Json.Net fails to serialize to a stream, but works just fine serializing to a string

Question

Internally, JsonConvert.SerializeObject(obj, Formatting.Indented) boils down to

JsonSerializer jsonSerializer = JsonSerializer.Create(null);
StringWriter stringWriter = new StringWriter(new StringBuilder(256), (IFormatProvider) CultureInfo.InvariantCulture);
using (JsonTextWriter jsonTextWriter = new JsonTextWriter((TextWriter) stringWriter))
{
  jsonTextWriter.Formatting = formatting;
  jsonSerializer.Serialize((JsonWriter) jsonTextWriter, value);
}
return stringWriter.ToString();

This works just fine. However, if I do the following:

string json;

JsonSerializer jsonSerializer = JsonSerializer.Create();

using (var stream = new MemoryStream())
using (var streamWriter = new StreamWriter(stream, Encoding.UTF8))
using (var jsonWriter = new JsonTextWriter(streamWriter))
{
    serializer.Serialize(jsonWriter, cmd);

    stream.Position = 0;
    using (var reader = new StreamReader(stream))
    {
        json = reader.ReadToEnd();
    }
}

Then the value of json is "". Can anyone point me to my mistake?

Answer 1

The problem is that you haven't flushed the streamWriter after writing:

serializer.Serialize(jsonWriter, cmd);
streamWriter.Flush();
stream.Position = 0;

Alternatively, why not just use a StringWriter to start with?

using (var writer = new StringWriter())
{
    using (var jsonWriter = new JsonTextWriter(writer))
    {
        serializer.Serialize(jsonWriter, cmd);
        Console.WriteLine(writer.ToString());
    }
}