将日期字符串解析为某个时区(支持夏令时) [英] Parse a date string into a certain timezone (supporting daylight saving time)

问题描述

好的，过去几周我一直在努力工作，但遇到了一个小问题.我不认为我的头脑现在完全能够胜任这项任务:) 所以我需要一些提示/帮助！这可能很简单，但我的脑袋还没动.

用户将在 AEST 中输入日期和时间.还有一个应用程序设置默认"时区(因为它可能需要更改)，当前设置为澳大利亚东部标准时间"

所以我们在美国的服务器上有一个没有时区的用户字符串和一个定义的系统时区(所以本地不匹配，不能更改或使用)

现在我需要的是一种方式来表示使用时区 X 解析此用户输入的字符串"我不能只输入 +10 或 +11 作为偏移量，因为日期可能在夏令时之内或之外；是的，即使在同一时区，它也会在 +10 和 +11 之间改变！

当前 AEST 时间也可能在 DST 之内或之外，因此我不能只将 UTC 日期转换为当前 AEST 时间并获取zzz"字符串并将其附加，因为日期将相差一个小时在当前 DST 设置之外输入的任何内容.

现在代码实际上就是这样做的:

TimeZoneInfo ConvTo = TimeZoneInfo.FindSystemTimeZoneById(ConfigurationManager.AppSettings["DefaultTimeZone"]);DateTimeOffset getDate = TimeZoneInfo.ConvertTime(DateTimeOffset.UtcNow, ConvTo);字符串 TimeZoneId = " " + getDate.ToString("zzz");DateTimeOffset cvStartDate = DateTimeOffset.MinValue;DateTimeOffset.TryParse(StartDate + TimeZoneId, out cvStartDate);

然后我通过检查日期是否仍然 == DateTimeOffset.MinValue 或将其转换为 UTC 并添加到数据库来检查日期是否无效，显示时它将被转换回 AEST.然而，有些日期相差一个小时，而其他日期则完美(如预期):)

解决这个问题最优雅的方法是什么?

为了帮助解释问题，我编写了一些测试代码作为 Windows 测试应用程序:

//用户输入的日期字符串 EnteredDate = "2011/01/01 10:00:00 AM";//获取我们要使用的时区TimeZoneInfo myTimeZone = TimeZoneInfo.FindSystemTimeZoneById("澳大利亚东部标准时间");//查找选中时区的时区字符串解析用户字符串//这是不正确的部分，我需要帮助.DateTimeOffset getDate = TimeZoneInfo.ConvertTime(DateTimeOffset.UtcNow, myTimeZone);字符串 TimeZoneId = " " + getDate.ToString("zzz");//将字符串解析为日期对象DateTimeOffset cvEnteredDate = DateTimeOffset.MinValue;DateTimeOffset.TryParse(EnteredDate + TimeZoneId, out cvEnteredDate);//展示textBox1.Text += "已解析:" + cvEnteredDate.ToString("yyyy/MM/dd HH:mm:ss zzz") + Environment.NewLine;//转换为UTC并显示cvEnteredDate = cvEnteredDate.ToUniversalTime();textBox1.Text += "UTC:" + cvEnteredDate.ToString("yyyy/MM/dd HH:mm:ss zzz") + Environment.NewLine;//转换回 AEST 并显示cvEnteredDate = TimeZoneInfo.ConvertTime(cvEnteredDate, myTimeZone);textBox1.Text += "改回:" + cvEnteredDate.ToString("yyyy/MM/dd HH:mm:ss zzz") + Environment.NewLine;

这是什么输出?

<上一页>解析:2011/01/01 10:00:00 +10:00UTC: 2011/01/01 00:00:00 +00:00改回:2011/01/01 11:00:00 +11:00

请注意小时减一并且偏移量不同.此外，如果我们只是将输入的日期更改为:

string EnteredDate = "2011/04/20 10:00:00 AM";

我们得到:

<上一页>解析:2011/04/20 10:00:00 +10:00UTC: 2011/04/20 00:00:00 +00:00改回:2011/04/20 10:00:00 +10:00

这很好，很好，使用相同的代码只是输入不同的日期.

