Rails automatically appends a dummy date when you use the TIME type on your database. My point is: if you are using a time data type on your database, you are doing that exactly because you don't want the date included.
Anyway, I am storing a integer column with the total seconds on the database and then transforming that with composed_of. Is there a better way to do that? Anyone know if there is a gem or something to handle cases like these?
I just use a datetime column and ignore the date part.
Colin
reu wrote:
Rails automatically appends a dummy date when you use the TIME type on your database. My point is: if you are using a time data type on your database, you are doing that exactly because you don't want the date included.
Anyway, I am storing a integer column with the total seconds on the database and then transforming that with composed_of. Is there a better way to do that? Anyone know if there is a gem or something to handle cases like these?
Time without data is useless and extremely prone to error. Internally time is stored as millisecond offsets from a reference date (e.g. UNIX time is the number of milliseconds from midnight January 1, 1970 UTC). The date and time related objects in Ruby depend on this underlying offset.
a value of 14:00 is meaningless without relating that to some date, in some time zone, and applying the geopolitical rules for daylight savings (or other adjustments to the normal flow of time).
I personally don't know why MySQL even bothers providing a TIME field type.
Of course, as always, I could be missing some specific use case for it.
Robert Walker wrote:
Time without data is useless and extremely prone to error. Internally time is stored as millisecond offsets from a reference date (e.g. UNIX time is the number of milliseconds from midnight January 1, 1970 UTC). The date and time related objects in Ruby depend on this underlying offset.
Correction: Time without date...
Repeating events, "Tuesdays at 4:00pm" for example.
PostgreSQL also provides a time field type where no date is stored.
Greg Donald wrote:
I personally don't know why MySQL even bothers providing a TIME field type.
Of course, as always, I could be missing some specific use case for it.
Repeating events, "Tuesdays at 4:00pm" for example.
PostgreSQL also provides a time field type where no date is stored.
As I said meaningless without applying the date part to it. If today is Saturday, and the event is scheduled at 4:00 p.m. Tuesday, what happens if the time changes to, or from, daylight savings time at 2:00 a.m. Sunday. The value "4:00 p.m." must be translated based on the specific date the Tuesday lands on. Might as well just store the time as a string at that point. The time has no value as a Time (object) (i.e it must be parsed based on the date anyway).
Robert Walker wrote:
As I said meaningless without applying the date part to it. If today is Saturday, and the event is scheduled at 4:00 p.m. Tuesday, what happens if the time changes to, or from, daylight savings time at 2:00 a.m. Sunday. The value "4:00 p.m." must be translated based on the specific date the Tuesday lands on. Might as well just store the time as a string at that point. The time has no value as a Time (object) (i.e it must be parsed based on the date anyway).
I suppose though that the TIME field would provide some basic validation, which would be it's only benefit as far as I see it.
If I have a date at 4pm on Tuesday, the date is at 4pm regardless of
the state of daylight savings time 
Michael Pavling wrote:
Not all apps require multi-timezone capabilities. Like when everyone is in one office, using the same calendar app.
Dreaming up edge cases isn't going to make those time (without date) fields any less useful to those of us who use them.
Hopefully she'll be in the same as me wherever it is, otherwise it probably won't be a very good date.
But, if there is a risk in the implementation that timezones confusion could cause problems, then store a timezone value in addition to the time. There's not that much more confusion with timezones caused when storing just time than with datetime.
Robert Walker wrote:
If I have a date at 4pm on Tuesday, the date is at 4pm regardless of the state of daylight savings time
In what time zone?
My point being again that any interpretation of whatever gets stored as a time only, must be translated into a Time or DateTime object based on a specific date, in a specific locale. That's really all I'm saying. 4:00 p.m. from your locale may mean 7:30 p.m. in my locale. It's dependent on geopolitical rules.
Lots of web apps, certainly dozens I've built, are just for a single company, with a single office, in a single time zone.
That's great that you build apps where time zone does matter, and that you build apps for companies where time zone does matter, but it doesn't make the time (without date) field any less useful to me.
Greg Donald wrote:
Not all apps require multi-timezone capabilities. Like when everyone is in one office, using the same calendar app.
Dreaming up edge cases isn't going to make those time (without date) fields any less useful to those of us who use them.
You're still missing my point entirely. We're talking about representing a time with a Time object. It matters not whether you need to support multi-timezone or not. AFAIK there is no Ruby object that represents time without date. The Time object represents an instant in date/time, not some offset from midnight.
I hope that makes my meaning more clear.
You're still missing my point entirely. We're talking about representing a time with a Time object. It matters not whether you need to support multi-timezone or not.
I agree, you brought it up.
AFAIK there is no Ruby object that represents time without date.
It's called a Fixnum, works great.
> In what time zone?
To produce a specific part it takes our machine 1 hour and 15 minutes => 01:15:00 And I would like to store this value in the database. Btw it wouldn't matter if this part will be produced on Mondays or Tuesdays or in which time zone the factory is..
Greg Donald wrote:
You're still missing my point entirely. We're talking about representing a time with a Time object. It matters not whether you need to support multi-timezone or not.
I agree, you brought it up.
AFAIK there is no Ruby object that represents time without date.
It's called a Fixnum, works great.
Yep. I apologize for the misunderstanding. I knew we were arguing the same side of the issue. It just took me a few tries to get to the heart of the matter.
Fixnum (INTEGER) is exactly what I typically use as well (i.e. an offset from midnight).
reu wrote:
Rails automatically appends a dummy date when you use the TIME type on your database. My point is: if you are using a time data type on your database, you are doing that exactly because you don't want the date included.
My original intent was an effort to explain this question in original post. Rails is applying a "dummy date" because it must. However, that time representation is subject to interpretation. And that depends on what time zone Rails applies to that interpretation.
Rails automatically appends a dummy date when you use the TIME type on your database. My point is: if you are using a time data type on your database, you are doing that exactly because you don't want the date included.
Anyway, I am storing a integer column with the total seconds on the database and then transforming that with composed_of. Is there a better way to do that? Anyone know if there is a gem or something to handle cases like these?
Time without date is useless and extremely prone to error. Internally time is stored as millisecond offsets from a reference date (e.g. UNIX time is the number of milliseconds from midnight January 1, 1970 UTC). The date and time related objects in Ruby depend on this underlying offset.
a value of 14:00 is meaningless without relating that to some date, in some time zone, and applying the geopolitical rules for daylight savings (or other adjustments to the normal flow of time).
Just for the sake of argument... how about the time it takes runners to finish a marathon? Sure you could use seconds as an integer field, but time without date make sense...
I agree that "4pm" is kind of pointless, but "16 hours" can be handy.
If only to save me from having to convert from seconds to hh:mm:ss and back, etc...
-philip
Philip Hallstrom wrote in post #937228:
Just for the sake of argument... how about the time it takes runners to finish a marathon? Sure you could use seconds as an integer field, but time without date make sense...
I'm currently developing application, where I need to store beginning date (date only, without time) and amount of time passed.
I found a gem, that deals with 'time without date' issue:
It can be useful in some cases.
So we have to differentiate between
“Time” which means Point of Time in a specific day, and
“Duration” which means the difference between two Points in Time
Is there a “Duration” gem for RoR ?
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