The compare operator should be added to the Mathematics section of the Filter Operators <https://tiddlywiki.com/#Filter%20Operators> table, I had no idea it existed until I saw Eric's answer above.
On Sunday, July 4, 2021 at 2:57:05 PM UTC-7 Eric Shulman wrote: > On Sunday, July 4, 2021 at 1:09:10 PM UTC-7 [email protected] wrote: > >> I have a filed that in a tiddler that has a date value, i would like to >> have button to add one hour to the date value , is this possible ? >> > > By "date value", do you actually mean a full "datetime" value, which in TW > is stored as a 17-digit number (YYYYMMDDhhmmssXXX)? Assuming that is the > case, it can be done, but it's not as simple as it may seem. > > For instance, if the stored datetime is 20210704133000000 (i.e., 1:30pm on > July 4, 2021), then it is relatively easy (though not trivial) to add an > hour, like this: > <$button> add an hour > <$vars > before={{{ [{!!stored_datetime}split[]first[8]join[]] }}} > hour={{{ [{!!stored_datetime}split[]rest[8]first[2]join[]] }}} > after={{{ [{!!stored_datetime}split[]rest[10]join[]] }}}> > <$vars newhour={{{ [<hour>add[1]pad[2]] }}}> > <$action-setfield stored_datetime={{{ > [<before>addsuffix<newhour>addsuffix<after>] }}} /> > </$vars> > </$vars> > </$button> > > * First, break the datetime value into parts to isolate the hour number: > ** Use split[] to break the datetime value into individual digits, and > join the first[8] digits to get the date portion. > ** Use rest[8] to get the remaining digits and join the first[2] of those > digits to get the hour number. > ** Use rest[10] to get the digits following the hour number, and join > those to get the minutes, seconds and millisecond portion. > * Next, add 1 to the hour number and apply pad[2] to the result to ensure > it is 2 digits with a leading 0 if needed. > * Then, reassemble the parts to give the new datetime value and update the > field value. > > However... *this is not sufficient to handle all possible stored_datetime > values*. > > For example, suppose that the stored datetime is 20210704233000000 (i.e., > 11:30pm on July 4, 2021). Simply adding an hour as shown above would give > 20210704243000000. But that is not a valid datetime value, as the hours > portion must be between 00 and 23. The correct result would actually be > 20210705003000000 (i.e., 12:30am on July 5, 2021). Thus, we need to handle > "hour overflow" to set the hour number to 00 and add 1 to the day number. > > But... even that is not enough. Suppose the stored datetime is > 20210731233000000 (i.e., 11:30pm on July 31, 2021). Then adding 1 hour > should result in 20210801003000000 (i.e., 12:30am on August 1, 2021). Thus, > we not only need to handle "hour overflow" as above, but also "date > overflow" to add 1 to the month number. > > Complicating this is that the number of days per month varies, so the > "date overflow" handling needs to take into account the specified month to > know how many days it has. Further complicating this is leap years, in > which the number of days in February is 29 rather than 28, but only for > years that are divisible by 4 but not divisible by 100, unless also > divisible by 400. > > Lastly, we need also to handle "year overflow". If the stored datetime is > 20211231233000000 (i.e., 11:30pm on December 31, 2021). Then adding 1 hour > should result in 20220101003000000 (i.e., 12:30am on January 1, 2022). > > Obviously, handling all of these issues requires some complex conditional > calculations. Fortunately, *I've already tackled this problem > in http://tiddlytools.com/timer.html#TiddlyTools%2FTime%2FClocks > <http://tiddlytools.com/timer.html#TiddlyTools%2FTime%2FClocks>*. The > clock_adjustForTimezone() macro takes the current datetime and adds or > subtracts a "timezone offset" value to give a new datetime value. For your > purposes, rather than using the current datetime, you want to get the > stored_datetime value, and instead of using a "timezone offset", you want > to use a specified offset of 1 hour (i.e., "+01:00") > > Here's a modified version of clock_adjustForTimezone() that does what you > need: > \define adjust_time() > \whitespace trim > <!