C# change date between different formats - c#

I want to know if there's a way to change the date format depending on the users local date format setting. The date I will store in the DB it's YYYY-MM-DD but the users have different formats, like DD-MM-YYYY or DD.MM.YYYY. What is a clean, elegant way to ensure that my application always retrives the date in local date format, and SQL server always receives the date in YYYY-MM-DD to be stored.

in the DB it's YYYY-MM-DD
No. If you do it right the storage in the Db does not have a format. It is stored, for example, as a number.
What is a clean, elegant way to ensure that my application always retrives the date in local date format
Your application receives it as a binary value too. You have to think about format every time it becomes a string.
in local date format
For that you could rely on the machine configuration: datevalue.ToString().
But usually you want to take control: datevalue.ToString(specificCultureInfo)

You should always save the date in a datetime object. To parse a date you can use DateTime.TryParseExcact when you know the date format and TryParse when you want to use your users prefrence. However it whould be nicer to use dedecated date controls to get a date from the user.

A DateTime object doesn't have a format. You're probably talking about the string representation of the date.
You can return the date as a string using the user's respective culture settings by calling DateTime.ToShortDateString()
DateTime date = new DateTime(2012, 01, 01);
string dateStringInCurrentCultureFormat = date.ToShortDateString();

Related

Format Localized DateTime C#

I want to format localized date into format. e.g yyyyMMdd OR ddMMyyyy OR MMddyyyy based on system date format. Below is what I have tried and it is working , but need efficient way to do same.
DateTime.Now.ToLocalTime().Date.ToString().Replace("/","").Replace(":","").Replace(" ","").Replace("-","")
You can use the ToString overload(read also):
DateTime.Now.ToLocalTime().ToString("yyyyMMdd")
(why you think you need ToLocalTime here? Now always returns the local time)
cant use .ToString("yyyyMMdd") because i need different result
depending on what my system date format is. if system date time is
dd-MM-yyyy i want ddMMyyyy, if its yyyy-MM-dd then expected result is
yyyyMMdd
Then you either stick with your current approach or use something like this:
DateTime.Now.ToString("d").Replace(DateTimeFormatInfo.CurrentInfo.DateSeparator, "")

How to check for current culture in my ado.net code?

I am trying to parse a date that is coming from a source as "02/11/2013"
In my application, I set the user's culture to either en-CA or en-FR, with their date format's being "dd/MM/yyyy" or "M/d/yyyy"
If I parse the date, and pass in the format, will this work or does it depend on which format I saved to the database?
if (DateTime.TryParseExact(dateString, Thread.CurrentThread.CurrentCulture.DateTimeFormat.ShortDatePattern, null, System.Globalization.DateTimeStyles.None, out dtResult))
{
dt = dtResult;
}
I can think properly right now so I need some clarification.
Me passing in the format of "dd/MM/yyyy" or "M/d/yyyy", does this format the date no matter what format the source is in, or is it me telling the datetime parse that the source will be in this format so use this?
What I am weary of is that someone is saving to the db in one format, and then a french person wants to read the date and their own format (yes I should be storing in utc).
ADO.NET is strongly typed; there are well known types for storing most data. In the case of dates, that would be DateTime in .NET and datetime in most database systems. If you ever need to worry about culture, then you're already doing it wrong, because you are passing the data around as a string rather than as a DateTime / datetime.
This then renders your concern here redundant:
What I am weary of is that someone is saving to the db in one format, and then a french person wants to read the date and their own format (yes I should be storing in utc).
because a DateTime / datetime has no notion of format - it is simply a date/time value. Any UI presentation / parsing of string data should be completely isolated and specific to the UI. Beyond the UI code you should (when talking about dates/times) be using DateTime / datetime exclusively.
Similarly, when storing an integer you should be using int.
If the date is stored only as "02/11/2013" without any other culture identifying information there is no way for you to know how to properly interpret it! You are absolutely right being worried that somebody with a en-FR culture might save a date to the database as "02/11/2013" meaning the 2nd of November and then somebody with an en-US culture might read that date and interpret it as the 11th of February.
You should only pass the current culture if you know that is relevant, meaning that you know the date string was generated using that culture.
A better approach is to NOT store dates like that in the first place. It's best to store the date in a format that includes timezone as well as format information such as the Internet Date/Time RFC 3339 format.
Or, if you can't, at least make sure to take the date and always convert it to say en-US culture before storing in the database and than pass that culture to the DateTime.Parse when reading from the database.
The .NET XML serialization code for dates can come in handy when serializing/deserializing dates in RFC 3339 format. See this SO post for more info..

