Use JSON.NET to generate JSON schema with extra attributes

Question

I am using JSON.NET to generate JSON Schema from c# object class. But I was unable to add any other json schema attributes e.g. maxLength, pattern(regex to validate email),

Answer 1

You can create custom JsonConverter something like this. I used reflection to fill out properties.

  public class UserConverter : JsonConverter
{
    public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
    {
        var user = (User)value;
        var result = new StringBuilder("{");

        result.Append("title : " + user.GetType().Name + ", ");
        result.Append("properties : {");

        foreach (var prop in user.GetType().GetProperties())
        {
            result.Append(prop.Name + ": {");
            result.Append("value : " + Convert.ToString(prop.GetValue(user, null)) + ", ");

            var attribute = (JsonPropertyAttribute)Attribute.GetCustomAttributes(prop)[0];
            if (attribute.Required == Required.Always)
                result.Append("required : true, ");

            result.Append("type : " + prop.PropertyType.Name.ToLower());
            result.Append(" }");
        }
        writer.WriteValue(result.ToString());
    }

    public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
    {
        var user = new User { UserName = (string)reader.Value };

        return user;
    }

    public override bool CanConvert(Type objectType)
    {
        return objectType == typeof(User);
    }

}

---

[JsonConverter(typeof(UserConverter))]
public class User
{
    [JsonProperty(Required = Required.Always)]
    public string UserName { get; set; }
}

//Run  
string json = JsonConvert.SerializeObject(manager, Formatting.Indented);

Console.WriteLine(json);