dhis2-devs team mailing list archive

[Saptarshi Purkayastha <sunbiz@xxxxxxxxx>]

Not joda-time exactly... but JSR310, which learnt most things from joda-time
This has been in the Java8 release since last 6 months or so

---
Regards,
Saptarshi PURKAYASTHA

My Tech Blog:  http://sunnytalkstech.blogspot.com
You Live by CHOICE, Not by CHANCE


On 13 April 2013 13:33, Bob Jolliffe <bobjolliffe@xxxxxxxxx> wrote:

> On 13 April 2013 13:26, Saptarshi Purkayastha <sunbiz@xxxxxxxxx> wrote:
>
>> I think we should be Calendar agnostic in code and like most i18n capable
>> systems, not expect the timestamp in the database to be Calendar-specific
>> Postgres for instance uses Julian calendar internally. But still supports
>> many different systems, much more than standard SQL asks for.
>> Java similar uses long values, instead of Calendar-specific
>> representations.
>>
>> My point is, Java, Postgres (and MySQL) are well designed to work by
>> being calendar-agnostic.
>> Also, Joda-time<http://joda-time.sourceforge.net/apidocs/org/joda/time/chrono/package-summary.html>provides nice Chronology classes for different calendars, which we can use
>> for localized storing, retrieving or converting
>>
>
> Am I right in thinking joda-time is now integrated into the java.time
> package of java 8?
>
>
>>
>> For the JavaME app in one of the releases, we did have a custom calendar
>> component.
>> Having it display BS, Ethiopian or anything else, should be fairly easy.
>> But yes, very few low-end Java phones are locale specific.
>>
>>
>> ---
>> Regards,
>> Saptarshi PURKAYASTHA
>>
>> My Tech Blog:  http://sunnytalkstech.blogspot.com
>> You Live by CHOICE, Not by CHANCE
>>
>>
>> On 13 April 2013 10:36, Jason Pickering <jason.p.pickering@xxxxxxxxx>wrote:
>>
>>> Hi Saptarshi,
>>> Yes, I  cannot speculate really why DHIS2 only supports the Gregorian
>>> calendar, but this issue I think has been discussed a few times on the list
>>> before (perhaps for other countries).
>>>
>>> I feel the best approach would be to store all of the data with
>>> Gregorian dates, but what is shown through the web UI would be the calendar
>>> system of the particular instance. I am not even sure if databases like
>>> Postgres and MySQL (much less the operating system itself) would support
>>> non Gregorian calendar systems.
>>>
>>> As for data exchange, I see no immediate need for this, but if data is
>>> stored in Gregorian format ( I suppose the de facto international
>>> standard), then perhaps data exchange would be somewhat easier, but this is
>>> just speculation of course.
>>>
>>> Thanks for the link to the BS date picker. Does not seem to difficult to
>>> solve at least this problem.The bigger issue as I see it would be data
>>> entry through mobiles. At least the J2ME app uses the system calendar, and
>>> do not think that non-Gregorian systems are even supported on any phone?
>>>
>>> Best regards,
>>> Jason
>>>
>>>
>>>
>>>
>>>
>>> On Fri, Apr 12, 2013 at 5:16 PM, Saptarshi Purkayastha <sunbiz@xxxxxxxxx
>>> > wrote:
>>>
>>>> Hi Jason,
>>>>
>>>> When you say the system currently only support Gregorian calendar, I
>>>> wonder if that's a fact of JavaScript widgets
>>>> But while I was writing this email, a quick search in the code base
>>>> shows that we've instantiated Gregorian calendar at many places instead of
>>>> using the more localized Calendar.getInstance(). The first task would be
>>>> move to using this
>>>>
>>>> Secondly, is conversion between Gregorian dates and some other calendar
>>>> really required. If data is exchanged between different systems with
>>>> different calendars, this is important. But if we are storing a timestamp
>>>> in database, it should be fine to store it in the locale calendar. So I am
>>>> not too keen, unless really required to use the maps that allow co-relating
>>>> dates between calendar systems.
>>>>
>>>> Thirdly, there are quite a few (and fairly easy to write new JavaScript
>>>> calendars) to suite different locales. The care that we need to take is
>>>> being able to retrieve the correct calendar based on the set locale. A
>>>> simple BS calendar JS -
>>>> http://sajanmaharjan.com.np/my-works/nepali-datepicker-ui/
>>>>
>>>> ---
>>>> Regards,
>>>> Saptarshi PURKAYASTHA
>>>>
>>>> My Tech Blog:  http://sunnytalkstech.blogspot.com
>>>> You Live by CHOICE, Not by CHANCE
>>>>
>>>>
>>>> On 12 April 2013 12:56, Jason Pickering <jason.p.pickering@xxxxxxxxx>wrote:
>>>>
>>>>> Hi Devs,
>>>>> I have a question regarding non-Gregorian (Western) calendar systems.
>>>>> This issue has come up in a couple of different places which I know of,
>>>>> namely Ethiopia (Ethiopian calendar) and Afghanistan (Solar Hijri
>>>>> calendar). Currently, the system only supports a Gregorian calendar system,
>>>>> but I am trying to think of ways how we can support different
>>>>> ones, specifically the Bikram Sambat (BS) calendar system used in Nepal.
>>>>>
>>>>>
>>>>> There appears to be no easy way to convert between a Gregorian
>>>>> calendar. I dug out some code here
>>>>> <https://github.com/bahadurbaniya/Date-Converter-Bikram-Sambat-to-English-Date> which
>>>>> will convert between Gregorian dates and BS dates (but not the other way
>>>>> around). The approach is to use a look-up table, because of the fact that
>>>>> it seems to be difficult (if not impossible) to calculate the
>>>>> conversion algorithmically.
>>>>>
>>>>> This leads me to my question. Would it be possible that we consider
>>>>> adding a "Calendar system" to the application. The default would be
>>>>> "Gregorian", which is currently the case. The Second alternative might be
>>>>> "Bikram Sambat". This would require someone to prepopulate the system with
>>>>> periods (BS months, quarters and years)   which would be calculated through
>>>>> some other means (common Lisp code here<http://emr.cs.uiuc.edu/~reingold/calendar.l> which
>>>>> may be able to do this). These would be in Gregorian periods, but instead
>>>>> of the system calculating future periods, they would have to be
>>>>> pre-calculated and entered/imported into the system somehow.
>>>>>
>>>>> The second part of this (which I think may be more difficult) is the
>>>>> use of the JavaScript Gregorian calendar throughout the system. For data
>>>>> entry of aggregate data, it would not to be too problematic. But for the
>>>>> tracker module (and other places in the system), a Gregorian Javascript
>>>>> widget is used, and it would seem to be potentially difficult to replace
>>>>> this.
>>>>>
>>>>> Could the developers comment on feasibility and possible level of
>>>>> effort?
>>>>>
>>>>> Best regards,
>>>>> Jason
>>>>>
>>>>>
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>>>>>
>>>>
>>>
>>
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