问题
I am using the DateFormat function to convert dates to this format: yyyy-mm-dd. This is the original format of the date: dd-mm-yyyy. Below is a snippet of the code:
<cfset newdate = #DateFormat(Trim(mydate), "yyyy-mm-dd")# />
The problem is that I get different results for different dates. For example:
- If my original date is:
15-05-2013(dd-mm-yyyy) - The result is:
2013-05-15(yyyy-mm-dd)
However, if I change the input and:
- The original date is:
01-05-2013(dd-mm-yyyy) - The result is:
2013-01-05(yyyy-dd-mm)
Any help or guidance as to what is wrong would be highly appreciated.
回答1:
I disagree with the other answer. The real cause of the problem is that DateFormat is not designed to handle non-US date strings.
The standard CF date functions always use U.S. date parsing rules. That means when you pass in an ambiguous date string, like 01-05-2013, it is parsed according to U.S. English date conventions. In this case, month first ie "mm-dd-yyyy". So the result will always be January 5th, not May 1st.
In some cases you get lucky. With the string 15-05-2013, there is obviously no 15th month, so CF/java must swap the month and day automatically, rather than throwing an error. That is why it seems to handle some dd-mm-yyyy date strings correctly, but not others.
If you want to parse non-US date strings, you should use the LS (Locale Sensitive) date functions instead. However, according to the docs dashes ie "-" are not a standard date separator in most non-US locales: only Dutch and Portuguese (Standard). So you would either need to change the separator OR use one of those two locales when parsing the date:
lsDateFormat( myDate, "yyyy-mm-dd", "pt_PT")
Side note:
As an aside, DateFormat does expect a date object. However, like most functions in CF it is flexible enough to accept a date string as well. That allows you to use it as a lazy shortcut to convert from date string => date object => then back to (formatted) date string again. Using date objects is preferable (and you really should validate date strings as well) but that is another conversation altogether ...
回答2:
The problem is that DateFormat expects a date object, and returns a string.
You're passing it a string, not a date. What you want to do is firstly turn your string (of 01-05-2013 etc) into a date object.
To do this I'd recommend using either ParseDateTime or LSParseDateTime, and/or LSDateFormat.
e.g.
<cfset originalDateString = "01-05-2013">
<!--- turn that into a Date --->
<cfset dateObject = ParseDateTime(originalDateString)>
<cfset newdateString = DateFormat(dateObject, "yyyy-mm-dd")>
Alternatively, if you know your string is always in a dd-mm-yyyy format, you could parse the string yourself, e.g. treat it as a list delimited by hyphens.
<cfset dd = listFirst(originalDateString, "-")>
<cfset mm = listGetAt(originalDateString, 2, "-")>
<cfset yy = listLast(originalDateString, "-")>
来源：https://stackoverflow.com/questions/16557244/coldfusion-10-dateformat-issue