Develop Reference

How to use Compare Validator for dates if the date is split in several fields?

I am finishing a form in C#, and I would like to validate the data entry. I have seen numerous posts about validating with "CompareValidator". That's fine and clear.
I just would like to ask about a twist: I have the date in one field, result of using the AjaxControlToolkit Calendar Extender. You can retrieve it as:
DateField.Text;
Then I have the hour in another field of the form, using MKB Time Select package from NuGet.
TimeSelector1.Hour + ":" + TimeSelector1.Minute
is the value I want to use.
So the user has been filling the form, and picked a date from the date field, and an hour from the time selector. I want to check if the date and time that the user selects in these fields, is at least 24 hours greater than the current time, so it means the validator needs to use these two different fields to grab the initial data.
I am a bit confused about how would I get started about that.
Basically, the validator should show the warning if
DateField.Text + " " + TimeSelector1.Hour + ":" + TimeSelector1.Minute
is greater than
DateTime.Now.AddHours(24)
But I don't see clear how to tell the validator to validate this sort of statements, rather than the plain content on the fields.

With the information provided, you should be able to parse your values into a DateTime object.
string dateString = String.Format("{0} {1}:{2}:00", DateField.Text, TimeSelector1.Hour, TimeSelector1.Minute);
DateTime selectedDateTime = new DateTime();
if (DateTime.TryParse(dateString, out selectedDateTime))
{
if (selectedDateTime > DateTime.Now.AddHours(24))
{
// code
}
}

At first you should parse your date and time strings into DateTime object then compare it with DateTime.Now.AddHours(24)
var inputDate = "20150606 10:12";
DateTime date;
if (!DateTime.TryParseExact(inputDate, "yyyyMMdd HH:mm" , CultureInfo.InvariantCulture, DateTimeStyles.None, out date))
{
//datetime has invalid format
}
else
{
if(date > DateTime.Now.AddHours(24))
{
//show warning
}
}

Omitting date from label text, only showing time

The following code displays the label as Planning horizon: 20/11/2014 08:00:00 to 20/11/2014 09:00:00, how do I get it to display it as Planning horizon: 08:00:00 to 09:00:00.
DateTime startTime = DateTime.Parse("08:00:00");
DateTime endTime = DateTime.Parse("09:00:00");
label1.Text = "Planning horizon: " + startTime + " to " + endTime;

Use .ToLongTimeString() or .ToShortTimeString() on your DateTimes.
DateTime x = DateTime.Now;
Console.WriteLine(x.ToLongTimeString());
Console.WriteLine(x.ToShortTimeString());
Will Generate:
9:30:20 AM
9:30 AM
For your specific output you may want to customize the output string, so instead do this:
startTime.ToString("HH:mm:ss")
Which outputs (note the HH outputs in a 24 hour clock):
09:30:14
See this MSDN page for more info on formatting time strings.

Just format your DateTime's with .ToString() method like;
label1.Text = "Planning horizon: " + startTime.ToString("HH:mm:ss") + " to "
+ endTime.ToString("HH:mm:ss");
Long Answer
Since you using string + DateTime concatenation, this process will call string + object overload and uses .ToString() method for the second parameter.
From DateTime.ToString() method;
The value of the current DateTime object is formatted using the
general date and time format specifier ('G').
This method uses formatting information derived from the current
culture. In particular, it combines the custom format strings returned
by the ShortDatePattern and LongTimePattern properties of the
DateTimeFormatInfo object returned by the
CurrentCulture.DateTimeFormat property
And looks like your CurrentCulture's ShortDatePattern and LongTimePattern is dd/MM/yyyy and HH:mm:ss. That's why you get string result based these concated formats.

Use the TimeOfDay function. See the link below for formatting options.
http://msdn.microsoft.com/en-us/library/system.datetime.timeofday%28v=vs.110%29.aspx

DateTime parsing error while parsing dd/MM/yyyy format. String was not recognized as valid datetime

I create a string using values from certain page elements in my web user control as below
string bookingdate = ddlDate.SelectedItem.Text
+ "/" + ddlMonth.SelectedValue + "/"
+ ddlMonth.SelectedItem.Text.Substring(4, 2);
and getting "String was not recognized as a valid DateTime." error on the following line
cmd.Parameters.Add(new SqlParameter("#ArrivalDate", SqlDbType.DateTime)).Value =
DateTime.ParseExact(bookingdate, "dd/MM/yyyy", CultureInfo.InvariantCulture);
How can I alter the value of this string "bookingdate" to troubleshoot the problem.

So ddlMonth contains items in this format (you posted the link to your page):
<option value="08">Aug 14</option>
Now you're trying to extract the month and year part from it:
ddlMonth.SelectedValue + "/" + ddlMonth.SelectedItem.Text.Substring(4, 2)
Your format string is this: dd/MM/yyyy
Do you already see the problem? The format string expects four digits for the year.
Instead use this format string: dd/MM/yy
DateTime.ParseExact(bookingdate, "dd/MM/yy", CultureInfo.InvariantCulture);

As I can understand you need Indian Date Format that is dd/mm/yyyy. So in your code, pass parameter as string and in sql handle it using Convert(date,Convert(datetime,#ArrivalDate,103)). Use date as your datatype if you need only date and is on Sql 2008 or above otherwise
Convert(datetime,#ArrivalDate,103) and leave your datatype as datetime
In cs:
cmd.Parameters.AddWithValue("#ArrivalDate", bookingdate);

