C# saving any JSON string as a Firestore document

Question

I'm trying to retrieve a document from Firestore, edit it as a plain-text JSON, and then reupload the changes. I'm using JSON.net to deserialize the string to Dictionary<string, object>, and then pass it on to SetAsync();:

public static async void SaveDocumentDataAsync(string documentAccessPath, string documentData)
{
     DocumentReference documentRef = firestoreDb.Document(documentAccessPath);
     Dictionary<string, object> document = JsonConvert.DeserializeObject<Dictionary<string, object>>(documentData);
     await documentRef.SetAsync(document);
}

This works perfectly if the JSON object is simple, like:

{
    "foo": "bar"
}

But if it has nested elements, everything above the root properties gets saved as an empty array (the keys are all correct, though):

{
    "foo": "bar"
    "baz": {
         "property1": 6,          // will be saved to Firestore as "property1": [],
         "property2": ["text", 5] // will be saved to Firestore as "property2": [],
    }

}

The closest I got to some sort of solution is using Dictionary<string, Dictionary<string, object>> but this only works for root and second level properties, everything else is saved as an empty array again.

Is there a simple way, or any way, to just translate JObject to Dictionaries with only the key and the actual values in them?

I've been trying to find something for a good while but none of the other solutions worked, and I can't make custom classes for the documents, because their contents can be anything, no specific structure.

Answer 1

It turns out that JsonConvert.DeserializeObject only parses the first level of data. We need to handle the Dictionary conversion recursively for Firestore to understand our nested document structure properly.

using Newtonsoft.Json.Linq;

public static async Task SaveDocumentDataAsync(string documentAccessPath, string documentData)
{
    DocumentReference documentRef = firestoreDb.Document(documentAccessPath);
    Dictionary<string, object> document = JObjectToDictionary(JObject.Parse(documentData));
    await documentRef.SetAsync(document);
}

private static object JTokenToObject(JToken token)
{
    switch (token.Type)
    {
        case JTokenType.Object:
            return JObjectToDictionary((JObject)token);
        case JTokenType.Array:
            var array = new List<object>();
            foreach (var item in (JArray)token)
            {
                array.Add(JTokenToObject(item));
            }
            return array;
        default:
            return ((JValue)token).Value;
    }
}

private static Dictionary<string, object> JObjectToDictionary(JObject obj)
{
    var result = new Dictionary<string, object>();

    foreach (var property in obj.Properties())
    {
        result[property.Name] = JTokenToObject(property.Value);
    }

    return result;
}