Json Question posted in
Our archive of expertly curated questions and answers provides insights and solutions to common problems related to this popular data interchange format. From parsing and manipulating JSON data to integrating it with various programming languages and web services, our archive has got you covered. Start exploring today and take your JSON skills to the next level

Read byte[] from json using System.Text.Json

I receive dynamic JSON in my web api post request.

[HttpPost("receive")]
public async Task<IActionResult> ReceiveJson([FromBody] JsonDocument document)

One of my JSON elements is a binary array:

"attachments": [
    {
        "content": [
            255,
            216,                
            ...
            128,
            70
        ]
    }

I am unable to read that array into anything really.
I can get it as a JsonElement and see that it is ValueKind Array:

ok = attachment.TryGetProperty("content", out JsonElement attachmentContent);
string attachmentContentType = attachmentContent.ValueKind.ToString();
//gives Array

But how do I get it itto a byte[]?

Tags:

2

Answers


  1. 0

    The following code is a custom JSON converter for byte array:

    public class JsonByteArrayConverter : JsonConverter<byte[]>
{
    public override byte[] Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
    {
        if (reader.TokenType != JsonTokenType.StartArray)
        {
            throw new JsonException();
        }

        var byteArray = new List<byte>();
        while (reader.Read())
        {
            if (reader.TokenType == JsonTokenType.EndArray)
            {
                return byteArray.ToArray();
            }

            if (reader.TokenType == JsonTokenType.Number)
            {
                byteArray.Add(reader.GetByte());
            }
        }

        throw new JsonException();
    }

    public override void Write(Utf8JsonWriter writer, byte[] value, JsonSerializerOptions options)
    {
        throw new NotImplementedException();
    }
}

    As an example:

    string jsonString = "{"attachments":[{"content":[255,216,12,70]}]}";

// Deserialize the JSON string
var deserializedObject = JsonConvert.DeserializeObject<dynamic>(jsonString);

// Access the binary array and convert it to a byte array
byte[] byteArray = deserializedObject.attachments[0].content.ToObject<byte[]>();
    Login or Signup to reply.
  2. 0

    Following code retrieves byte[] from the JsonElement:

    int count;
List<byte> contentValues = new List<byte>();

using (JsonDocument document = JsonDocument.Parse(jsonString))
{
    JsonElement root = document.RootElement;
    JsonElement attachmentsElement = root.GetProperty("attachments");

    count = attachmentsElement.GetArrayLength();

    foreach (JsonElement student in attachmentsElement.EnumerateArray())
    {
        if (student.TryGetProperty("content", out JsonElement contentElement))
        {
            foreach(JsonElement ele in contentElement.EnumerateArray())
            {
                contentValues.Add(ele.GetByte());
            }
        }
    }
}

byte[] allContents = contentValues.ToArray();
    Login or Signup to reply.
Please signup or login to give your own answer.

Back To Top
Search