Why is JsonSerializer.Deserializer only partially populating my object?

Question

I have a class defined as follows:

public class NearestLocation
{
    public Int32 ID { get; set; }
    public String Name { get; set; }
    public String TypeID { get; set; }
    public String SourceID { get; set; }
    public String Code { get; set; }
    public Double Latitude;
    public Double Longitude;
    public Int32? Distance { get; set; }
    public String Direction { get; set; }
    public String Relative { get; set; }
    public DateTime? LastUpdatedOn { get; set; }
}

and a string jsonData returned from an API call that contains the following JSON:

{\"Latitude\":-45.861900329589844,\"Longitude\":170.36294555664063,\"Distance\":13,\"Direction\":\"E\",\"Relative\":\"Helicopters Otago (South)\",\"ID\":413,\"Code\":\"HOLS\",\"Name\":\"Helicopters Otago (South)\",\"TypeID\":\"helipad\",\"SourceID\":\"holcwh\",\"LastUpdatedOn\":\"2022-05-08T23:18:41.987\"}

When I deserialize jsonData into an object as follows:

NearestLocation nearest = JsonSerializer.Deserialize<NearestLocation>(jsonData);

nearest is only partially populated:

Code: "HOLS"    
Direction: "E"  
Distance: 13    
ID: 413
LastUpdatedOn: {8/05/2022 11:18:41 pm}  
Latitude: 0 
Longitude: 0    
Name: "Helicopters Otago (South)"
Relative: "Helicopters Otago (South)"
SourceID: "holcwh"
TypeID: "helipad"

Why are Latitude and Longitude not being populated? I can see the correct values in the JSON, and other values - of types String, Int32 and DateTime - are all being populated correctly. It is only the doubles that are not being populated correctly.

I don't seem to be able to trace into JsonSerializer to see what's going on under the hood - the debugger just steps over the line. I've checked the names in the JSON and in the class definition to make sure they match - which they do - but I am at a loss to understand why this is happening.

Answer 1

Latitude and Longitude are fields. Adding getter and setter in order to convert them to properties.

public class NearestLocation
{
    // Other properties
    public double Latitude { get; set; } 
    public double Longitude { get; set; }
}

From the documentation,

By default, fields are ignored. You can include fields.

To include field for serialization/deserialization, you need to apply the [JsonInclude] attribute as mentioned.