发生这种情况是因为当前 DST 设置和输入日期的 DST 设置不同，这就是我想要的解决方案:)

把它想象成鸡和蛋的问题.在解析输入的字符串之前，我需要正确的时区数据，只有在我解析完字符串后才能获得(因此将是一个精心设计的解决方案)

或者我需要 .NET 使用 myTimeZone 对象解析字符串，以便它知道将其设置为自身，但我看不到任何执行此操作的函数，它们 all 已经解析并设置 datetime 或 datetimeoffset 对象

所以我正在寻找其他人可能已经完成的优雅解决方案?我肯定不会是唯一注意到这一点的人吗?

好的，我已经制作了一个工作"函数来解决我认为的问题，这是一个示例(将文本框添加到 c# windows 应用程序并使用下面的代码来测试自己):

private void Form1_Load(object sender, EventArgs e){TimeZoneInfo myTimeZone = TimeZoneInfo.FindSystemTimeZoneById("澳大利亚东部标准时间");DateTimeOffset get1Date = ReadStringWithTimeZone("2011/01/01 10:00:00 AM", myTimeZone);textBox1.Text += "Read1:" + get1Date.ToString("yyyy/MM/dd HH:mm:ss zzz") + Environment.NewLine;get1Date = get1Date.ToUniversalTime();textBox1.Text += "Read1 - UTC:" + get1Date.ToString("yyyy/MM/dd HH:mm:ss zzz") + Environment.NewLine;get1Date = TimeZoneInfo.ConvertTime(get1Date, myTimeZone);textBox1.Text += "改回:" + get1Date.ToString("yyyy/MM/dd HH:mm:ss zzz") + Environment.NewLine + Environment.NewLine;DateTimeOffset get2Date = ReadStringWithTimeZone("2011/04/20 10:00:00 AM", myTimeZone);textBox1.Text += "Read2:" + get2Date.ToString("yyyy/MM/dd HH:mm:ss zzz") + Environment.NewLine;get2Date = get2Date.ToUniversalTime();textBox1.Text += "Read2 - UTC:" + get2Date.ToString("yyyy/MM/dd HH:mm:ss zzz") + Environment.NewLine;get2Date = TimeZoneInfo.ConvertTime(get2Date, myTimeZone);textBox1.Text += "改回:" + get2Date.ToString("yyyy/MM/dd HH:mm:ss zzz") + Environment.NewLine + Environment.NewLine;}public DateTimeOffset ReadStringWithTimeZone(string EnteredDate, TimeZoneInfo tzi){DateTimeOffset cvUTCToTZI = TimeZoneInfo.ConvertTime(DateTimeOffset.UtcNow, tzi);DateTimeOffset cvParsedDate = DateTimeOffset.MinValue;DateTimeOffset.TryParse(EnteredDate + " " + cvUTCToTZI.ToString("zzz"), out cvParsedDate);如果(tzi.SupportsDaylightSavingTime){TimeSpan getDiff = tzi.GetUtcOffset(cvParsedDate);string MakeFinalOffset = (getDiff.Hours < 0 ? "-" : "+") + (getDiff.Hours > 9 ? "" : "0") + getDiff.Hours + ":" + (getDiff.Minutes >9 ? "" : "0") + getDiff.Minutes;textBox1.Text += "差异:" + MakeFinalOffset + Environment.NewLine;DateTimeOffset.TryParse(EnteredDate + " " + MakeFinalOffset, out cvParsedDate);返回 cvParsedDate;}别的{返回 cvParsedDate;}}

还有输出:

<上一页>差异:+11:00阅读1:2011/01/01 10:00:00 +11:00读取 1 - UTC:2010/12/31 23:00:00 +00:00改回:2011/01/01 10:00:00 +11:00差异:+10:00阅读2:2011/04/20 10:00:00 +10:00读取 2 - UTC:2011/04/20 00:00:00 +00:00改回:2011/04/20 10:00:00 +10:00

唯一的问题是，如果用户输入的日期在 DST 小时的变化上是正确的，它仍然可能是一个小时的时间，因为它只是读取当前的偏移量并使用它，然后检查它是否应该是夏令时与否，如果它在那里，它会读取不正确.但是，它比我现在拥有的要好几英里.

谁能帮我清理这个功能?这是我需要的最佳路线吗?想法?

解决方案

这是一个预定义格式的简单解决方案，这也可以是动态的.我个人用它来与 javascript 交谈:

public DateTimeOffset ParseDateExactForTimeZone(string dateTime, TimeZoneInfo timezone){var parsedDateLocal = DateTimeOffset.ParseExact(dateTime, "yyyy-MM-dd HH:mm:ss", CultureInfo.InvariantCulture);var tzOffset = timezone.GetUtcOffset(parsedDateLocal.DateTime);var parsedDateTimeZone = new DateTimeOffset(parsedDateLocal.DateTime, tzOffset);返回解析日期时间区；}

Ok i've been working very hard the last few weeks and i've come across a small problem. I don't think my mind is quite up to the task right now :) so i need some tips/help! it's likely very simple but my head isn't clicking yet.

