How to pretty print using System.Text.Json for unknown object

Question

Using System.Text.Json i can pretty print json using serialization option.

var options = new JsonSerializerOptions{ WriteIndented = true };
jsonString = JsonSerializer.Serialize(typeToSerialize, options);

However, I have string JSON and don't know the concrete type. Ho do I pretty-print JSON string?

My old code was using Newtonsoft and I could do it without serialize/deserialize

public static string JsonPrettify(this string json)
{
    if (string.IsNullOrEmpty(json))
    {
        return json;
    }

    using (var stringReader = new StringReader(json))
    using (var stringWriter = new StringWriter())
    {
        var jsonReader = new JsonTextReader(stringReader);
        var jsonWriter = new JsonTextWriter(stringWriter) { Formatting = Formatting.Indented };
        jsonWriter.WriteToken(jsonReader);
        return stringWriter.ToString();
    }
}

There's no built-in API to copy from a `Utf8JsonReader` to a `Utf8JsonWriter` so parsing to `JsonDocument` and reserializing looks to be the way to go. See [How to pretty-print (format) System.Text.JsonElement to a string](https://stackoverflow.com/q/61598778/3744182). — dbc, Jan 08 '21 at 01:14

dlumpp · Answer 1 · 2022-01-22T00:27:55.020

54

This works:

using System.Text.Json;
public static string JsonPrettify(this string json)
{
    using var jDoc = JsonDocument.Parse(json);
    return JsonSerializer.Serialize(jDoc, new JsonSerializerOptions { WriteIndented = true });
}

edited Jan 22 '22 at 00:27

answered Jun 10 '21 at 20:51

dlumpp

891
8
14

3

`JsonDocument` is `IDisposable`, and must be disposed in order to return pooled memory to the memory pool for reuse. – dbc Jan 20 '22 at 21:31
1

You're right, @dbc. I added a using. Good catch. – dlumpp Jan 22 '22 at 00:28
This doesn't work. ObjectDisposedException: Cannot access a disposed object. Object name: 'JsonDocument'. – HamsterWithPitchfork Aug 24 '22 at 12:24

score 0 · Answer 2 · answered Jul 05 '23 at 23:37

This works :


    private static string PrettifyJson(string jsonString)
    {
        using (JsonDocument jsonDocument = JsonDocument.Parse(jsonString)){
            // Convert the JsonDocument back to a pretty-printed JSON string
            string prettifiedJson = 
            System.Text.Json.JsonSerializer.Serialize(jsonDocument.RootElement, new 
                JsonSerializerOptions
                {
                    WriteIndented = true
                });
            return prettifiedJson;
        }
    }

score 0 · Answer 3 · answered Aug 31 '23 at 11:00

You can acheive it with Newtonsoft.Json JToken class. Here is the code.

using Newtonsoft.Json;
using Newtonsoft.Json.Linq;

public static string JsonPrettify(this string json)
{
    if (string.IsNullOrEmpty(json))
    {
        return json;
    }
    return JToken.Parse(json).ToString(Formatting.Indented);
}

How to pretty print using System.Text.Json for unknown object

3 Answers3

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