Serialize object to JSON that already contains one JSON property

Question

In order to increase performance, I have cached the result of a larger operation as JSON in a table - together with a key column to determine which row(s) to return. So the

Answer 1

You could make a JsonConverter to write the raw value of the string property to the output without changing it. You take responsibility for ensuring the string has valid JSON or else the resulting output will not be valid JSON either.

Here is what the converter might look like:

class RawJsonConverter : JsonConverter
{
    public override bool CanConvert(Type objectType)
    {
        return (objectType == typeof(string));
    }

    public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
    {
        // write value directly to output; assumes string is already JSON
        writer.WriteRawValue((string)value);  
    }

    public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
    {
        // convert parsed JSON back to string
        return JToken.Load(reader).ToString(Formatting.None);  
    }
}

To use it, mark your JSON property with a [JsonConverter] attribute like this:

class Foo
{
    ...
    [JsonConverter(typeof(RawJsonConverter))]
    public string YourJsonProperty { get; set; }
    ...
}

Here is a demo: https://dotnetfiddle.net/BsTLO8