RE: [xwiki-users] Date value compare (and update on date arithmetic)
Jérémi: You make it look easy, but it took me a good long bit of searching and trial-and-error investigation to figure out how to get a real Date object out of an XWiki object field. And you perform a little leger-de-main which I have not found explained anywhere: the expression $obj.XWikiObject.date.value is equivalent to $obj.XWikiObject.getDateValue("date"). Unfortunately, this is not suitable for use as an lvalue, but it makes a nice shorthand. Is this documented anywhere (other than in the source)? I noted the same thing when I found, in some sample code, a call to a (seemingly) nonexistent method $xwiki.getCalendar(). Happily, simply writing $xwiki.calendar in a document yielded an object identifier containing the classname com.xpn.xwiki.plugin.calendar.CalendarAPI, so it seems that XWiki was fiddling my call into $xwiki.get("calendar"), which is documented to return a plugin API, which before this had meant nothing to me (either that, or the plugin augmented com.xpn.xwiki.api.XWiki with a getCalendar() method, which is what I thought before I saw the above). Velocity, of course, turns any rvalue reference to $obj.foo into a call to $obj.getFoo() or $obj.getfoo(), and likewise any lvalue reference in a #set into a call to $obj.set[Ff]oo() with the RHS as its argument. But this trick is different, because at least in the first case it has to know the navigation of a particular XWiki-specific class hierarchy. Nice shorthand; would be nicer if it were explained somewhere... Okay, I'll do it... By the way, that $xwiki.calendar property finally got me to an answer to my date arithmetic problem, thanks to Java reflection. The task was in a project status reporting page, where I wanted to ignore records more than a week old. The problem was that I could find no way at all to do date arithmetic in a Velocity script, because the time value returned from java.util.Date.getTime() is a long integer, which (until the next release of Velocity, at least) can't be used in an arithmetic expression. I could have used the Date functions to format a date, manipulate the string version, and then parse it, but that would be far too difficult, inflexible, and error-prone even ignoring the fact that those methods were deprecated. It works like this, for those who are interested: First, $xwiki.calendar has a method getCalendar() which, in the version without arguments, returns a java.util.Calendar initialized with the current date. Because it inherits from java.lang.Object, it is Cloneable, so I clone()d it to get a copy that I could set back seven days, without disturbing the original object (I learned this the hard way: the returned object was a reference, and changes via the copied reference changed the original). Turning back the clock in a java.util.Calendar by seven days is quite simple in Java - formally speaking, it's java.util.Calendar.add(java.util.Calendar.DAY_OF_YEAR, -7). However, this isn't Java exactly; we can call the add() method easily enough, because we have a Calendar object, but that DAY_OF_YEAR symbolic constant isn't accessible that way, because apparently Velocity doesn't translate field references, only method calls. The final expression was $xwiki.calendar.calendar.class.getField("DAY_OF_YEAR").int #set($wcal = $xwiki.calendar.calendar.clone()) ## copy of java.util.Calendar with current time $wcal.add($wcal.class.getField("DAY_OF_YEAR").int, -7) ## set the calendar back one week. #set($weekago = $wcal.time) ## get the resulting date as a java.util.Date object After this, when I wanted to see whether date "donedate" from an object was more than a week old, I wrote something like this: #set($weekold = $obj.xWikiObject.donedate.value.before($weekago)) which worked just fine. Of course, since I also wanted to sort those records on other than the default field, I needed to do an $xwiki.search() call with a custom query, and SQL can easily do date arithmetic. That brings up another topic, because I was foolish enough to try it... brain[sic] -----Original Message----- From: jeremi joslin [mailto:[email protected]] Sent: Wednesday, March 22, 2006 8:25 AM To: [email protected] Subject: Re: [xwiki-users] Date value compare On 3/22/06, [email protected] <[email protected]> wrote:
Hello,
I've got several classes in which I use date attributes. Is there a way to list objects of such a class, but only those in which the value of the date attribute is before current date?
I do it a while ago using the before function: #if ($obj.XWikiObject.date.value.before($xwiki.getCurrentDate())) Jérémi -- Blog: http://www.jeremi.info LinkedIn: https://www.linkedin.com/profile?viewProfile=&key=1437724 Project Manager XWiki: http://www.xwiki.org skype: jeremi23 -- msn et gtalk : [email protected]
Yes, I understand. XWiki is not very well documented. Cody start a really good job on the documentation, but doesn't have time to continue it, maybe we didn't help him enought too. We will try to make an effort on this for the release 1.0. I hear that ludovic and jv will soon comment the API when they will find a day to do it. For comming back to your problem, like i said you offlist, if I remember, the better for a script like yours is using a groovy script. Velocity is great for easy things, but for more complicated like what you want groovy is very cool. With groovy, you can instanciate objects, like with velocity, access to the same API... Jérémi On 3/23/06, THOMAS, BRIAN M (SBCSI) <[email protected]> wrote:
Jérémi:
You make it look easy, but it took me a good long bit of searching and trial-and-error investigation to figure out how to get a real Date object out of an XWiki object field.