-- split time into parts --> > <$vars yyyy={{{ [<time>split[]first[4]join[]] }}}> > <$vars mm={{{ [<time>split[]first[6]last[2]join[]] }}}> > <$vars dd={{{ [<time>split[]first[8]last[2]join[]] }}}> > <$vars hh={{{ [<time>split[]first[10]last[2]join[]] }}}> > <$vars min={{{ [<time>split[]first[12]last[2]join[]] }}}> > <$vars ssxxx={{{ [<time>split[]last[5]join[]] }}}> > <!-- apply offset "+hh:mm" or "-hh:mm" --> > <$vars sign={{{ [<offset>split[]first[]] }}}> > <$vars offhh={{{ [<offset>split[]first[3]join[]] }}}> > <$vars offmin={{{ [<offset>split[]last[2]join[]addprefix<sign>] }}}> > <$vars hh={{{ [<hh>add<offhh>] }}}> > <$vars min={{{ [<min>add<offmin>] }}}> > <!-- adjust days per month for leap year --> > <$set name="leap" value={{{ [<yyyy>remainder[4]match[0]then[yes]] }}}> > <$set name="dpm" value="31 28 31 30 31 30 31 31 30 31 30 31"> <!-- days > per month --> > <$set name="dpm" filter="[<leap>!match[]]" value="31 29 31 30 31 30 31 31 > 30 31 30 31" emptyValue=<<dpm>>> > <!-- adjust hours/minutes for minutes wraparound --> > <$set name="hh" filter="[<min>compare:integer:lt[0]]" value={{{ > [<hh>subtract[1]] }}} emptyValue=<<hh>>> > <$set name="hh" filter="[<min>compare:integer:gteq[60]]" value={{{ > [<hh>add[1]] }}} emptyValue=<<hh>>> > <$set name="min" filter="[<min>compare:integer:lt[0]]" value={{{ > [<min>add[60]] }}} emptyValue=<<min>>> > <$set name="min" filter="[<min>compare:integer:gteq[60]]" value={{{ > [<min>subtract[60]] }}} emptyValue=<<min>>> > <!-- adjust date/hours for hours wraparound --> > <$set name="dd" filter="[<hh>compare:integer:lt[0]]" value={{{ > [<dd>subtract[1]] }}} emptyValue=<<dd>>> > <$set name="dd" filter="[<hh>compare:integer:gteq[24]]" value={{{ > [<dd>add[1]] }}} emptyValue=<<dd>>> > <$set name="hh" filter="[<hh>compare:integer:lt[0]]" value={{{ > [<hh>add[24]] }}} emptyValue=<<hh>>> > <$set name="hh" filter="[<hh>compare:integer:gteq[24]]" value={{{ > [<hh>subtract[24]] }}} emptyValue=<<hh>>> > <!-- adjust month/date for date wraparound --> > <$set name="dm" value={{{ [<dpm>split[ ]nth<mm>] }}}> <!-- days in this > month --> > <$set name="mm" filter="[<dd>compare:integer:lteq[0]]" value={{{ > [<mm>subtract[1]] }}} emptyValue=<<mm>>> > <$set name="mm" filter="[<dd>compare:integer:gt<dm>]" value={{{ > [<mm>add[1]] }}} emptyValue=<<mm>>> > <$set name="dd" filter="[<dd>compare:integer:lteq[0]]" value={{{ > [<dpm>split[ ]nth<mm>] }}} emptyValue=<<dd>>> > <$set name="dd" filter="[<dd>compare:integer:gt<dm>]" value={{{ > [[1]] }}} emptyValue=<<dd>>> > <!-- adjust year/date/month for month wraparound --> > <$set name="yyyy" filter="[<mm>compare:integer:lteq[0]]" value={{{ > [<yyyy>subtract[1]] }}} emptyValue=<<yyyy>>> > <$set name="yyyy" filter="[<mm>compare:integer:gt[12]]" value={{{ > [<yyyy>add[1]] }}} emptyValue=<<yyyy>>> > <$set name="dd" filter="[<mm>compare:integer:lteq[0]]" value={{{ > [[31]] }}} emptyValue=<<dd>>> > <$set name="dd" filter="[<mm>compare:integer:gt[12]]" value={{{ > [[1]] }}} emptyValue=<<dd>>> > <$set name="mm" filter="[<mm>compare:integer:lteq[0]]" value={{{ > [[12]] }}} emptyValue=<<mm>>> > <$set name="mm" filter="[<mm>compare:integer:gt[12]]" value={{{ > [[1]] }}} emptyValue=<<mm>>> > <!-- zero-pad and assemble new time --> > <$vars mm={{{ [<mm>pad[2]] }}} dd={{{ [<dd>pad[2]] }}} hh={{{ > [<hh>pad[2]] }}} min={{{ [<min>pad[2]] }}}> > {{{ > [<yyyy>addsuffix<mm>addsuffix<dd>addsuffix<hh>addsuffix<min>addsuffix<ssxxx>] > }}} > \end > > and here's a button that invokes the above to update the stored_datetime > field value: > > <$button> add an hour > <$vars time={{!!stored_datetime}} offset="+01:00"> > <$wikify name="newtime" text=<<adjust_time>>> > <$action-setfield stored_datetime=<<newtime>> /> > </$wikify> > </$vars> > </$button> > > enjoy, > -e > -- You received this message because you are subscribed to the Google Groups "TiddlyWiki" group. 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