Adding fields to arbitrary JSON


Is it possible to add fields to an arbitrary JSON string/object? I need to modifiy a Solr configuration using their REST API and their format is a bit…special/unstructured so I cannot create a POCO.

For example, if I have this JSON object:

    "Name": "Freddie",
    "Age": 12,
    "Favorite": ["a", "b"],
    "Street": "47"

Is there a way to add a new field to this JSON without changing the structure? I tried using JsonObject to read the object and JsonSerializer however this method changes the Street property from a string to a number which causes issues with the program that ultimately interpret the data (a Solr server):

    "Favorite":["a", "b"],

I tried deserializing the JSON to a Dictionary<string, object> which causes the Favorite array to be mangled (it becomes "[a, b]"). I also tried the DynamicJson object however I had 2 issues with it:

  • It looks like the string is read as a Dictionary<string, string> which causes issues with the Street property as with JsonObject
  • I was not able to serialize a dynamic object made from DynamicJson:
var str = @"{
                ""Name"": ""Freddie"",
                ""Age"": 12,
                ""Favorite"": [""a"", ""b""],
                ""Street"": ""47""
var dynJs = DynamicJson.Deserialize(str);
var serializedValue = DynamicJson.Serialize(dynJs); // this value is always {}
  • I should point out that serializing an anonymous object (new { A = 3 }) works as expected.

Is it possible to achieve what I want to do (adding a field without modifying the structure) or am I screwed? I realize this is a weird requirement. I added the real Solr JSON below.



No the JsonObject is the closest thing to be able to read an unstructured JSON document, but it’s backed by a string Dictionary which means it looks at the value to determine how to serialize its contents which is why Street “47” is serialized as a number and not a string.

Normally I’d say read it into a POCO, modify it and serialize it again but it looks like they’re using an unconventional format that doesn’t map well to POCO’s. There’s no good solution in ServiceStack for this so you’d need to go shopping elsewhere.

I figured this JSON was too unconventional to do what I need. Hopefully I can find a (slower) serializer that can handle what I need.