Cimpress-MCP.DataUri

A framework to handle converting objects to and from DataUris. With built in support for handling application/json DataUris. The framework is written in compliance with RFC-2397.

Using this library

Parsing DataUris

There is built-in support for handling dataUris with the media type of application/json.

class Person
{
    public string Name { get; set; }
}

string dataUri = "data:application/json,{\"name\":\"andrew\"}";
Person andrew = DataUri.ToObject<Person>(dataUri);
Assert.Equal("andrew", andrew.Name);

Another example with a base64 encoded payload

string dataUri = "data:application/json;base64,eyJuYW1lIjoiYW5kcmV3In0=";
Person andrew = DataUri.ToObject<Person>(dataUri);
Assert.Equal("andrew", andrew.Name);

Additionally when dealing with large json payloadds the data of the uri can be compressed with the deflate or gzip algorithm.

string dataUri = "data:application/json;content-coding=deflate;base64,q1byS8xNVbJSSsxLKUotV6oFAA==";
Person andrew = DataUri.ToObject<Person>(dataUri);
Assert.Equal("andrew", andrew.Name);

Handling other media types

The rules deserializing data uris is done by the media type of the dataUri. There is a registry of known media types the and interface to deserialize them. For example to add a deserializer for image/png using Bitmap and System.Drawing.

class ImageDeserializer : IDataUriDeserializer
{
    public const string MEDIA_TYPE = "image/png";

    public object DeserializeDataUri(DataUri dataUri, Type targetType)
    {
        byte[] imageBytes = dataUri.Base64 ? Convert.FromBase64String(dataUri.Data) : Encoding.UTF8.GetBytes(dataUri.Data);

        using (MemoryStream memStream = new MemoryStream(imageBytes))
        {
            return new Bitmap(memStream);
        }
    }
}

DataUri.RegisterDataDeserializer("image/png", new ImageDeserializer());
string dataUri = "data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAoAAAAKCAYAAACNMs+9AAAAAXNSR0IArs4c6QAAAARnQU1BAACxjwv8YQUAAAAJcEhZcwAADsMAAA7DAcdvqGQAAAAWSURBVChTY6AdqP9/5T+UOQpIBQwMAB4hA1I5813pAAAAAElFTkSuQmCC";
Bitmap image = DataUri.ToObject<Bitmap>(dataUri);

Creating a DataUri from an object

By default when dataUris are created from an object the object is serialized using Newtonsoft.Json, base64 encoded, and labeled as application/json.

Person andrew = new Person()
{
    Name = "andrew"
};
var dataUri = DataUri.FromObject(andrew);
dataUri.ToString() => "data:application/json;content-coding=deflate;base64,q1byS8xNVbJSSsxLKUotV6oFAA=="

Updating FromObject

Different ObjectSerializationSettings can be provided to the FromObject method to change the behavoir. The most important part of the change is the IObjectSerializer that contains the rules for how to change an object into a byte array. For example to use gzip as an encoding algorithm:

class GZipSerializer : IObjectSerializer
{
    public Dictionary<string, string> GetMediaTypeParameters()
    {
        return new Dictionary<string, string> { { DataUri.CONTENT_ENCODING, GZip.GZIP } };
    }

    public byte[] Serialize(object obj)
    {
        string stringObj = JsonConvert.SerializeObject(obj);
        return GZip.Encode(stringObj);
    }
}
var serializationSettings = new ObjectSerializationSettings(new GZipSerializer(), "application/json", true, null);
Person andrew = new Person()
{
    Name = "andrew"
};
DataUri dataUriGZip = DataUri.FromObject(andrew, serializationSettings);