serializing dates correctly with javascript serializer in asp.net mvc3

Question

i am experimenting with backbone javascript after seeing the Tekpub MVC3 screencasts by Rob Connery

i like his Massive database access, but as soon as it is getting a bit more complex than a video can possibly show you.

i added extra fields to my database, being datetime fields. however, this javascript serializer, converts them into strings

public string toJson(dynamic content) {
  var serializer = new JavaScriptSerializer();
  serializer.RegisterConverters(new JavaScriptConverter[] { new ExpandoObjectConverter() });
  var json = serializer.Serialize(content);
  return json.ToString();
}

this makes a datetime from this: {19/10/2011 1:58:27} into this: "19/10/2011" (*values taken from the quickwatch window on runtime..., basicly comes down to a loss in precision and it now being a basic string.

after backbone pushes that back to the server (on a model.save() call), i try to update the model like Rob does:

[HttpPut]
public ActionResult Edit()
{
  var model = SqueezeJson();
  model.UpdatedAt = DateTime.Now;
  _movies.Update(model, model.Id);
  return CmoJSON(model);
}

for the SqueezeJson function, check his source

resulting in an error like this:

Arithmetic overflow error converting expression to data type datetime.

i kind of expected this to happen since i noticed the dates being dumped into strings, i had no idea how it would go back into a date time using massive.

has anyone worked with massive and dates, in a context like this (serializing to and from json)? i know the problem isn't necessarily massive itself, it's the json serializiation that dumbs it down into a string with loss of data, and doesn't return it to a proper date.

but still, maybe someone has a better way of doing this... any idea's are welcome...

Answer 1

I have encountered the same question with you.

You can change Serialize method in ExpandoObjectConverter like:

public override IDictionary<string, object> Serialize(object obj, JavaScriptSerializer serializer)
{
    ExpandoObject expando = (ExpandoObject) obj;

    if(expando!=null)
    {
        Dictionary<string,object> result = new Dictionary<string, object>();
        foreach (KeyValuePair<string, object> item in expando)
        {
            var value = item.Value ?? "";
            if (value is DateTime)
                result.Add(item.Key, ((DateTime) value).ToString("yyyy.MM.dd"));
            else
            {
                result.Add(item.Key, value.ToString());
            }
        }

        return result;
    }

    return new Dictionary<string, object>();
}