Deserialize json with known and unknown fields

Question

Given following json result: The default json result has a known set of fields: ``` { "id": "7908", "name": "product name" } ``` But can be extended with additional fields (in this example `_unknown_field_name_1` and `_unknown_field_name_2`) of which the names are not known when requesting the result. ``` { "id": "7908", "name": "product name", "_unknown_field_name_1": "some value", "_unknown_field_name_2": "some value" } ``` I would like the json result to be serialized and deserialized to and from a class with properties for the known fields and map the unknown fields (for which there are no properties) to a property (or multiple properties) like a dictionary so they can be accessed and modified. ``` public class Product { public string id { get; set; } public string name { get; set; } public Dictionary<string, string> fields { get; set; } } ``` I think I need a way to plug into a json serializer and do the mapping for the missing members myself (both for serialize and deserialize).…

Accepted Answer

An even easier option to tackling this problem would be to use the JsonExtensionDataAttribute from JSON .NET

```
public class MyClass
{
   // known field
   public decimal TaxRate { get; set; }

// extra fields
   [JsonExtensionData]
   private IDictionary<string, JToken> _extraStuff;
}
```

There's a sample of this on the project blog here

UPDATE Please note this requires JSON .NET v5 release 5 and above

Deserialize json with known and unknown fields

Solution

Problem