Deserialize JSON from request body with dynamic keys

Question

I have a Rest API that accepts a JSON model consisting of its fields are dynamic GUIDs.

I tried multiple models and in all of them, I got an error.

This is the JSON:

{
   "meta_data": {
       "name": "myname"
   },
   "1122413f-2887-4789-a112-31d003f2703a": {
       "ipadd": "1.1.1.1",
       "host": "host"
   },
   "4432313f-2887-4789-a222-31d41231233a": {
       "ipadd": "1.2.1.1",
       "host": "h3st"
   }
}

and this is the model:

public class RootObject
{
    [JsonProperty("meta_data")]
    public Metadata Metadata { get; set; }

    public Dictionary<Guid, DeviceInfo> Devices { get; set; }
}

public class DeviceInfo
{
    public string IpAdd { get; set; }
    public string Host { get; set; }
}

and the controller:

[FromBody] RootObject jsonObj

The jsonObj only contains the Metadata and the dynamic field is always empty.

What can I do to overcome this?

It accepts when I send it under Devices:

"Devices": { 
     "123...."
}

but this is not what I need.

Answer 1

If you are using .NET Core 3 and above, you can work with JsonExtensionDataAttribute from System.Text.Json.Serialization.

You should add a new property for receiving the additional JSON element as Dictionary<string, JsonElement>.

The dictionary's TKey value must be String, and TValue must be JsonElement or Object.

And assign it to the Devices property with some data conversions.

using System.Text.Json.Serialization;
using System.Linq;

public class RootObject
{
    [JsonPropertyName("meta_data")]
    public Metadata Metadata { get; set; }

    [JsonExtensionData]
    public Dictionary<string, JsonElement> Extension { get; set; }
    
    [JsonIgnore]
    public Dictionary<Guid, DeviceInfo> Devices 
    { 
        get
        {
            if (Extension == null)
                return null;

            return Extension.ToDictionary(x => Guid.Parse(x.Key), v => JsonSerializer.Deserialize<DeviceInfo>(JsonSerializer.Serialize(v.Value)));
        }
    }
}

public class DeviceInfo
{
    [JsonPropertyName("ipadd")]
    public string IpAdd { get; set; }
    
    [JsonPropertyName("host")]
    public string Host { get; set; }
}

---

If you are using Newtonsoft.Json as the default serialization library/tool in your API/MVC application:

services.AddControllers()
    .AddNewtonsoftJson();

You need to use the attributes/deserialization ways from Newtonsoft.Json.

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

public class RootObject
{
    [JsonProperty("meta_data")]
    public Metadata Metadata { get; set; }

    [JsonExtensionData]
    public Dictionary<string, JToken> Extension { get; set; }

    [JsonIgnore]
    public Dictionary<Guid, DeviceInfo> Devices
    {
        get
        {
            if (Extension == null)
                return null;

            return Extension.ToDictionary(x => Guid.Parse(x.Key), 
                v => JObject.FromObject(v.Value)
                    .ToObject<DeviceInfo>());
        }
    }
}

public class DeviceInfo
{
    [JsonProperty("ipadd")]
    public string IpAdd { get; set; }

    public string Host { get; set; }
}