I have made a function to convert a textbox value to date.
I want to store the converted date in a datetime field in my business object with only date and not time like in format(yyyy-MM-dd)
My function is returning date along with time
public static DateTime ExtractDate(string myDate)
{
DateTime result = DateTime.MinValue;
if (myDate != null)
{
try
{
result=DateTime.Parse(myDate, new System.Globalization.CultureInfo("en-CA", true), System.Globalization.DateTimeStyles.AdjustToUniversal).ToString("yyyy-MM-dd");
}
catch (Exception)
{
throw new ApplicationException("DateTime conversion error");
}
}
return (result.Date);
}
DateTime itself always includes a time, in the case when you're setting it equal to a 'date' then the time will be 00:00:00. When it comes to displaying the string you'll need to use a format string that includes just the date part.
Just use:
result = DateTime.Parse(...).Date;
Therre's no need to convert the date/time back to a string first. The resulting DateTime will just be midnight on the relevant date.
I see that you're adjusting to universal time - you need to be aware that that may change the date. Dates are inherently local - i.e. my August 25th may well start at a different time to yours due to time zones. Alternatively, you could parse it as if it were in UTC to start with and treat it that way. You just need to be careful with what you're doing - you could run into problems where midnight doesn't exist on some days in some time zones. (Been there, done that...)
I would also suggest using DateTime.TryParseExact and specifying the input format. In particular, if you only expect users to enter dates, then specify appropriate date formats. Using TryParseExact instead of ParseExact means you don't have to catch an exception to notice that the user hasn't entered a valid date.
EDIT: Just to clarify: .NET doesn't have a type representing "just a date". Noda Time does, but that's not ready for production yet :( Normally you'd just use a DateTime and ignore the time part.
Date property returns a DateTime with time set to "00.00:00". You can not remove time from a DateTime, you can avoid to show it in the GUI using string.Format("d", yourDate).
I would change the method and return a string instead of a DateTime, because there is always time attached (therefor also the name DateTIME ;-))
If you return a string, you can do something like:
return DateTime-object.ToString("yyyy/MM/dd");
Good luck!
Related
I'm trying to get ahold of this timezone issue we are having. We would like to store all DateTimes in UTC, and then convert the DateTime to the user's timezone.
We decided to use NodaTime for this, as it seems like the right approach. However, we are experiencing an issue with it.
This is how we convert the DateTime to UTC (note - I hardcoded the usersTimeZone for now):
public static DateTime ConvertLocaltoUTC(this DateTime dateTime)
{
LocalDateTime localDateTime = LocalDateTime.FromDateTime(dateTime);
IDateTimeZoneProvider timeZoneProvider = DateTimeZoneProviders.Tzdb;
var usersTimezoneId = "Europe/Copenhagen";
var usersTimezone = timeZoneProvider[usersTimezoneId];
var zonedDbDateTime = usersTimezone.AtLeniently(localDateTime);
var returnThis = zonedDbDateTime.ToDateTimeUtc();
return zonedDbDateTime.ToDateTimeUtc();
}
And here is how we convert it back:
public static DateTime ConvertUTCtoLocal(this DateTime dateTime)
{
Instant instant = Instant.FromDateTimeUtc(dateTime);
IDateTimeZoneProvider timeZoneProvider = DateTimeZoneProviders.Tzdb;
var usersTimezoneId = "Europe/Copenhagen"; //just an example
var usersTimezone = timeZoneProvider[usersTimezoneId];
var usersZonedDateTime = instant.InZone(usersTimezone);
return usersZonedDateTime.ToDateTimeUnspecified();
}
However, when we convert it back to local time, it throws an exception:
Argument Exception: Invalid DateTime.Kind for Instant.FromDateTimeUtc
at the first line of ConvertUTCtoLocal().
An example of the DateTime could be: "9/18/2017 5:28:46 PM" - yes this has been through the ConvertLocalToUTC method.
Am I providing an incorrect format? What am I doing wrong here?
The exception you show:
Argument Exception: Invalid DateTime.Kind for Instant.FromDateTimeUtc
Is thrown from this code:
Instant instant = Instant.FromDateTimeUtc(dateTime);
It means that dateTime.Kind needs to be DateTimeKind.Utc to be convertible to an Instant, and for whatever reason it is not.
If you look at the result of your ConvertLocaltoUTC method, you'll find that it does have .Kind == DateTimeKind.Utc.
So, the problem lies elsewhere in your code, wherever you created the dateTime you're passing in to ConvertUTCtoLocal.
You may find the solution could be any of the following:
You might need to call DateTime.SpecifyKind to set the kind to UTC, but be careful to only do this when your values are actually UTC and it's just not setting the kind. For example, use this when loading a UTC-based DateTime from a database.
