Bad Request -Post method - JSON DateTime issue - json

Question

I have a Visual Studio (2015) project that includes a client part (Xamarin.Forms PCL) and a web service part ( WCF Rest). The web services use edmx to communicate with the database ( SQL Server 2016). JSON is used to exchange the data.
I'm new to creating/consuming WCF Rest services. I have no issue using the GET method but I'm stuck with an issue with a POST method.
This method is part of a service that works well: no issue for a GET based method. It works well when I test it from a URL or from my client ( PCL Xamarin.Forms).
The POST method (my first ever) is a bit more problematic.
It's supposed to create a new record in a table in SQL Server (2016).
When I use Postman (https://www.getpostman.com/) to test it, it already has an issue: it creates a record in the table but the object has two dates and the two dates are replaced by 1970-01-01.
When I use my client to contact the web service:I get 'Bad Request'.
I looked for a solution and found that instead of placing the Datetime value, it was best to place the number of milliseconds from 1970-01-01.
I used this advice in Postman and noticed the creation of a new line worked fine.
Body of the Postman request :
{
"Reservation_Utilisateur_Id" : "4",
"Reservation_Velo_Id" : "2",
"Reservation_DateDebut" : "\/Date(1245398693390)\/",
"Reservation_PeriodeDebut" : "matin",
"Reservation_DateFin" :"\/Date(1245398693390)\/",
"Reservation_PeriodeFin" : "matin"
}
Now, I'd like to know how to get that object to send to the server . How can my object be serialized like above?
I looked for a solution unsuccessfully.
I keep on getting "There was an error deserializing the object of type BikeSharingService.Reservation. DateTime content '2016-08-22T00:00:00+02:00' does not start with '/Date(' and end with ')/' as required for JSON."
Could someone please give the newbie that I am an explanation and maybe some code that works?
Here is my code:
My contract:
[OperationContract]
[WebInvoke(Method = "POST", UriTemplate = "create",
ResponseFormat = WebMessageFormat.Json, RequestFormat = WebMessageFormat.Json)]
Reservation create(Reservation reservation);
The service method:
public Reservation create(Reservation reservation)
{
using (MyEntities bse = new MyEntities())
{
Reservation re = new Reservation
{
Reservation_Utilisateur_Id = reservation.Reservation_Utilisateur_Id,
Reservation_Velo_Id = reservation.Reservation_Velo_Id,
Reservation_DateDebut = reservation.Reservation_DateDebut,
Reservation_PeriodeDebut = reservation.Reservation_PeriodeDebut,
Reservation_DateFin = reservation.Reservation_DateFin,
Reservation_PeriodeFin = reservation.Reservation_PeriodeFin,
Reservation_DemandeRecupDomCli = reservation.Reservation_DemandeRecupDomCli
};
bse.Reservations.Add(re);
bse.SaveChanges();
return re;
}
}
On the client side :
const string Url1 = "http://localhost:51843/ServiceReservation.svc/create";
public async Task<Reservation> create(Reservation reservation)
{
string json = JsonConvert.SerializeObject(reservation);
var client = new HttpClient();
client.DefaultRequestHeaders.Add("Accept", "application/json");
var response = await client.PostAsync(Url1,
new StringContent(
json,
Encoding.UTF8, "application/json"));
return JsonConvert.DeserializeObject<Reservation>(
await response.Content.ReadAsStringAsync());
}
Then calling the method on the client side :
Reservation re =new Reservation();
re.Reservation_Utilisateur_Id = 4;
re.Reservation_Velo_Id = 2;
re.Reservation_DateDebut = DateTime.Now.Date;
re.Reservation_PeriodeDebut = "matin";
re.Reservation_DateFin = DateTime.Now.Date;
re.Reservation_PeriodeFin = "matin";
re.Reservation_DemandeRecupDomCli = 1;
Reservation resultat = await reManager.create(re);
What I get :
False Bad Request Method: POST, RequestUri:
'http://localhost:51843/ServiceReservation.svc /create', Version: 2.0,
Content: System.Net.Http.StringContent, Headers: { Accept:
application/json Content-Type: application/json; charset=utf-8
Content-Length: 407 } BadRequest
1.1
There was an error deserializing the object of type
BikeSharingService.Reservation. DateTime content
'2016-08-22T00:00:00+02:00' does not start with '/Date(' and end with
')/' as required for JSON.

Answer 1

[Promoted from a comment]
Json doesn't define a standard date format, but it's worth noting that Json.Net (which is used by most of the web-facing parts of the .Net framework) supports multiple formats out of the box (and even custom ones).
If you can decide on a standard which works for all your clients, you can configure the Json (en/de)coding in .Net to use it natively.
See http://newtonsoft.com/json/help/html/datesinjson.htm for more information and details on how to specify a date format handler.
[Example code from link]
public void WriteJsonDates()
{
LogEntry entry = new LogEntry
{
LogDate = new DateTime(2009, 2, 15, 0, 0, 0, DateTimeKind.Utc),
Details = "Application started."
};
// default as of Json.NET 4.5
string isoJson = JsonConvert.SerializeObject(entry);
// {"Details":"Application started.","LogDate":"2009-02-15T00:00:00Z"}
JsonSerializerSettings microsoftDateFormatSettings = new JsonSerializerSettings
{
DateFormatHandling = DateFormatHandling.MicrosoftDateFormat
};
string microsoftJson = JsonConvert.SerializeObject(entry, microsoftDateFormatSettings);
// {"Details":"Application started.","LogDate":"\/Date(1234656000000)\/"}
string javascriptJson = JsonConvert.SerializeObject(entry, new JavaScriptDateTimeConverter());
// {"Details":"Application started.","LogDate":new Date(1234656000000)}
}

Answer 2

What you are trying to use is the Epoch DateTime or Unix DateTime.
To convert the DateTime object to epoch datetime you can create a helper method. It is either milliseconds or seconds from 1/1/1970.
Also if needed you can use the Noda DateTime instead of the .NET which has the method in it to convert.
You can create a New class with string data type for DateTime and have a Casting specified. Or you can write your on custom Serialize method.
By default DateTime format after serialization would be ISO 8601 Format.
Code to convert to Unix or Epoch Date time :
private static readonly DateTime EpochDateTime = new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc);
public static long ConvertDateTimeToUnixTime(DateTime date, bool isDatarequiredInMilliSeconds = false, DateTimeKind dateTimeKind = DateTimeKind.Local)
{
return Convert.ToInt64((DateTime.SpecifyKind(date.Value, dateTimeKind).ToUniversalTime() - EpochDateTime).TotalSeconds) * (isDatarequiredInMilliSeconds ? 1000 : 1);
}
You can use the following if you need to convert back(source):
var milliseconds = "/Date(1245398693390)/".replace(/\/Date\((-?\d+)\)\//, '$1');
var actualDate = new Date(parseInt(milliseconds));