Develop Reference

Serialization: DateTime.Now VS DateTime from database

Context: I'm serializing some data that includes a date of which I need to display milliseconds. I'm using a XmlSerializer to write an XML file. I'm taking some data from a database using a DataTable.
What I'm actually doing: I cast the date in this way
CDate(dr("MyDate")).ToUniversalTime()
But once serialized this does not includes milliseconds.
While trying some workarounds I've found out that serialize in the same way
DateTime.Now.ToUniversalTime()
does includes milliseconds.
Actual question: what should I do to include milliseconds while serializing dr("MyDate")?
Please note that answers in VB.NET or C# are both well accepted.

Have you checked, what CDate contains? For exmaple Definition of CDate shows that CDate contains only seconds, not milliseconds. When the original time in the database is stored in text format (with milliseconds) you should use DateTime.TryParseExact(...) to get the complete time value. Otherwise, when the database itself uses another DateTime-class, you should use this type directly to convert to datetime.

Parse date with time zone, skip timezone

I try to parse date from string which contains time zone information. Input string is 2014-12-17T08:05:39+00:00.
I use DateTime.Parse() method which return me 2014-12-17 09:05:39 (one hour was added). I live in UTC+1:00 (Warsaw), so .NET adopt this date to my local time.
My question is how to use the parse method while skipping time zone, for example for 2014-12-17T08:05:39+00:00 I want to get 2014-12-17 08:05:39.

I would recommend parsing it as a DateTimeOffset instead of as a DateTime. You can then get the DateTime out of that, but it separates the "parsing the data you've been given" step from the "only using the bits I want from that" step.
It's possible that there are ways to make DateTime.Parse behave the way you want using DateTimeStyles - and I'm surprised it's converting to a "local" kind automatically anyway - but using DateTimeOffset will make it clearer.
(Of course I'd really recommend using Noda Time instead, parsing to an OffsetDateTime and then getting the LocalDateTime out of that, but that's a different matter...)

If you remove the part specifying time zone in input string then it parses directly without adjusting to local time. The date.Kind is then Unspecified.
var input = "2014-12-17T08:05:39";
var date = DateTime.Parse(fixedInput);
Although this works you might want to have a look on NodaTime as well.

You should try using DateTimeOffset instead of the DateTime
DateTimeOffset result = DateTimeOffset.Parse("2014-12-17T08:05:39+00:00", CultureInfo.InvariantCulture);
it gives you : 12/17/2014 8:05:39 AM +00:00

Convert javascript date time to C#/VB.NET date time

I want to get client timezone so i'm using the code below
function filltime()
{
document.getElementById("hdnTime").value = new Date();
}
conversion
Dim time As Date = DateTime.ParseExact(hdnTime.Value,
"ddd MMM d HH:mm:ss UTCzzzzz yyyy",InvariantCulture)
I'm not getting exact value. Its showing server time only.
But hdnTime.Value contains the correct value("Mon Feb 18 14:46:49 UTC+0530 2013"). I think the problem is with conversion.
What is the problem? How can I solve?

Dates and times are a pain in 1 language, let alone when passing a value between 2.
I'd recommend serializing the JavaScript Date() object into JSON before posting it back to the server. Then de-serializing it into a C# DateTime object using a library such as JSON.NET. There's comprehensive documentation (Serializing Dates in JSON) with regards to what settings can be applied when serializing and de-serializing.
JavaScript
function filltime()
{
document.getElementById("hdnTime").value = JSON.stringify(new Date());
}
JSON isn't native to every browser, so you mean need to manually load it in, for more information you can refer to: Browser-native JSON support (window.JSON)
C# using JSON.NET
DateTime dateTime = JsonConvert.DeserializeObject<DateTime>(hdnTime.Value);