getting hour part and time-zone part from datetime

I had a string in config file, defining date time with time zone.
I am not able to get this value, while reading values from config file.
In config file:
Setting name="abcdefgh" value="2012-08-10T22:00:00-08:00"
In C#, I am reading this as follows:
DateTime StartDate;
StartDate = DateTime.ParseExact(RoleEnvironment.GetConfigurationSettingValue("abcdefgh"), "yyyy-MM-dd HH:mm:ss", null);
Configuration.Instance.abcdefgh= StartDate;
In start date, i am getting 11 Aug, 2012 11:30:00, with no time zone.
I want to read it as it is. also tell, if my format of writing datetime in config file is correct
MSDN link to DateTimeOffset.
Use DateTimeOffset whenever you are referring to an exact point in
time. For example, use it to calculate "now", transaction times, file
change times, logging event times, etc. If the time zone is not
known, use it with UTC. These uses are much more common than the
scenarios where DateTime is preferred, so this should be considered
the default.
var date = DateTimeOffset.Parse("2012-08-10T22:00:00-08:00");
date.Offset // -08:00:00, offset from Coordinated Universal Time (UTC)
date.DateTime // 10/08/2012 22:00:00,
DateTime doesn't keep information about timezone. To parse the string and keep information about timezone - you should use DateTimeOffset structure.
Use the DateTimeOffset structure (and DateTimeOffset.ParseExact) if you want to store timezone information.
Your ParseExact format also doesn't quite match the setting value: it should have a zz at the end for the timezone information. You can also use DateTimeOffset.Parse since your setting string is in a standard format.
It's a standard format, so the ParseExact isn't needed, try:
StartDate = DateTime.Parse(RoleEnvironment.GetConfigurationSettingValue("abcdefgh"));
I substituted the hard-coded value you provided and got the correct result for my timezone (GMT-4) as
8/11/2012 2:00 AM
Note: as others mentioned, the timezone is not retained, so you will get the correct localized time corresponding to whatever timezone information was in the string, but you won't be able to find out what timezone that was. The DateTime.Kind property will reflect that it's a local time.

.NET Save DateTime and completely ignore timezone

Maybe the answer is so obvious, I'm not seeing it, but I have a question that I'll risk asking anyway.
I want to allow users of a .NET Web application to enter a date/time, store it in an Oracle database, and no matter which timezone they are in, it always displays as the raw, original version as typed in by the user. So if one user in California enters 2PM and another in Maryland enters 2PM, they would both show as 2PM to a user in Japan. Two types of clients are possible, a web user and a windows client user (connected via web service).
Think of it like I want to completely break all timezone smarts that most applications worry about.
I don't want to save as a string though. I want a datetime that I can add/remove hours and minutes from.
Edit:
This was basically the exact problem I was having.
You should always store DateTime in UTC format (universal). When you display it you can choose which ever timezone you wish, in your case this can be fixed for all users, rather than based on location.
// when recording date time
DateTime utcDateTime = DateTime.UtcNow;
// parse DateTime back out from string
DateTime utcDateTime = DateTime.SpecifyKind(DateTime.Parse(dateStr),
DateTimeKind.Utc);
// localized DateTime
DateTime localDate = utcDateTime.ToLocalTime();
// fixed DateTime based on timezone
string timeZoneKey = "New Zealand Standard Time";
TimeZoneInfo timeZone = TimeZoneInfo.FindSystemTimeZoneById(timeZoneKey);
DateTime nzlocalDate = TimeZoneInfo.ConvertTimeFromUtc(utcDateTime, timeZone);
This takes into account things like day-light savings which can trip you up if start saving localized dates.
If you just store the DateTime as entered/picked by the user then it will be stored as just that. There will be time zone informations stored in it, but you are in control of what you do with it.
For example, when you want to output it to the screen/file etc. you will need to format it to a string. If you use this ToString overload with CultureInfo.InvariantCulture then this should ignore the current culture and output the date as is:
DateTime date = DateTime.Now;
string output = date.ToString("d", CultureInfo.InvariantCulture);
Other operations will require different handling, but you will need to specify what happens in each case.
I had a time sensitive fix and the SpecifyKind did not allow me to make proper TimeSpan comparisons. In my situation, the quickest solution was to simply remove the Hours, Minutes, and Seconds from the time, as the DateTime I was comparing with was at midnight (00:00:00),
DateTime eventDateTime = (DateTime)row["event_date"];
eventDateTime = eventDateTime.AddHours(-1 * eventDateTime.Hour).AddMinutes(-1 * eventDateTime.Minute).AddSeconds(-1 * eventDateTime.Second);
If you really want discard time zone:
public static DateTime WithoutTimeZone(this DateTime dateTime)
{
if (dateTime.Kind != DateTimeKind.Unspecified)
return new DateTime(dateTime.Ticks, DateTimeKind.Unspecified);
return dateTime;
}

DateTime Format Problem To Get Same Format

I have some questions about using datetime format.
In one part of project,client pc send their datetime to server.
we need to get those datetime in same format like dd/MM/yyyy.
However,client pc use variety of date format,so,they send
variety of datetime format like this.for eg,
dd-MM-yyyy,dd/MM/yyyy,MM-dd-yyyy,MM/dd/yyyy
How can I solve this problem?
The absolute best way is to not treat date values as strings. They should to the greatest extent possible be treated as DateTime values. When doing that, all issues related to formatting disappears. If you have a client where the user enters date format in their local style, convert it to a DateTime directly after input, and then send the DateTime value into the system.
If you still need to exchange date information in string format, always stick to a standardized format (such as ISO 8601).

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