Serialize as NDJSON using Json.NET
As Json.NET does not currently have a built-in method to serialize a collection to NDJSON, the simplest answer would be to write to a single TextWriter
using a separate JsonTextWriter
for each line, setting CloseOutput = false
for each:
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);
}
// https://web.archive.org/web/20180513150745/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");
}
}
}
Sample fiddle.
Since the individual NDJSON lines are likely to be short but the number of lines might be large, this answer suggests a streaming solution to avoid the necessity of allocating a single string larger than 85kb. As explained in Newtonsoft Json.NET Performance Tips, such large strings end up on the large object heap and may subsequently degrade application performance.