DateTime.Parse throwing format exception

I retrieve date and time strings from xml by parsing XElement.
The date and time values are retrieved by
file.Element("Date").Value and file.Element("Time").Value respectively.
After I retrieve the Date value I parse it to a DateTime variable
DateTime dt,ts;
dt = file.Element("Date").Value; // the value is say 12/29/2012
and then this dt value is set to a datepicker value on the xaml UI
datepicker.Value = dt;
I also have a timepicker whose value have to be set by the Time value retrieved from xml.
To set the timepicker value I do the following.
declare 3 strings, say:
string a = file.Element("Time").Value; // the value is say 9:55 AM
string b = file.Element("Time").Value.Substring(0, 5) + ":00"; // eg 9:55:00
string c = file.Element("Time").Value.Substring(5); // the value is ' AM'
I then concatenate the Date Value and string 'b' and 'c'
string total = file.Element("Date").Value + " " + b + c;
the value of total is now '12/29/2012 9:55:00 AM'
I then try to Parse this total string to a DateTime, but it throws a formatexception
DateTime.Parse(total, CultureInfo.InvariantCulture);
Any help appreciated...

Try DateTime.ParseExact
var dateStr = "12/29/2012 09:55:00 AM";
DateTime date = DateTime.ParseExact(dateStr,"MM/dd/yyyy hh:mm:ss tt", System.Globalization.CultureInfo.InvariantCulture);
Demo here.
Read C# DateTime Format for format string detail.
Note that i have added extra 0 to hour part. It must be 2 digits otherwise format exception will occur.

Try using: DateTime.ParseExact
string total = '12/29/2012 9:55:00 AM';
string format = "MM/dd/yyyy H:mm:ss tt";
DateTime dateTime = DateTime.ParseExact(dateString, format,
CultureInfo.InvariantCulture);

I have got the solution for this.
When trying to save the datepicker in XML format, I was saving the value of timepicker as XMLElement as ValueString, hence when converted to string always throwed error.
So I saved it in XML format as Value.ToString().
Now it can convert correctly from String to Date or Time equivalents.

How to validate if a "date and time" string only has a time?

I have a single string variable that stores what could be a full date or a partial date:
1) Full Date: 12/12/2010 12:33 AM
2) Partial Date: 12:33 AM (no date field only time)
I'm trying to figure out what would be the best approach to parse the string to figure out if the string is missing the date string or not. The reason is, in my code if the date is missing I will append a default date to the string (such as 1/1/1900). Keep in mind that the time could be in various formats.
Update - My particular answer to this problem.
As all the "posts" have stated, there are multiple answers to this problem, this is ultimately what I used and hope it can help others*:
public DateTime ProcessDateAndTime(string dateString)
{
string dateAndTimeString = dateString;
string[] timeFormats = new string[]
{
"hh:mm tt", "hh:mm:ss tt",
"h:mm tt", "h:mm:ss tt",
"HH:mm:ss", "HH:mm", "H:mm"
};
// check to see if the date string has a time only
DateTime dateTimeTemp;
if (DateTime.TryParseExact(dateString, timeFormats,
CultureInfo.InvariantCulture.DateTimeFormat, DateTimeStyles.None, out dateTimeTemp))
{
// setting date to 01/01/1900
dateAndTimeString = new DateTime(1900, 1, 1).ToShortDateString() + " " + dateString;
}
return DateTime.Parse(dateAndTimeString);
}
*Note: This method is based on the assumption that there are only a specific amount of time formats used in your application, and that it is guaranteed that a properly formatted date and time, or time only string passed in (pre-validation for removal of garbage text).

Use
Convert.ToDateTime(string value, IFormatProviderProvider provider)
Since the string comes in different flavors, provide different format providers as needed.
The order could be:
DateOnly
Time Only
DateTime
The convert will throw an format exception if it fails. If you prefer not to have exceptions, use Datetime.TryParse instead as that returns a boolean.
Depending on how the string is represented you could have more than 3 format providers.

You can try to validate string with a RegEx,
BTW, good regexes for DateTime validation can be found here

Here's one way to do this without knowing all possible time formats:
CultureInfo provider = CultureInfo.CurrentCulture;
DateTime time;
DateTime datetime;
bool isTime = DateTime.TryParse(dateString, provider, DateTimeStyles.NoCurrentDateDefault, out time)
&& time.Date == DateTime.MinValue.Date
&& DateTime.TryParse(dateString, provider, DateTimeStyles.None, out datetime)
&& datetime.Date != DateTime.MinValue.Date);
If the string only has a time then the first TryParse will set the date part to 1/1/0001 or DateTime.MinValue.Date and the second TryParse will set the date part to the current date. This will work unless it is run by Doctor Who after travelling back in time to 1/1/0001.

You can use DateTime.TryParseExact.

This might not be the best but it answers your question:
string dateString = "9:53AM";
if (!dateString.Contains('/')))
{
dateString = DateTime.Now.ToShortDateString() + " " + dateString;
}

Looking at the length of the string will be straight-forward and will support multiple formats. A string with a date and time will most certainly be longer than a string with just a time. However, if your input may have times with high precision (12:30:30:50:20 vs 12/11/11 12:30) and low precision this won't work.
This solution is ideal if you don't need to know the value in the string immediately, and only want to add the default date.
If you support times to the second, for instance, a time will have 8 or less characters and a date-time will have 9 or more.

Given that the time can be in various formats (12/24?) it would be best to user several patterns, in some pre-defined order, trying to parse with each and resolving when the first succeeds.

You can also try
DateTime aTime;
if (DateTime.TryParse(dateString, CultureInfo.InvariantCulture.DateTimeFormat, DateTimeStyles.NoCurrentDateDefault, out aTime))
{
//if the there is no date part in the dateString, date will
// default to Gregorian 1/1/0001
}