Re: how does cayenne handle java.util.date values ?
Yeah, daylight saving time is tricky... Though the Date object still
stores information about the timezone. I am surprised the driver
doesn't account for it. Here is a few options that you have:
1. [the simplest] If you can redesign your database, I'd suggest
storing dates as long numbers.
2. Normalize dates as pseudo-UTC (i.e. subtracting an absolute
difference with UTC, that should take into account the daylight
saving time):
Calendar cal1 = new GregorianCalendar();
cal1.setTime(date1);
int offsetMinutes = -(cal1.get(Calendar.ZONE_OFFSET) + cal1.get
(Calendar.DST_OFFSET)) / (60 * 1000);
But again, I am surprised that driver doesn't do that for you - may
require more research with your DB...
Andrus
On Dec 8, 2006, at 5:58 PM, Lothar Krenzien wrote:
Hi,
because I didn't solved the problems of my previous posts I've
tried to create another demo. Basicly I have the following
situation. I get an xml file (via a servlet) which contains a comma-
separated list of values (for example energy values) and a start
date. So the file could looks like :
startDate28.10.2006 22:14:28/startDate
valueList0.2 , 0.5 , 0.7, 0.9/valueList
The first entry should be aligned to the last quarter before (!)
the startDate. And then I have to iterate over the value list and
align each value to the next quarter. The result should looks like :
28.10.2006 22:00 = 0.2
28.10.2006 22:15 = 0.5
28.10.2006 22:30 = 0.7
28.10.2006 22:45 = 0.9
Even if the startDate has always the format dd.MM. hh:mm it
could represents a different timezone. Let's say Asia/Seoul.
timezone = TimeZone.getTimeZone(Asia/Seoul);
dateFormat = new SimpleDateFormat(dd.MM. HH:mm:ss);
dateFormat.setTimeZone(timezone);
parsedDate = dateFormat.parse(startDate);
My problem now is, when I try to create a cayenne Tbl* object and
set the date value in it - the following value is stored in the
database Sat Oct 28 15:18:48 CEST 2006. But I would like to have
Sat Oct 28 22:18:48 CEST 2006. I think it's because
java.util.Date just stores the time in UTC and converts it
transparently to the default timezone.
Of course I can get a workaround for it. But the major problem for
me is the break in time during the change from summer- to
wintertime (the clock is turned back by 1h). In germay the clock
changes from 3:00 a.m. to 2:00 a.m. That courses that when I
proceed the value for 2:45 a.m the next value will be aligned to
2:00 a.m again. But in Korea there is no summer- or wintertime so
the value should be aligned to 3:00 a.m..
Generally that's not a problem because the timezone has a method
inDaylightTime() so that I know when the change was happen and can
skipp the unneeded values.
But as I just said, in Korea there is no daylighttime and thus no
need to skipp the values. But Java converts the (korean) date value
into a date value for the default timezone (germany here) and so I
have the values between 2:00 a.m and 3.00 a.m. twice. And that's
not allowed by the database.
When I convert the date back into a string using
dateFormat = new SimpleDateFormat(-MM-
dd HH:mm:ss.SSS, );
dateFormat.setTimeZone(timezone);
formattedDate = dateFormat.format(valueDate);
I get the correct date string back.
For me it looks like that cayenne (or maybe the jdbc driver) should
consider the timezone for a date.
I've provided two samples to illustrate what I mean. The first
small sample shows how cayenne stores date values. The second
sample shows the exception during the change in daylight time.
It would be nice if someone could try it out and could give a
comment on it.
Thanks, Lothar
the database tables
--
-
/*
CREATE TABLE [dbo].[tblEfficiencyBlock] (
[efficiencyBlockId] [int] IDENTITY (1, 1) NOT NULL ,
[serialNumber] [varchar] (50) COLLATE Latin1_General_CI_AS NULL
) ON [PRIMARY]
GO
CREATE TABLE [dbo].[tblEffBlockData] (
[effBlockDataId] [int] IDENTITY (1, 1) NOT NULL ,
[efficiencyBlockId] [int] NOT NULL ,
[dataDate] [datetime] NOT NULL ,
[energyValue] [float] NOT NULL
) ON [PRIMARY]
GO
CREATE UNIQUE
INDEX [IX_tblEffblockdata_1] ON [dbo].[tblEffBlockData]
([efficiencyBlockId], [dataDate])
WITH
DROP_EXISTING
ON [PRIMARY]
*/
/*
insert into tblEfficiencyBlock
(serialNumber)
values
('123456')
*/
-- the application code
void doTest{
energyValues = values.split(,);
valueDate = adjustDataDate(timezone, parsedDate);
for (String energyValue : energyValues) {
if (timezone.inDaylightTime(valueDate)) {
// skip some values
}
Re: how does cayenne handle java.util.date values ?
