Agfdhyk

We have a API service that we are updating and we converted some date objects from strings to DateTime objects. In the old code we tested the string if it would parse to a data time or not. If it was a bad formatted string, it would assign DateTime.Min and continue on. Now customers are sending in bad dates and it blows up since the serialization happens outside our code (MVC Controller). I am trying to find some way that when serializing a DateTime object, if it can not parse it, it just returns DateTime.Min instead of blowing up the call.

Here is the response from the API Call.

{

  "date": [

    "Could not convert string to DateTime: Invalid Date. Path 'date', line 3, position 24."

  ]

}

===== UPDATE =====

I finally found somewhere that recommended a custom JsonConverter. I finally got something that works, but there is little out there so if there is something I could do better I am all ears.

Custom Converter

  public class DateConverter : JsonConverter

  {

    public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)

    {

    }



    public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)

    {

      try

      {

        return DateTime.Parse(reader.Value.ToString());

      }

      catch (Exception ex)

      {

        return DateTime.MinValue;

      }

    }



    public override bool CanConvert(Type objectType)

    {

      return objectType == typeof(DateTime);

    }

  }

DTO Class

public class Request

  {



    [JsonConverter(typeof(SafeDateConverter))]

    public DateTime Date { get; set; }

  }

Another approach introduce another property on deserialized class of type DateTime? and leave original string property as it is.

public class Request

{

    public string Date { get; set; }



    private DateTime? _parsedDate;

    [JsonIgnore]

    public DateTime? ParsedDate 

    { 

        get { return _parsedDate; } 

        set

        {

            if (DateTime.TryParse(value, out DateTime parsed)

            {

                _parsedDate = parsed;

                return;

            }



            _parsed = null;

        }

    }       

}

But having custom serializer looks better, because you need change nothing in the code which already uses deserialized object.

Suggestion:

Do not use try ... catch for serializing bad formatted dates, there is DateTime.TryParse method which will do this without throwing exceptions.

And if it is not late, you can use Nullable<DateTime> instead of having DateTime.Min as "not existing" value.