriter textWriter, IEnumerable<T> items)

        {

            var serializer = JsonSerializer.CreateDefault();

​

            foreach (var item in items)

            {

                // Formatting.None is the default; I set it here for clarity.

                using (var writer = new JsonTextWriter(textWriter) { Formatting = Formatting.None, CloseOutput = false })

                {

                    serializer.Serialize(writer, item);

                }

                // http://specs.okfnlabs.org/ndjson/

                // Each JSON text MUST conform to the [RFC7159] standard and MUST be written to the stream followed by the newline character \n (0x0A). 

                // The newline charater MAY be preceeded by a carriage return \r (0x0D). The JSON texts MUST NOT contain newlines or carriage returns.

                textWriter.Write("\n");

            }

        }

    }

​

    public static partial class JsonExtensions

    {

        public static IEnumerable<T> FromNewlineDelimitedJson<T>(TextReader reader)

        {

            using (var jsonReader = new JsonTextReader(reader) { CloseInput = false, SupportMultipleContent = true })

            {

                var serializer = JsonSerializer.CreateDefault();

​

                while (jsonReader.Read())

                {

                    if (jsonReader.TokenType == JsonToken.Comment)

                        continue;

                    yield return serializer.Deserialize<T>(jsonReader);

                }

            }

        }

    }

​

    public class AssertionFailedException : System.Exception

    {

        public AssertionFailedException() : base() { }

​

        public AssertionFailedException(string s) : base(s) { }

    }

​

    public static class Assert

    {

        public static void IsTrue(bool value)

        {

            if (value == false)

                throw new AssertionFailedException("failed");

        }

    }

​

    public static class TextExtensions

    {

        // https://stackoverflow.com/questions/541954/how-would-you-count-occurrences-of-a-string-within-a-string/11773674#11773674

        public static int CountSubstrings(this string source, string substring)

        {

            int count = 0, n = 0;

            if(substring != "")

            {

                while ((n = source.IndexOf(substring, n, StringComparison.InvariantCulture)) != -1)

                {

                    n += substring.Length;

                    ++count;

                }

            }

            return count;

        }

    }

    public class Program

    {

        public static void Main()

        {

            Console.WriteLine("Environment version: " + Environment.Version);

            Console.WriteLine("Json.NET version: " + typeof(JsonSerializer).Assembly.FullName);

            Console.WriteLine("");

            TestClass.Test();

        }

    }

​