ASP.NET Controller FormatException: String was not recognized as a valid DateTime

Question

In Postman, I'm sending the following JSON via a POST to API.

{
"id": "21",
"crgName": "Walgreens - 11/07/2018 - Standard ",
"crgStarteddatetime": "2018-11-07T10:11:10",
}

...but, I get the following error: FormatException: String was not recognized as a valid DateTime.

Inside my controller, I'm using DateTimeFormat to format the date time:

 public static RemoteContextType DeserializeJsonString<RemoteContextType>(string jsonString)
 {
 //create an instance of generic type object
 RemoteContextType obj = Activator.CreateInstance<RemoteContextType>();
 MemoryStream ms = new MemoryStream(Encoding.Unicode.GetBytes(jsonString));
 var serializer = new DataContractJsonSerializer(obj.GetType(),
 new DataContractJsonSerializerSettings
 {
 DateTimeFormat = new
 DateTimeFormat("yyyy-MM-dd'T'HH:mm:ss.fff'Z'")
 });
 obj = (RemoteContextType)serializer.ReadObject(ms);
 ms.Close();
 return obj;
 }

...is there an issue in my syntax as to how I have the Date formatted? My intentions are to formate the date as it is reflected in the JSON. Could I get some help as to what am I doing wrong?

Answer 1

The problem lies in this line:

DateTimeFormat = new DateTimeFormat("yyyy-MM-dd'T'HH:mm:ss.fff'Z'")

You're specifying the format exactly as UTC/Zulu datetime with 'Z' format specifier and 3 digits of seconds fraction (fff format specifier), but the value used in crgStarteddatetime doesn't have both of them (i.e. yyyy-MM-dd'T'HH:mm:ss).

Based on the JSON example, you should change the format to match exactly as provided in crgStarteddatetime:

var serializer = new DataContractJsonSerializer(obj.GetType(), new DataContractJsonSerializerSettings
 {
 DateTimeFormat = new DateTimeFormat("yyyy-MM-dd'T'HH:mm:ss")
 });

If actual JSON data of crgStarteddatetime has mixed date formats (some of the dates have yyyy-MM-dd'T'HH:mm:ss and others may have yyyy-MM-dd'T'HH:mm:ss'Z'), use K format specifier which is more flexible to handle timezone format:

var serializer = new DataContractJsonSerializer(obj.GetType(), new DataContractJsonSerializerSettings
 {
 DateTimeFormat = new DateTimeFormat("yyyy-MM-dd'T'HH:mm:ssK")
 });

• user1724708: Thank you, I greatly appreciate your help