Tukukkk

I'm having trouble serialising an object graph using NewtonSoft JsonConvert. Dapper can work in two ways: the Query(string sql[, object args]) method can return an IEnumerable<dynamic> or the generic Query<T>(string sql[, object args]) method can return IEnumerable<T>

It works when I don't type the result:

stringifiedDynamicData

[{"Record_Key":2,"Factory_Key":7,"EnteredAt":"2018-11-20T09:03:03.374",...}]

When I specify a type for the result, results look like this:

stringifiedTypedData

[{}]

Here's the code that produced the above.

IDbConnection syb = new OdbcConnection(connectionstring);

var sql = System.IO.File.ReadAllText("./powerbi.sybase");

var typedData = syb.Query<Status>(sql);

var stringifiedTypedData = JsonConvert.SerializeObject(typedData); 

Console.WriteLine("stringifiedTypedData");

Console.WriteLine(stringifiedTypedData);

var dynamicData = syb.Query(sql);

var stringifiedDynamicData = JsonConvert.SerializeObject(dynamicData);

Console.WriteLine("stringifiedDynamicData");

Console.WriteLine(stringifiedDynamicData);      

Debug inspection of the variable typedData reveals a collection of Status objects with one element, as expected. The fields have expected values, so it was a bit of a surprise when JsonConvert.Deserialize(typedData) returned [{}]

Adding this

  var foo = new {

    A = "wibble", B = 6

  };

  IEnumerable<object> bar = from x in new object { foo } select x;

  var quux = JsonConvert.SerializeObject(bar);

  Console.WriteLine("quux");

  Console.WriteLine(quux);

produces the expected result

quux

[{"A":"wibble","B":6}]

which implies that the data is the problem.
so it isn't some sort of config problem.

The Status class has this form.

public class Status

{

  float AdtechAmt { get; set; } = -1;

  float AssemblyError { get; set; } = -1;

  string CutToFinish_Avg { get; set; } = "-1";

  ...

}

I've just added the default values to see whether that makes a difference (no).

I think I've been using Typescript for too long, it just hit me that these properties are not public.

Fundamentally this is Bonehead Programmer Error, with a twist of Typescript.

Both C# and Typescript support properties without a modifier. But while unmodified Typescript properties default to public, in C# they default to protected. As there is no requirement for a class to have any public properties, no static compiler error occurs.

Dapper uses reflection and can see the protected members, and successfully matches them to dataset fields, and populates them. Dapper's successful use of the class for typing results further masks the failure to make the properties public.

The first visible effect is the property-free serialisation. The reason there's no exception is that all the objects (one row in this case) have been successfully serialised, with all the public properties (none) represented in the JSON string.