DataContractJsonSerializer doesn't work with formatted JSON?

Question

When using the DataContractJsonSerializer to deserialize JSON, if the input has tabs in it (formatted JSON) then the serializer throws an exception (shown below). If I replace all of the spaces, tabs and new-lines with "", the serializer is able to deserialize it just fine.

What's the deal?

Exception

System.MemberAccessException: Cannot create an abstract class.
at System.Runtime.Serialization.FormatterServices.nativeGetUninitializedObject(RuntimeType type) 
at System.Runtime.Serialization.FormatterServices.GetUninitializedObject(Type type) 
at System.Runtime.Serialization.XmlFormatReaderGenerator.UnsafeGetUninitializedObject(Int32 id) 
at ReadBaseSearchElementFromJson(XmlReaderDelegator , XmlObjectSerializerReadContextComplexJson , XmlDictionaryString , XmlDictionaryString[] ) 
at System.Runtime.Serialization.Json.JsonClassDataContract.ReadJsonValueCore(XmlReaderDelegator jsonReader, XmlObjectSerializerReadContextComplexJson context) 
at System.Runtime.Serialization.Json.JsonDataContract.ReadJsonValue(XmlReaderDelegator jsonReader, XmlObjectSerializerReadContextComplexJson context) 
at System.Runtime.Serialization.Json.XmlObjectSerializerReadContextComplexJson.ReadDataContractValue(DataContract dataContract, XmlReaderDelegator reader) 
at System.Runtime.Serialization.XmlObjectSerializerReadContext.InternalDeserialize(XmlReaderDelegator reader, String name, String ns, Type declaredType, DataContract& dataContract) 
at System.Runtime.Serialization.XmlObjectSerializerReadContextComplex.InternalDeserialize(XmlReaderDelegator xmlReader, Int32 declaredTypeID, RuntimeTypeHandle declaredTypeHandle, String name, String ns) 
at ReadSearchElementsFromJson(XmlReaderDelegator , XmlObjectSerializerReadContextComplexJson , XmlDictionaryString , XmlDictionaryString , CollectionDataContract ) 
at System.Runtime.Serialization.Json.JsonCollectionDataContract.ReadJsonValueCore(XmlReaderDelegator jsonReader, XmlObjectSerializerReadContextComplexJson context) 
at System.Runtime.Serialization.Json.JsonDataContract.ReadJsonValue(XmlReaderDelegator jsonReader, XmlObjectSerializerReadContextComplexJson context) 
at System.Runtime.Serialization.Json.XmlObjectSerializerReadContextComplexJson.ReadDataContractValue(DataContract dataContract, XmlReaderDelegator reader) 
at System.Runtime.Serialization.XmlObjectSerializerReadContext.InternalDeserialize(XmlReaderDelegator reader, String name, String ns, Type declaredType, DataContract& dataContract) 
at System.Runtime.Serialization.XmlObjectSerializerReadContextComplex.InternalDeserialize(XmlReaderDelegator xmlReader, Int32 declaredTypeID, RuntimeTypeHandle declaredTypeHandle, String name, String ns) 
at ReadSearchGroupFromJson(XmlReaderDelegator , XmlObjectSerializerReadContextComplexJson , XmlDictionaryString , XmlDictionaryString[] ) 
at System.Runtime.Serialization.Json.JsonClassDataContract.ReadJsonValueCore(XmlReaderDelegator jsonReader, XmlObjectSerializerReadContextComplexJson context) 
at System.Runtime.Serialization.Json.JsonDataContract.ReadJsonValue(XmlReaderDelegator jsonReader, XmlObjectSerializerReadContextComplexJson context) 
at System.Runtime.Serialization.Json.XmlObjectSerializerReadContextComplexJson.ReadDataContractValue(DataContract dataContract, XmlReaderDelegator reader) 
at System.Runtime.Serialization.XmlObjectSerializerReadContext.InternalDeserialize(XmlReaderDelegator reader, String name, String ns, Type declaredType, DataContract& dataContract) 
at System.Runtime.Serialization.XmlObjectSerializerReadContextComplex.InternalDeserialize(XmlReaderDelegator xmlReader, Type declaredType, DataContract dataContract, String name, String ns) 
at System.Runtime.Serialization.Json.DataContractJsonSerializer.InternalReadObject(XmlReaderDelegator xmlReader, Boolean verifyObjectName) 
at System.Runtime.Serialization.XmlObjectSerializer.InternalReadObject(XmlReaderDelegator reader, Boolean verifyObjectName, DataContractResolver dataContractResolver) 
at System.Runtime.Serialization.XmlObjectSerializer.ReadObjectHandleExceptions(XmlReaderDelegator reader, Boolean verifyObjectName, DataContractResolver dataContractResolver) 
at System.Runtime.Serialization.Json.DataContractJsonSerializer.ReadObject(XmlDictionaryReader reader) 
at System.Runtime.Serialization.Json.DataContractJsonSerializer.ReadObject(Stream stream)

Formatted JSON

This does not deserialize, throwing the exception above.

