Menu
I'm receiving a JSON object from a public API with a property that, itself, is an escaped JSON string.
{
"responses":[
{
"info":"keep \"this\" in a string",
"body":"{\"error\":{\"message\":\"Invalid command\",\"type\":\"Exception\",\"code\":123}}"
},
{
"info":"more \"data\" to keep in a string",
"body":"{\"error\":{\"message\":\"Other error\",\"type\":\"Exception\",\"code\":321}}"
}
]
}
How do I convert this property into an actual JSON object (unescaped) in order to deserialize the entire response using NewtonSoft Json.NET?
212
Your JSON contains a literal string for the "body" objects that is actually embedded, double-serialized JSON. To deserialize this to a POCO hierarchy without needing to introduce an intermediate string Json surrogate property inside any of your types, you have a few options:
You could preprocess your JSON using LINQ to JSON and replace the literal "body" strings with their parsed equivalents:
var rootToken = JToken.Parse(json);
foreach (var token in rootToken.SelectTokens("responses[*].body").ToList().Where(t => t.Type == JTokenType.String))
{
token.Replace(JToken.Parse((string)token));
}
var root = rootToken.ToObject<RootObject>();
You could introduce a generic JsonConverter for the POCO corresponding to each Body object that parses the incoming embedded JSON string literal into a LINQ to JSON hierarchy, then deserializes that:
public class EmbeddedLiteralConverter<T> : JsonConverter
{
public override bool CanConvert(Type objectType)
{
return typeof(T).IsAssignableFrom(objectType);
}
public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
{
if (reader.TokenType == JsonToken.Null)
return null;
var contract = serializer.ContractResolver.ResolveContract(objectType);
if (contract is JsonPrimitiveContract)
throw new JsonSerializationException("Invalid type: " + objectType);
if (existingValue == null)
existingValue = contract.DefaultCreator();
if (reader.TokenType == JsonToken.String)
{
var json = (string)JToken.Load(reader);
using (var subReader = new JsonTextReader(new StringReader(json)))
{
// By populating a pre-allocated instance we avoid an infinite recursion in EmbeddedLiteralConverter<T>.ReadJson()
// Re-use the existing serializer to preserve settings.
serializer.Populate(subReader, existingValue);
}
}
else
{
serializer.Populate(reader, existingValue);
}
return existingValue;
}
public override bool CanWrite { get { return false; } }
public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
{
throw new NotImplementedException();
}
}
Then use it like:
var root = JsonConvert.DeserializeObject<RootObject>(json, new EmbeddedLiteralConverter<Body>());
Note that the converter checks to see whether the incoming JSON token is a string, and if not, deserializes directly. Thus the converter should be usable when the "body" JSON is and is not double-serialized.
For testing purposes I generated the following target classes using http://json2csharp.com/:
public class Error
{
public string message { get; set; }
public string type { get; set; }
public int code { get; set; }
}
public class Body
{
public Error error { get; set; }
}
public class Respons
{
public string info { get; set; }
public Body body { get; set; }
}
public class RootObject
{
public List<Respons> responses { get; set; }
}
To convert a json encoded as json string to Jobject, you can always use the technique below,
var token = JToken.Parse(text);
var json = JObject.Parse((string) token);
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With
