Custom JavaScriptConverter for DateTime?
I have an object, it has a DateTime property... I want to pass that object from an .ashx handler back to a webpage via AJAX/JSON... I don't want to use 3rd party controls...
when I do this:
new JavaScriptSerializer().Serialize(DateTime.Now);
I get this:
"/Date(1251385232334)/"
but I want "8/26/2009" (nevermind localization... my app is very localized, so my date formatting assumptions are not up for debate in this question). If I make/register a custom converter
public class DateTimeConverter : JavaScriptConverter
{
public override IEnumerable<Type> SupportedTypes
{
get { return new List<Type>() { typeof(DateTime), typeof(DateTime?) }; }
}
public override IDictionary<string, object> Serialize(object obj, JavaScriptSerializer serializer)
{
Dictionary<string, object> result = new Dictionary<string, object>();
if (obj == null) return result;
result["DateTime"] = ((DateTime)obj).ToShortDateString();
return result;
}
public override object Deserialize(IDictionary<string, object> dictionary, Type type, JavaScriptSerializer serializer)
{
if (dictionary.ContainsKey("DateTime"))
return new DateTime(long.Parse(dictionary["DateTime"].ToString()), DateTimeKind.Unspecified);
return null;
}
}
then I get this result (since the return value of the custom serialize method is a dictionary):
{"DateTime":"8/27/2009"}
so now in my Javascript, instead of doing
somePerson.Birthday
I have to do
somePerson.Birthday.DateTime
or
somePerson.Birthday["DateTime"]
how can I make the custom converter return a direct string so that I can have clean Javascript?
JavaScriptSerializer can definitely do what you desire.
It's possible to customize the serialization performed by JavaScriptSerializer for any type by creating a custom converter and registering it with the serializer. If you have a class called Person, we could create a converter like so:
public class Person
{
public string Name { get; set; }
public DateTime Birthday { get; set; }
}
public class PersonConverter : JavaScriptConverter
{
private const string _dateFormat = "MM/dd/yyyy";
public override IEnumerable<Type> SupportedTypes
{
get
{
return new[] { typeof(Person) };
}
}
public override object Deserialize(IDictionary<string, object> dictionary, Type type, JavaScriptSerializer serializer)
{
Person p = new Person();
foreach (string key in dictionary.Keys)
{
switch (key)
{
case "Name":
p.Name = (string)dictionary[key];
break;
case "Birthday":
p.Birthday = DateTime.ParseExact(dictionary[key] as string, _dateFormat, DateTimeFormatInfo.InvariantInfo);
break;
}
}
return p;
}
public override IDictionary<string, object> Serialize(object obj, JavaScriptSerializer serializer)
{
Person p = (Person)obj;
IDictionary<string, object> serialized = new Dictionary<string, object>();
serialized["Name"] = p.Name;
serialized["Birthday"] = p.Birthday.ToString(_dateFormat);
return serialized;
}
}
And use it like this:
JavaScriptSerializer serializer = new JavaScriptSerializer();
serializer.RegisterConverters(new[] { new PersonConverter() });
Person p = new Person
{
Name = "User Name",
Birthday = DateTime.Now
};
string json = serializer.Serialize(p);
Console.WriteLine(json);
// {"Name":"User Name","Birthday":"12/20/2010"}
Person fromJson = serializer.Deserialize<Person>(json);
Console.WriteLine(String.Format("{0}, {1}", fromJson.Name, fromJson.Birthday));
// User Name, 12/20/2010 12:00:00 AM
Here's an enhancement for the accepted answer.
Using generics, passing a type and using reflection to determine the datetime properties.
public class ExtendedJavaScriptConverter<T> : JavaScriptConverter where T : new()
{
private const string _dateFormat = "dd/MM/yyyy";
public override IEnumerable<Type> SupportedTypes
{
get
{
return new[] { typeof(T) };
}
}
public override object Deserialize(IDictionary<string, object> dictionary, Type type, JavaScriptSerializer serializer)
{
T p = new T();
var props = typeof(T).GetProperties();
foreach (string key in dictionary.Keys)
{
var prop = props.Where(t => t.Name == key).FirstOrDefault();
if (prop != null)
{
if (prop.PropertyType == typeof(DateTime))
{
prop.SetValue(p, DateTime.ParseExact(dictionary[key] as string, _dateFormat, DateTimeFormatInfo.InvariantInfo), null);
}
else
{
prop.SetValue(p, dictionary[key], null);
}
}
}
return p;
}
public override IDictionary<string, object> Serialize(object obj, JavaScriptSerializer serializer)
{
T p = (T)obj;
IDictionary<string, object> serialized = new Dictionary<string, object>();
foreach (PropertyInfo pi in typeof(T).GetProperties())
{
if (pi.PropertyType == typeof(DateTime))
{
serialized[pi.Name] = ((DateTime)pi.GetValue(p, null)).ToString(_dateFormat);
}
else
{
serialized[pi.Name] = pi.GetValue(p, null);
}
}
return serialized;
}
public static JavaScriptSerializer GetSerializer()
{
JavaScriptSerializer serializer = new JavaScriptSerializer();
serializer.RegisterConverters(new[] { new ExtendedJavaScriptConverter<T>() });
return serializer;
}
}
Usage is simple:
JavaScriptSerializer serialiser = ExtendedJavaScriptConverter<Task>.GetSerializer();
Hope that helps someone.
There is actually a nice clean way to do this without knowing the wrapper type or even needing a wrapper object.
You use JavaScriptConverter to convert your object to a Uri that also implements IDictionary. JavaScriptSerializer will serialize this as a string.
This hack is described here:
http://blog.calyptus.eu/seb/2011/12/custom-datetime-json-serialization/
链接地址: http://www.djcxy.com/p/1264.html上一篇: “正确”的JSON日期格式