For example, using a date and time control, the user selects a date and time, such that the string representation is the following:
"6-25-2012 12:00:00 PM"
It so happens that this user is in the EST time zone. The string is passed to the server, which translates it into a .NET DateTime object, and then stores it in SQL Server in a datetime column.
Clearly something needs to be added to the original datetime string before its passed to the server to be persisted. What is the recommended way of doing this?
Date constructor to parse a string. The behavior and supported formats vary wildly per browser and locale. Here are just some of the default behaviors if you use the
Date object directly.
If you must come from a string, try using a standardized format such as ISO8601. The date you gave in that format would be
Also, be careful about what you are actually meaning to represent. Right now, you are passing a local date/time, saving a local/date/time, and returning a local date/time. Along the way, the idea of what is "local" could change.
In many cases, the date/time is intended to represent an exact moment in time. To make that work, you need to convert from the local time entered to UTC on the client. Send UTC to your server, and store it. Later, retrieve UTC and send it back to your client, process it as UTC and convert back to local time. You can do all of this easily with moment.js:
// I'll assume these are the inputs you have. Adjust accordingly. var dateString = "6-25-2012"; var timeString = "12:00:00 PM"; // Construct a moment in the default local time zone, using a specific format. var m = moment(dateString + " " + timeString, "M-D-YYYY h:mm:ss A"); // Get the value in UTC as an ISO8601 formatted string var utc = m.toISOString(); // output: "2012-06-25T19:00:00.000Z"
On the server in .Net:
var dt = DateTime.Parse("2012-06-25T19:00:00.000Z", // from the input variable CultureInfo.InvariantCulture, // recommended for ISO DateTimeStyles.RoundtripKind) // honor the Z for UTC kind
Store that in the database. Later retrieve it and send it back:
// when you pull it from your database, set it to UTC kind var dt = DateTime.SpecifyKind((DateTime)reader["yourfield"], DateTimeKind.Utc); // send it back in ISO format: var s = dt.ToString("o"); // "o" is the ISO8601 "round-trip" pattern.
// construct a moment: var m = moment("2012-06-25T19:00:00.000Z"); // use the value from the server // display it in this user's local time zone, in whatever format you want var s = m.format("LLL"); // "June 25 2012 12:00 PM" // or if you need a Date object var dt = m.toDate();
See - that was easy, and you didn't need to get into anything fancy with time zones.
Here, I think this is what you are looking for: How to ignore user's time zone and force Date() use specific time zone
It seems to me that you can do something like this:
var date = new Date("6-25-2012 12:00:00 PM"); var offset = date.getTimezoneOffset(); // returns offset from GMT in minutes // to convert the minutes to milliseconds offset *= 60000; // the js primitive value is unix time in milliseconds so this retrieves the // unix time in milliseconds and adds our offset. // Now we can put this all back in a date object date = new Date(date.valueOf() + offset); // to get back your sting you can maybe now do something like this: var dateString = date.toLocaleString().replace(/\//g,'-').replace(',','');
Blame the JSON.Stringfy()... and do:
x = (your_date); x.setHours(x.getHours() - x.getTimezoneOffset() / 60);
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