You might need to call .ToUniversalTime(), but be careful to only do this if the machine's local time zone is relevant to your situation. For example, do this in desktop or mobile apps where a UI control is picking a date, but you meant it to mean UTC instead of local time.
You might need to change how you parse strings into DateTime values, such as by passing DateTimeStyles.RoundTripKind to a DateTime.Parse call (or any of its variants. For example, do this if you are reading data from text, csv, etc.
If you want to avoid having to decide, don't write functions that take DateTime as input or give DateTime as output. Instead, use DateTimeOffset, or use Noda-Time types like Instant, LocalDateTime, etc. as early as possible.
This is what worked for me:
Instant instant = Instant.FromDateTimeUtc(DateTime.SpecifyKind(datetime, DateTimeKind.Utc));
I am getting this error while in Debug though the ToString() is executed:
A UTC DateTime is being converted to text in a format that is only
correct for local times. This can happen when calling
DateTime.ToString using the 'z' format specifier, which will include a
local time zone offset in the output. In that case, either use the 'Z'
format specifier, which designates a UTC time, or use the 'o' format
string, which is the recommended way to persist a DateTime in text.
This can also occur when passing a DateTime to be serialized by
XmlConvert or DataSet. If using XmlConvert.ToString, pass in
XmlDateTimeSerializationMode.RoundtripKind to serialize correctly. If
using DataSet, set the DateTimeMode on the DataColumn object to
DataSetDateTime.Utc.
public static string ToInterfaceString(this DateTime value)
{
return value != DateTime.MinValue ? value.ToString("yyyy-MM-ddTHH:mm:sszzz") : string.Empty;
}
In the app that I've just starting to work on it is used this format in many places. So what should I do in fact? Replace zzz with Z?
Update 1:
the DateTime that is passed to my extension is initiated to:
DateTimeCreated = DateTime.UtcNow;
Weird thing is that if I pass to this extension some other DateTime objects I don't receive any error/warning.
It's a green warning only.
So - as you seem to know what you are doing - you can just comprehend the message (which is correct) and mark the checkbox to Ignore this warning in the future.
As the DateTimeInvalidLocalFormat error explains, the conversion of the date value to string with your defined date format is not usable with DateTime which have the property Kind set to 'Utc'. Even though this error is just a warning and your code should still work, the resulting date string you will get after such operation will be incorrect. This means that if you convert your date to string and will try to parse it again to DateTime, the resulting DateTime value will be different from your original DateTime value. The difference will be as large as your time zone offset from the UTC time is. This is a serious error and should not be ignored especially if your local time does not match the UTC time.
Example:
In this example I assume that the local time zone is 2 hours ahead of UTC time.
DateTime yourLocalTime = DateTime.Now; // => 2020-05-15 08:00:00 => yourLocalTime.Kind = Local
DateTime yourTimeInUTC = DateTime.UtcNow; // => 2020-05-15 06:00:00 => yourTimeInUTC.Kind = Utc, note hours, e.g. 6 vs 8
string dateFormat = "yyyy-MM-ddTHH:mm:sszzz";
string testDateLocal = yourLocalTime.ToString( dateFormat ); // 2020-05-15T08:00:00+02:00 - This is correct date and time
string testDateUtc = yourTimeInUTC.ToString( dateFormat ); // 2020-05-15T06:00:00+02:00 - This date and time is 2 hours behind your actual date and time
To print the date and time string correctly using your date format you have to first convert your UTC date and time to the local date and time:
string testDateUtc2 = yourTimeInUTC.ToLocalTime().ToString( dateFormat ); // 2020-05-15T08:00:00+02:00 - This is correct date and time
To fix your code you should add conversion to the local time in your method:
public static string ToInterfaceString(this DateTime value)
{
return value != DateTime.MinValue ? value.ToLocalTime().ToString("yyyy-MM-ddTHH:mm:sszzz") : string.Empty;
}
You could also print UTC date and time instead of local date and time by replacing date format specifiers 'zzz' to 'Z'. However, in this case you will have a similar issue with conversion in case the DateTime passed to your method is not in UTC Kind, but e.g. in Local Kind and therefore, you have to always convert it to UTC before generating the string:
public static string ToInterfaceString(this DateTime value)
{
return value != DateTime.MinValue ? value.ToUniversalTime().ToString("yyyy-MM-ddTHH:mm:ssZ") : string.Empty;
}
Printing of date and time without doing conversion can also be done by using date format specifier 'o', but then the generated date string format will differ based on supplied DateTime Kind and this date format also includes the milliseconds.
public static string ToInterfaceString(this DateTime value)
{
return value != DateTime.MinValue ? value.ToString("o") : string.Empty;
}
This exception is thrown and caught internally inside of ToString() method so the application will continue to run further. It's the only debugger who shows this.
