.NET Core - 转换读取JSON文件的日期

Question

is there any way to convert date read from JSON file? Exemplary record from my file is:

{
    "UserID": 73274,
    "Created": "17-03-2018 06:35",
    "Office": "Washington"
},

What I am doing is importing JSON file and save its content to database. The problem is, when date is in DD-MM-YYYY hh:ss format, it simply doesn't work. But when date is in YYYY-MM-DDThh:mm:ss format, everything is fine. How to parse date to another format after reading this file and execute following operations on file with parsed date?

Part of my controller responsible for this operations is:

if (file.ContentType == "application/json")
{
    try
    {
        using (var reader = new StreamReader(file.OpenReadStream()))
        {
            content = reader.ReadToEnd();
        }
     }
     catch
     {
         return BadRequest(Messages.fileNotChosen);
     }
     try
     {
         userObjects = JsonConvert.DeserializeObject<List<UserImportModel>>(content);
     }
     catch
     {
         return BadRequest();
     }
 }

When date format is YYYY-MM-DDThh:mm:ss , userObjects is properly counted and controller moves to part where I execute adding to database. When date format is DD-MM-YYYY hh:ss , userObjects = 0 and controller moves to catch, which then returns BadRequest().

EDIT: Code of UserImportModel class:

public class UserImportModel
{

    public string UserID { get; set; }

    [DataType(DataType.Date)]
    [DisplayFormat(DataFormatString = "{0:dd/MM/yyyy}")]
    public DateTime Created { get; set; }

    public string Office { get; set; }

}

Answer 1

If you need to deserialize date in different formats, you have to create a custom JsonConverter :

public class MultiFormatDateTimeConverter : JsonConverter
{
    private List<string> formats;

    public MultiFormatDateTimeConverter(List<string> formats)
    {
       this.formats = formats;
    }

    public override bool CanConvert(Type objectType)
    {
        return objectType == typeof(DateTime);
    }

    public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
    {
        string dateString = (string)reader.Value;

        foreach (string format in formats)
        {
            if (DateTime.TryParseExact(dateString, format, CultureInfo.InvariantCulture, DateTimeStyles.None, out DateTime date))
            {
                return date;
            }
        }
        throw new JsonException("Unable to parse \"" + dateString + "\" as a date.");
    }

    public override bool CanWrite
    {
        get { return false; }
    }

    public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
    {
        throw new NotImplementedException();
    }
}

Usage example:

var settings = new JsonSerializerSettings();
settings.DateParseHandling = DateParseHandling.None;
settings.Converters.Add(new MultiFormatDateTimeConverter(new List<string> { "DD-MM-YYYY hh:ss", "YYYY-MM-DDThh:mm:ss" }));

userObjects = JsonConvert.DeserializeObject<List<UserImportModel>>(content, settings);

Answer 2

JSON.Net uses the Standard 8601 to represent Date-Time . The extended format for a complete date-time expression is: "YYYY-MM-DDTHH:MM:SS". The JSON.Net "Deserializer" method ( DeserializeObject ) is overloaded for acceptting custom formatters, you can use de IsoDateTimeConverter specifying in the DateTimeFormat property the format of your string "dd"

userObjects = JsonConvert.DeserializeObject<List<UserImportModel>>(content, 
                   new IsoDateTimeConverter { DateTimeFormat = "dd-MM-yyyy hh:mm:ss" });

Another alternative is to use a regular expresion to replace all bad formed ISO Dates in your JSON string before calling the DeserializeObject method .