You are confusing the DateTime object with its displaying
it is normal that you see the server time because you are seeing the datetime rappresentation with your current timezone.
What you don't get is how DateTime works...
If you pass a datetime with timezone info then it will be converted to your timezone with the right offset.
If you want to pass a datetime and get it as it is than you have to remove the timezone part.
In you situation, anyway, if you need only to know the client timezone just pass it!
var d = new Date()
var n = d.getTimezoneOffset();
The getTimezoneOffset() method returns the time difference between UTC time and local time, in minutes.
For example, If your time zone is GMT+2, -120 will be returned.
For general discussion:
in my experience the best way to deal with datetime converted as string and passed between different systems, is to use the ISODATE format:
DateTime.Now.ToString("s"); //"2013-02-18T11:17:24"

Datetime formats and JSON data in C#

I'm having an issue with date/time formats in ASP.NET/C#. I have my SQL Server database set up with a PostDate field set to a type of "datetime". But it's saving the date in a strange format. I added a new row through a form and I got this as the date/time string:
2012-09-28 14:56:48.910
When it gets parsed by JSON.NET it gets even stranger. I get:
2012-09-28T14:56:48.91
The date and time are obviously correct, but how do I set things so that I can parse the date into a human-friendly way? There isn't really any code to post because the date is being added when the row is inserted. I'd like to format this as "Sept. 28, 2012 2:56 pm". How do I do that? Do I need to format the string before or after it's parsed as JSON?

That's not a "strange" format at all. The second form is ISO-8601; the first is ISO-8601 without the T. Considering the strange formats you can get in JSON, it looks like you've been let off pretty lightly!
Serialization formats aren't meant to be user-friendly, particularly - they're meant to be machine-to-machine formats.
I would hope that JSON.NET would give you a DateTime after parsing; it should only be giving you the ISO-8601 format after you've converted back to JSON.
If you've got a DateTime that you want to format for user consumption, there are all kinds of options with standard and custom format strings. Don't forget that you should respect the culture of the user, as far as possible - so make sure you're taking appropriate steps to either set the thread's current culture to be the user's one, or that you're passing the culture explicitly to DateTime.ToString etc.

You can try it in C#:
.ToString("MMM d yyyy, h:mm tt")

Change date to Universal Time Format changes my date wrongly I can't get error

I am trying to simply change the date format from the datatable to universal time format but it formats it wrongly as if I have date for August 7 it changed it to August 8 after formatting it to universal date time. My code for formatting date is,
DateVar[runs] = DateTime.Parse(Convert.ToString(output.Tables[0].Rows[runs][0])).ToUniversalTime().ToString();
Don't get in to code its correct and its a part of loop so "run" is loop and output is data set having one table I have first data in table is "Sunday, August 07, 2011 10:52 PM" and it was converted to "8/8/2011 5:52:00 AM" after implementing universal time format.
Hopes for your suggestions

Universal time isn't a format - it's a time zone, effectively. It's not clear what you're trying to do, but converting a "local" DateTime to "universal" DateTime will usually change the time. If you don't want that to happen, don't call ToUniversalTime.
It's a pity that the .NET date/time API isn't as clear as it could be - the DateTime type itself has some horrible ambiguities about it. I'm trying to improve the situation with my Noda Time project, but you will need to understand what time zones are about etc.
Personally I would suggest not using simply DateTime.Parse or just calling ToString unless you're absolutely sure that the default format is what you want. I usually call DateTime.ParseExact and specify the expected format (and usually CultureInfo.InvariantCulture unless it's a user-entered string) - and likewise I provide a format string to the ToString call.
In your code you're simply converting a string to a string - what are you attempting to accomplish? If you're just trying to change the format (e.g. to dd/MM/yyyyTHH:mm:ss) then you don't need to call ToUniversalTime but you do need to provide the format string.
I suggest you split your code out into several statements to help you debug this (and for general code clarity):
Fetch the string from the DataTable, if you really need to (if it's already a DateTime, there's no point in converting it to a string and then back again)
Parse the string (again, assuming you need to)
Perform any conversions you need to
Format the DateTime with an explicit format string
Now if any single operation is causing a problem, you can isolate it more easily.

If I run ToUniversalTime() from Greenwich it will give same time but if i do it while I live some where else it will get an offset date time object of + or - hours depending on position.