It might initially look like a warning which is visible when debugging only but in fact, this code will generate valid results only in case when your computer time zone is UTC (seems there will be no internal exception in this case too). If your local time zone offset is, for example, UTC+02 than the result of:
new DateTime(2020,7,30,11,22,33, DateTimeKind.Utc).ToString(#"yyyy-MM-dd\THH:mm:sszzz");
on your computer will be "2020-07-30T11:22:33+02:00" which doesn't make sense because the result obviously should have UTC offset as 00:00.
Also, of course, such internal exceptions is a bad thing for control flow and might affect your app performance if this occurs too often.
To avoid invalid .ToString() results and also internal exceptions you can just create DateTimeOffset from given DateTime and invoke .ToString() for it. So the code:
new DateTimeOffset(new DateTime(2020,7,30,11,22,33, DateTimeKind.Utc)).ToString(#"yyyy-MM-dd\THH:mm:sszzz");
will give expected result "2020-07-30T11:22:33+00:00" for any local time zone.
Another suggestion is to use the "K" custom format specifier which gives the correct results for both DateTime and DateTimerOffset.
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
I'm currently developing an application to function as a todo - list and i was wondering how do i accept a Value from a date time box, but only use the value of the date, or the value of the time. I'm currently doing it like this.
DateTime ted = appointmentDateTimeDate.Value; //The date
DateTime at = appointmentDateTimeTime.Value; //The time
should i be doing this another way?
Use DateTime.Date property for date, and DateTime.TimeOfDay for time:
DateTime ted = appointmentDateTimeDate.Date; //The date
TimeSpan at = appointmentDateTimeTime.TimeOfDay; //The time
The BCL doesn't really separate dates and times nicely.
If you're happy to take a new external dependency, I'd like to plug my Noda Time library, which will let you separate things out clearly into LocalDate and LocalTime. To perform the conversion from a date/time picker you'd probably use:
var dateAndTime = LocalDateTime.FromDateTime(appointmentDateTimeDate.Value);
LocalDate date = dateAndTime.LocalDate;
LocalTime time = dateAndTime.LocalTime;
Like others pointed out a DateTime always has both a date and a time component. So although it's possible to save both independently using two DateTime, in most cases it's recommendable to save both together in a single DateTime instance.
You should see if you really need both values separated or if your application could combine both in one property, which will make things easier.
A DateTime value ALWAYS contains both the date and the time, whether you use both or not.
You can use the .Date property of a DateTime to get "just the date". it will still have a time value, but the time value will be midnight. You can also use the .TimeOfDay property to get the time portion, which will be a TimeSpan indicating the number of ticks since midnight.
I'm taking a leap here and assuming you're trying to set the date with one control an d the time with another in the UI. Here's a sample of some code we use to do this using an Ajax CalendarExtender attached to a textbox and a custom TimePicker control.
DateTime dt;
try
{
dt = Convert.ToDateTime(txtViewDate.Text).AddHours(txtViewTime.Hour).AddMinutes(txtViewTime.Minute);
if (txtViewTime.AmPm == MKB.TimePicker.TimeSelector.AmPmSpec.PM)
{
dt = dt.AddHours(12);
}
System.Diagnostics.Debug.WriteLine(dt.ToString());
}
catch (Exception)
{
// abort processing
return;
}
I am receiving some data into a variable of type object. In certain cases this data are date values. For that data, I would like to convert this to a string and return it in the same format as it was passed. In some cases, the object could be a datetime, in others a date only or time only values.
As soon as I convert the object to a date or a string, it is obviously given a time of midnight which in my scenario may be a valid time (so I cannot test to see if the time is midnight in which case I could deduce that it would have been a date only date value, nor can I use regex on it as there will always be a time element).
Intellisense shows me it correctly, ie in the format I am wishing to return the value.
Is there an easy way to achieve this (hopefully without using reflection)
Many thx
Simon
Your question is a little unclear but I think you're looking for something like this:
DateTime result;
if (DateTime.TryParse(value, out result))
{
// use result here
}
In the above code value is a string that represents the data coming in. The code will only enter the if block if the string is a valid DateTime. At which point you can do the processing you need on it.
Im not sure i understand the question but i would recommend you to take a look at this conversion example on MSDN, and see the Documentation of the DateTime Structur it contains a lot of Conversion/Formatting Methods i hope it helps.
There are many way to do formatting on the datetime and one of the simple way is fetch the data from the required table in the desired format. Like here you need to display the date and if you your format is dd/MM/yyyy then try this
select Convert(varchar(10),StartDate,103) as StartDateformat from table where filtername=#filtername
use this link to find other format Cast and Convert
From local variable to DateTime Conversion
DateTime todateformat = Convert.ToDateTime(txttodate.Text.Trim());
From DateTime to local variable Conversion in specific format
string startdate = todateformat.ToString("dd/MM/yyyy hh:mm:ss");