Users will enter a date and time in AEST. There is also a application set "default" timezone (as it might need to change), currently its set to "AUS Eastern Standard Time"

So we have a user string with no time zone and a defined system time zone on a server in the USA (So local doesn't match and it can't be changed or used)

Now what i need is a way to say "parse this user entered string using the timezone X" i can't just enter +10 or +11 as the offset as the dates could be in or out of daylight savings; which yes does change it between +10 and +11 even for the same timezone!

The current AEST time might also be in or out of DST so i can't just convert a UTC date to the current AEST time and get the "zzz" string and attach it either as dates will be off by an hour for anything entered out of the current DST setting.

For now the code actually does just that:

TimeZoneInfo ConvTo = TimeZoneInfo.FindSystemTimeZoneById(ConfigurationManager.AppSettings["DefaultTimeZone"]);
DateTimeOffset getDate = TimeZoneInfo.ConvertTime(DateTimeOffset.UtcNow, ConvTo);
string TimeZoneId = " " + getDate.ToString("zzz");
DateTimeOffset cvStartDate = DateTimeOffset.MinValue; DateTimeOffset.TryParse(StartDate + TimeZoneId, out cvStartDate);

Then i check if the date isn't valid by checking if it still == DateTimeOffset.MinValue or convert it to UTC and add to the database, it will the be converted back to AEST when displayed. However some dates are off by an hour and others are perfect (as expected) :)

What is the most elegant way to solve this?

EDIT:

To help explain the problem, i wrote some test code as a windows test application:

// User entered date
string EnteredDate = "2011/01/01 10:00:00 AM";

// Get the timezone we want to use
TimeZoneInfo myTimeZone = TimeZoneInfo.FindSystemTimeZoneById("AUS Eastern Standard Time");

// Find the timezone string of the selected timezone to parse the user string
// This is the part that is incorrect and what i need help with.
DateTimeOffset getDate = TimeZoneInfo.ConvertTime(DateTimeOffset.UtcNow, myTimeZone);
string TimeZoneId = " " + getDate.ToString("zzz");

// Parse the string into the date object
DateTimeOffset cvEnteredDate = DateTimeOffset.MinValue; DateTimeOffset.TryParse(EnteredDate + TimeZoneId, out cvEnteredDate);

// Display
textBox1.Text += "Parsed: " + cvEnteredDate.ToString("yyyy/MM/dd HH:mm:ss zzz") + Environment.NewLine;

// Convert to UTC and display
cvEnteredDate = cvEnteredDate.ToUniversalTime();
textBox1.Text += "UTC: " + cvEnteredDate.ToString("yyyy/MM/dd HH:mm:ss zzz") + Environment.NewLine;

// Convert back to AEST and display
cvEnteredDate = TimeZoneInfo.ConvertTime(cvEnteredDate, myTimeZone);
textBox1.Text += "Changed Back: " + cvEnteredDate.ToString("yyyy/MM/dd HH:mm:ss zzz") + Environment.NewLine;

Whats the output of this?

Parsed: 2011/01/01 10:00:00 +10:00
UTC: 2011/01/01 00:00:00 +00:00
Changed Back: 2011/01/01 11:00:00 +11:00

Please note the hour is off by one and the offset is different. Additionally, what if we JUST change the date entered to:

string EnteredDate = "2011/04/20 10:00:00 AM";

we get:

Parsed: 2011/04/20 10:00:00 +10:00
UTC: 2011/04/20 00:00:00 +00:00
Changed Back: 2011/04/20 10:00:00 +10:00

Which is perfectly good and fine, using the same code just a different entered date.

This happens because the current DST setting and the DST setting of the entered date are different, this is what i want a solution for :)

Think of it like the chicken and egg problem. I need the correct timezone data for the entered string before i parse it which i can only get after i've parsed the string (so will be an elaborate solution)

Or i need .NET to parse the string using the myTimeZone object so it knows what to set it to itself, but i can't see any functions that do this, they all take a already parsed and set datetime or datetimeoffset object

So i'm looking for elegant solutions others might have done? I certainly can't be the only one who has noticed this?