And you perform a little leger-de-main which I have not found explained anywhere: the expression $obj.XWikiObject.date.value is equivalent to $obj.XWikiObject.getDateValue("date"). Unfortunately, this is not suitable for use as an lvalue, but it makes a nice shorthand. Is this documented anywhere (other than in the source)?
I noted the same thing when I found, in some sample code, a call to a (seemingly) nonexistent method $xwiki.getCalendar(). Happily, simply writing $xwiki.calendar in a document yielded an object identifier containing the classname com.xpn.xwiki.plugin.calendar.CalendarAPI, so it seems that XWiki was fiddling my call into $xwiki.get("calendar"), which is documented to return a plugin API, which before this had meant nothing to me (either that, or the plugin augmented com.xpn.xwiki.api.XWiki with a getCalendar() method, which is what I thought before I saw the above).
Velocity, of course, turns any rvalue reference to $obj.foo into a call to $obj.getFoo() or $obj.getfoo(), and likewise any lvalue reference in a #set into a call to $obj.set[Ff]oo() with the RHS as its argument. But this trick is different, because at least in the first case it has to know the navigation of a particular XWiki-specific class hierarchy.
Nice shorthand; would be nicer if it were explained somewhere... Okay, I'll do it...
By the way, that $xwiki.calendar property finally got me to an answer to my date arithmetic problem, thanks to Java reflection.
The task was in a project status reporting page, where I wanted to ignore records more than a week old. The problem was that I could find no way at all to do date arithmetic in a Velocity script, because the time value returned from java.util.Date.getTime() is a long integer, which (until the next release of Velocity, at least) can't be used in an arithmetic expression. I could have used the Date functions to format a date, manipulate the string version, and then parse it, but that would be far too difficult, inflexible, and error-prone even ignoring the fact that those methods were deprecated. It works like this, for those who are interested:
First, $xwiki.calendar has a method getCalendar() which, in the version without arguments, returns a java.util.Calendar initialized with the current date. Because it inherits from java.lang.Object, it is Cloneable, so I clone()d it to get a copy that I could set back seven days, without disturbing the original object (I learned this the hard way: the returned object was a reference, and changes via the copied reference changed the original).
Turning back the clock in a java.util.Calendar by seven days is quite simple in Java - formally speaking, it's java.util.Calendar.add(java.util.Calendar.DAY_OF_YEAR, -7). However, this isn't Java exactly; we can call the add() method easily enough, because we have a Calendar object, but that DAY_OF_YEAR symbolic constant isn't accessible that way, because apparently Velocity doesn't translate field references, only method calls. The final expression was $xwiki.calendar.calendar.class.getField("DAY_OF_YEAR").int
#set($wcal = $xwiki.calendar.calendar.clone()) ## copy of java.util.Calendar with current time $wcal.add($wcal.class.getField("DAY_OF_YEAR").int, -7) ## set the calendar back one week. #set($weekago = $wcal.time) ## get the resulting date as a java.util.Date object
After this, when I wanted to see whether date "donedate" from an object was more than a week old, I wrote something like this:
#set($weekold = $obj.xWikiObject.donedate.value.before($weekago))
which worked just fine.
Of course, since I also wanted to sort those records on other than the default field, I needed to do an $xwiki.search() call with a custom query, and SQL can easily do date arithmetic.
That brings up another topic, because I was foolish enough to try it...
brain[sic]
-----Original Message----- From: jeremi joslin [mailto:[email protected]] Sent: Wednesday, March 22, 2006 8:25 AM To: [email protected] Subject: Re: [xwiki-users] Date value compare
On 3/22/06, [email protected] <[email protected]> wrote:
Hello,
I've got several classes in which I use date attributes. Is there a way to list objects of such a class, but only those in which the value of the date attribute is before current date?
I do it a while ago using the before function: #if ($obj.XWikiObject.date.value.before($xwiki.getCurrentDate()))
Jérémi -- Blog: http://www.jeremi.info LinkedIn: https://www.linkedin.com/profile?viewProfile=&key=1437724 Project Manager XWiki: http://www.xwiki.org skype: jeremi23 -- msn et gtalk : [email protected]
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-- Blog: http://www.jeremi.info LinkedIn: https://www.linkedin.com/profile?viewProfile=&key=1437724 Project Manager XWiki: http://www.xwiki.org skype: jeremi23 -- msn et gtalk : [email protected]
participants (2)
-
jeremi joslin -
THOMAS, BRIAN M (SBCSI)