Why does DataContractJsonSerializer skip deserializing some properties?

Question

We ran into a weird problem recently where two properties from a JSON object weren't being deserialized.

Given this class:

[DataContract]
public class Hotel
{
  [DataMember]
  public string Name { get; set; }

  .... other properties

  [DataMember]
  public string double? Latitude { get; set; }

  [DataMember]
  public string double? Longitude { get; set; }

  .... other properties
}    

and a matching JSON string:

{
  "Address":"123 Maple Avenue",
  "Name":"My Awesome Hotel",
  "Phone":"+15550001212",
  "PostalCode":"",
  "Province":"ON",
  "latitude":45.421530,
  "longitude":-75.697193
}

Neither the latitude nor longitude properties were being set.

Here's the deserialization code:

public static object Deserialize(Type concreteType, string serialized)
{
   var jsonBytes = Encoding.UTF8.GetBytes(serialized);
   using (var jsonReader = JsonReaderWriterFactory.CreateJsonReader
                           (jsonBytes, XmlDictionaryReaderQuotas.Max))
   {
      var dcjs = new DataContractJsonSerializer(concreteType);
      return dcjs.ReadObject(jsonReader);
   }
}

What was extremely puzzling is that other classes with the same latitutde / longitude properties were being deserialized correctly. To be clear: there were other classes deserializing JSON strings where the names in the JSON were lower-case and the C# properties were in PascalCase.

(Interestingly enough, JSON.Net was able to deserialize this without any problem)

So what was happening with DataContractJsonSerializer and this particular string?

Answer 1

As it turns out, DataContractJsonSerializer expects all the properties in the JSON string to be in alphabetical order if they're not capitalized. Changing the data to

{
  "Address":"123 Maple Avenue",
  "latitude":45.421530,
  "longitude":-75.697193
  "Name":"My Awesome Hotel",
  "Phone":"+15550001212",
  "PostalCode":"",
  "Province":"ON",
}

made the object deserialize perfectly.

(Leaving the properties in the same order and capitalizing the 'L' also worked, as expected)

Answer 2

纬度和经度在JSON中为小写字母，但对象的属性具有大写L