EDIT2:

Ok i've made a 'working' function that solves the problem i think, here is an example (add a textbox to a c# windows app and use the code below to test yourself):

private void Form1_Load(object sender, EventArgs e)
{
    TimeZoneInfo myTimeZone = TimeZoneInfo.FindSystemTimeZoneById("AUS Eastern Standard Time");

    DateTimeOffset get1Date = ReadStringWithTimeZone("2011/01/01 10:00:00 AM", myTimeZone);
    textBox1.Text += "Read1: " + get1Date.ToString("yyyy/MM/dd HH:mm:ss zzz") + Environment.NewLine;
    get1Date = get1Date.ToUniversalTime();
    textBox1.Text += "Read1 - UTC: " + get1Date.ToString("yyyy/MM/dd HH:mm:ss zzz") + Environment.NewLine;
    get1Date = TimeZoneInfo.ConvertTime(get1Date, myTimeZone);
    textBox1.Text += "Changed Back: " + get1Date.ToString("yyyy/MM/dd HH:mm:ss zzz") + Environment.NewLine + Environment.NewLine;

    DateTimeOffset get2Date = ReadStringWithTimeZone("2011/04/20 10:00:00 AM", myTimeZone);
    textBox1.Text += "Read2: " + get2Date.ToString("yyyy/MM/dd HH:mm:ss zzz") + Environment.NewLine;
    get2Date = get2Date.ToUniversalTime();
    textBox1.Text += "Read2 - UTC: " + get2Date.ToString("yyyy/MM/dd HH:mm:ss zzz") + Environment.NewLine;
    get2Date = TimeZoneInfo.ConvertTime(get2Date, myTimeZone);
    textBox1.Text += "Changed Back: " + get2Date.ToString("yyyy/MM/dd HH:mm:ss zzz") + Environment.NewLine + Environment.NewLine;
}

public DateTimeOffset ReadStringWithTimeZone(string EnteredDate, TimeZoneInfo tzi)
{
    DateTimeOffset cvUTCToTZI = TimeZoneInfo.ConvertTime(DateTimeOffset.UtcNow, tzi);
    DateTimeOffset cvParsedDate = DateTimeOffset.MinValue; DateTimeOffset.TryParse(EnteredDate + " " + cvUTCToTZI.ToString("zzz"), out cvParsedDate);
    if (tzi.SupportsDaylightSavingTime)
    {
        TimeSpan getDiff = tzi.GetUtcOffset(cvParsedDate);
        string MakeFinalOffset = (getDiff.Hours < 0 ? "-" : "+") + (getDiff.Hours > 9 ? "" : "0") + getDiff.Hours + ":" + (getDiff.Minutes > 9 ? "" : "0") + getDiff.Minutes;
        textBox1.Text += "Diff: " + MakeFinalOffset + Environment.NewLine;
        DateTimeOffset.TryParse(EnteredDate + " " + MakeFinalOffset, out cvParsedDate);
        return cvParsedDate;
    }
    else
    {
        return cvParsedDate;
    }
}

And the output:

Diff: +11:00
Read1: 2011/01/01 10:00:00 +11:00
Read1 - UTC: 2010/12/31 23:00:00 +00:00
Changed Back: 2011/01/01 10:00:00 +11:00

Diff: +10:00
Read2: 2011/04/20 10:00:00 +10:00
Read2 - UTC: 2011/04/20 00:00:00 +00:00
Changed Back: 2011/04/20 10:00:00 +10:00

Only thing is there might be a problem if the user entered date is right on the change over hour of DST it still might be an hour off as it's just reading the current offset and using that, then checking if its supposed to be daylight savings or not, and if its out there it would read incorrectly. However it's miles better than what i have now.

Can anyone maybe help me with cleaning up this function? Is this the best route go down for what i need? ideas?

解决方案

Heres a simple solution for a predefined format, this can be dynamic as well. I personally use this for talking with javascript:

public DateTimeOffset ParseDateExactForTimeZone(string dateTime, TimeZoneInfo timezone)
{
    var parsedDateLocal = DateTimeOffset.ParseExact(dateTime, "yyyy-MM-dd HH:mm:ss", CultureInfo.InvariantCulture);
    var tzOffset = timezone.GetUtcOffset(parsedDateLocal.DateTime);
    var parsedDateTimeZone = new DateTimeOffset(parsedDateLocal.DateTime, tzOffset);
    return parsedDateTimeZone;
}

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