{
    "Mode":"And",
    "Elements":
    [
        {
            "Name":"ID",
            "Operator":"Equal",
            "Value":"3"
        }
    ]
}

Non-formatted JSON

This does deserialize.

{"Mode":"And","Elements":[{"Name":"ID","Operator":"Equal","Value":"3"}]}

Update

I've posed a sample solution which exhibits this problem.

Answer 1

Most of your formatting is actually fine. You just can't have any whitespace between { and "__type".

See this previous answer: JSON deseralization to abstract list using DataContractJsonSerializer

So for instance, your sample code is trying to deserialize this JSON string:

"{\r\n\t\"Mode\":\"And\",\r\n\t\"Elements\":\r\n\t[\r\n\t\t{\r\n\t\t\t\"__type\":\"SearchParameter:#JsonTest.Search\",\r\n\t\t\t\"Name\":\"LastName\",\r\n\t\t\t\"Operator\":\"Equal\",\r\n\t\t\t\"Value\":\"Smith\"\r\n\t\t},\r\n\t\t{\r\n\t\t\t\"__type\":\"SearchGroup:#JsonTest.Search\",\r\n\t\t\t\"Mode\":\"Or\",\r\n\t\t\t\"Elements\":\r\n\t\t\t[\r\n\t\t\t\t{\r\n\t\t\t\t\t\"__type\":\"SearchParameter:#JsonTest.Search\",\r\n\t\t\t\t\t\"Name\":\"FirstName\",\r\n\t\t\t\t\t\"Operator\":\"Equal\",\r\n\t\t\t\t\t\"Value\":\"Tim\"\r\n\t\t\t\t},\r\n\t\t\t\t{\r\n\t\t\t\t\t\"__type\":\"SearchParameter:#JsonTest.Search\",\r\n\t\t\t\t\t\"Name\":\"FirstName\",\r\n\t\t\t\t\t\"Operator\":\"Equal\",\r\n\t\t\t\t\t\"Value\":\"Tom\"\r\n\t\t\t\t}\r\n\t\t\t]\r\n\t\t}\r\n\t]\r\n}"

Formatted:

{
    "Mode":"And",
    "Elements":
    [
        {
            "__type":"SearchParameter:#JsonTest.Search",
            "Name":"LastName",
            "Operator":"Equal",
            "Value":"Smith"
        },
        {
            "__type":"SearchGroup:#JsonTest.Search",
            "Mode":"Or",
            "Elements":
            [
                {
                    "__type":"SearchParameter:#JsonTest.Search",
                    "Name":"FirstName",
                    "Operator":"Equal",
                    "Value":"Tim"
                },
                {
                    "__type":"SearchParameter:#JsonTest.Search",
                    "Name":"FirstName",
                    "Operator":"Equal",
                    "Value":"Tom"
                }
            ]
        }
    ]
}

Change it to this, and the error goes away:

"{\r\n\t\"Mode\":\"And\",\r\n\t\"Elements\":\r\n\t[\r\n\t\t{\"__type\":\"SearchParameter:#JsonTest.Search\",\r\n\t\t\t\"Name\":\"LastName\",\r\n\t\t\t\"Operator\":\"Equal\",\r\n\t\t\t\"Value\":\"Smith\"\r\n\t\t},\r\n\t\t{\"__type\":\"SearchGroup:#JsonTest.Search\",\r\n\t\t\t\"Mode\":\"Or\",\r\n\t\t\t\"Elements\":\r\n\t\t\t[\r\n\t\t\t\t{\"__type\":\"SearchParameter:#JsonTest.Search\",\r\n\t\t\t\t\t\"Name\":\"FirstName\",\r\n\t\t\t\t\t\"Operator\":\"Equal\",\r\n\t\t\t\t\t\"Value\":\"Tim\"\r\n\t\t\t\t},\r\n\t\t\t\t{\"__type\":\"SearchParameter:#JsonTest.Search\",\r\n\t\t\t\t\t\"Name\":\"FirstName\",\r\n\t\t\t\t\t\"Operator\":\"Equal\",\r\n\t\t\t\t\t\"Value\":\"Tom\"\r\n\t\t\t\t}\r\n\t\t\t]\r\n\t\t}\r\n\t]\r\n}"

Formatted:

{
    "Mode":"And",
    "Elements":
    [
        {"__type":"SearchParameter:#JsonTest.Search",
            "Name":"LastName",
            "Operator":"Equal",
            "Value":"Smith"
        },
        {"__type":"SearchGroup:#JsonTest.Search",
            "Mode":"Or",
            "Elements":
            [
                {"__type":"SearchParameter:#JsonTest.Search",
                    "Name":"FirstName",
                    "Operator":"Equal",
                    "Value":"Tim"
                },
                {"__type":"SearchParameter:#JsonTest.Search",
                    "Name":"FirstName",
                    "Operator":"Equal",
                    "Value":"Tom"
                }
            ]
        }
    ]
}

Answer 2

Weird. You may want to try JSON.NET, a nice library for JSON serialization and deserialization. I've used it in a project recently and it worked in cases where the DataContractJsonSerializer had failed.

You can find it at http://json.codeplex.com/