On Dec 5, 2006, at 14:26 , Lothar Krenzien wrote: I've provided a simple demo class to show what I mean. I used Java 5, cayenne 2.1 and jtds with MS SQL Server 2000. Looks like the attachment are striped by the mail-list software. Could you copy/paste the code into the mail instead of attaching the java file? - Tore.
Re: how does cayenne handle java.util.date values ?
Attachments are stripped from the messages sent to the list, so I can't check your example. So let me ask you this - are you using Cayenne XMLEncoder/XMLDecoder? It won't handle the dates properly ... the rest of Cayenne will. If this doesn't help, could you please post a relevant code example inline (not as an attachment). Andrus On Dec 5, 2006, at 3:26 PM, Lothar Krenzien wrote: Hi there, I posted this yesterday again. But have just seen that I forgott the subject. Sorry for that What I would like to know is how does cayenne handle java.util.date values ? My problem is, that I have to import xml files with datetime values in it of different timezones. For example the file contains the following tag: date=30.11.2006 22:14:28. In my case it should represents a datetime value of german format (dd.MM. hh.mm.ss) BUT in local korean time. Korean time has an offset of +9h to GMT. So in GMT the time part is 13:14:28 and in german time (GMT +1h) it's 14:14:28. For some historical reasons I have to persistent the local datetime value (28.10.2006 22:14:28), but of course as date object instead of a string value. When I now try to convert the string value into a date-object using standard java methods I will get an object which reflects GMT time. But when I try to print it out on a console it will be converted to local date (thus german date). And that date will be saved by cayenne in the database. So for me it looks like that cayenne tries to call toString() on the date object and will get a recalculated date instead of the original date. If it's true I think it would be better to use a SimpleDateFormatter instance because than the you will get a correct datetime string. I've provided a simple demo class to show what I mean. I used Java 5, cayenne 2.1 and jtds with MS SQL Server 2000. Thanks Lothar
Re: how does cayenne handle java.util.date values ?
-Ursprüngliche Nachricht-
Von: cayenne-user@incubator.apache.org
Gesendet: 05.12.06 14:33:50
An: cayenne-user@incubator.apache.org
Betreff: Re: how does cayenne handle java.util.date values ?
On Dec 5, 2006, at 14:26 , Lothar Krenzien wrote:
I've provided a simple demo class to show what I mean. I used Java
5, cayenne 2.1 and jtds with MS SQL Server 2000.
Looks like the attachment are striped by the mail-list software.
Could you copy/paste the code into the mail instead of attaching the
java file?
- Tore.
Ok here's the sample :
--
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.TimeZone;
public class CayenneDateTest {
public static void main(String[] args) {
try {
System.out.println(litte java date parsing + formating
sample);
doTest();
}
catch (Exception e) {
e.printStackTrace();
}
}
private static void doTest() throws Exception {
// the string value from the xml file
String dateValue = 28.10.2006 22:14:28;
TimeZone timeZone = TimeZone.getTimeZone(Asia/Seoul);
SimpleDateFormat dateFormat = new SimpleDateFormat(dd.MM.
HH:mm:ss);
dateFormat.setTimeZone(timeZone);
Date parsedDate = dateFormat.parse(dateValue);
System.out.println(parsedDate: + parsedDate); // this will be
stored by cayenne
dateFormat = new SimpleDateFormat(dd.MM. HH:mm:ss );
dateFormat.setTimeZone(timeZone);
String formattedDate = dateFormat.format(parsedDate);
System.out.println(formattedDate: + formattedDate);
dateFormat = new SimpleDateFormat(-MM-dd HH:mm:ss.SSS);
dateFormat.setTimeZone(timeZone);
formattedDate = dateFormat.format(parsedDate);
System.out.println(formattedDate: + formattedDate); // this
is what I like to be stored by cayenne
}
private static void doImport() {
// this is a pseudo example how the real application does the
db import
/*
String dataDate = 28.10.2006 22:14:28 ;
TimeZone timeZone = TimeZone.getTimeZone(Asia/Seoul);
SimpleDateFormat dateFormat = new SimpleDateFormat(dd.MM.
HH:mm:ss);
dateFormat.setTimeZone(timeZone);
Date parsedDate = dateFormat.parse(dataDate);
TblImportEffBlockData importData =
(TblImportEffBlockData)context.createAndRegisterNewObject(TblImportEffBlockData.class);
importData.setDataDate(parsedDate);
context.commitChanges();*/
/*
-- cayenne log output
INSERT INTO dbo.tblImportEffBlockData
(dataDate)
bind: '2006-10-28 15:14:28.0'
*/
/*
-- db table definition
CREATE TABLE [dbo].[tblImportEffBlockData] (
[importEffBlockDataId] [int] IDENTITY (1, 1) NOT NULL ,
[dataDate] [datetime] NOT NULL
) ON [PRIMARY]
GO
*/
}
}
--
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