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DBIx::Class::Helper::ResultSet::DateMethods1 - Work with dates in your RDBMS

DBIx::Class::Helper::ResultSet::DateMethods1(3pm) User Contributed Perl Documentation DBIx::Class::Helper::ResultSet::DateMethods1(3pm)

NAME

DBIx::Class::Helper::ResultSet::DateMethods1 - Work with dates in your RDBMS nicely

SYNOPSIS

 package MySchema::ResultSet::Bar;
 use strict;
 use warnings;
 use parent 'DBIx::Class::ResultSet';
 __PACKAGE__->load_components('Helper::ResultSet::DateMethods1');
 # in code using resultset
 # get count per year/month
 $rs->search(undef, {
    columns => {
       count => '*',
       year  => $rs->dt_SQL_pluck({ -ident => '.start' }, 'year'),
       month => $rs->dt_SQL_pluck({ -ident => '.start' }, 'month'),
    },
    group_by => [
       $rs->dt_SQL_pluck({ -ident => '.start' }, 'year'),
       $rs->dt_SQL_pluck({ -ident => '.start' }, 'month'),
    ],
 });
 
 # mysql
 (SELECT `me`.*, EXTRACT(MONTH FROM `me`.`start`), EXTRACT(YEAR FROM `me`.`start`) FROM `HasDateOps` `me` GROUP BY EXTRACT(YEAR FROM `me`.`start`), EXTRACT(MONTH FROM `me`.`start`))
 # SQLite
 (SELECT "me".*, STRFTIME('%m', "me"."start"), STRFTIME('%Y', "me"."start") FROM "HasDateOps" "me" GROUP BY STRFTIME('%Y', "me"."start"), STRFTIME('%m', "me"."start"))

DESCRIPTION

See "NOTE" in DBIx::Class::Helper::ResultSet for a nice way to apply it to your entire schema.
This ResultSet component gives the user tools to do mostly portable date manipulation in the database. Before embarking on a cross database project, take a look at "IMPLEMENTATION" to see what might break on switching databases.
This package has a few types of methods.
Search Shortcuts
These, like typical ResultSet methods, return another ResultSet. See "dt_before", "dt_on_or_before", "dt_on_or_after", and "dt_after".
The date helper
There is only one: "utc". Makes searching with dates a little easier.
SQL generators
These help generate more complex queries. The can be used in many different parts of "search" in DBIx::Class::ResultSet. See "utc_now", "dt_SQL_pluck", and "dt_SQL_add".

TYPES

Because these methods are so limited in scope they can be a bit more smart than typical "SQL::Abstract" trees.
There are "smart types" that this package supports.
vanilla scalars (1, "2012-12-12 12:12:12")
 
bound directly as untyped values
hashrefs with an "-ident" ("{ -ident => '.foo' }")
 
As usual this gets flattened into a column. The one special feature in this module is that columns starting with a dot will automatically be prefixed with "current_source_alias" in DBIx::Class::ResultSet.
DateTime objects
 
"DateTime" objects work as if they were passed to "utc".
"ScalarRef" ("\'NOW()'")
 
As usual in "DBIx::Class", "ScalarRef"'s will be flattened into regular SQL.
"ArrayRefRef" ("\["SELECT foo FROM bar WHERE id = ?", [{}, 1]]")
 
As usual in "DBIx::Class", "ArrayRefRef"'s will be flattened into SQL with bound values.
Anything not mentioned in the above list will explode, one way or another.

IMPLEMENTATION

The exact details for the functions your database engine provides.
If a piece of functionality is flagged with ⚠, it means that the feature in question is not portable at all, and only supported on that engine.

"SQL Server"

"utc_now" - GETUTCDATE <http://msdn.microsoft.com/en-us/library/ms178635.aspx>
"dt_SQL_pluck" - DATEPART <http://msdn.microsoft.com/en-us/library/ms174420.aspx>
 
Supported units
year
quarter
month
day_of_year
day_of_month
week
day_of_week
hour
minute
second
millisecond
nanosecond ⚠
non_iso_day_of_week
 
SQL Server offers both "ISO_WEEK" and "weekday". For interop reasons "weekday" uses the "ISO_WEEK" version.
timezone_as_minutes ⚠
"dt_SQL_add" - DATEADD <http://msdn.microsoft.com/en-us/library/ms186819.aspx>
 
Supported units
year
quarter
month
day
week
hour
minute
second
millisecond
nanosecond ⚠
iso_day_of_week
timezone_as_minutes ⚠

"SQLite"

"utc_now" - DATETIME('now') <https://www.sqlite.org/lang_datefunc.html>
"dt_SQL_pluck" - STRFTIME <https://www.sqlite.org/lang_datefunc.html>
 
Note: "SQLite"'s pluck implementation pads numbers with zeros, because it is implemented on based on a formatting function. If you want your code to work on SQLite you'll need to strip off (or just numify) what you get out of the database first.
 
Available units
month
day_of_month
year
hour
day_of_year
minute
second
day_of_week
week
julian_day ⚠
seconds_since_epoch
fractional_seconds ⚠
"dt_SQL_add" - DATETIME <https://www.sqlite.org/lang_datefunc.html>
 
Available units
day
hour
minute
second
month
year

"PostgreSQL"

"utc_now" - CURRENT_TIMESTAMP <http://www.postgresql.org/docs/current/static/functions-datetime.html#FUNCTIONS-DATETIME-CURRENT>
"dt_SQL_pluck" - date_part <http://www.postgresql.org/docs/current/static/functions-datetime.html#FUNCTIONS-DATETIME-EXTRACT>
 
Available units
century ⚠
decade ⚠
day_of_month
day_of_week
day_of_year
seconds_since_epoch
hour
iso_day_of_week
iso_year
microsecond
millenium ⚠
millisecond
minute
month
quarter
second
timezone ⚠
timezone_hour ⚠
timezone_minute ⚠
week
year
"dt_SQL_add" - Addition and interval <http://www.postgresql.org/docs/current/static/functions-datetime.html#OPERATORS-DATETIME-TABLE>
 
To be clear, it ends up looking like: "("some_column" + 5 * interval '1 minute')"
 
Available units
century ⚠
decade ⚠
day
hour
microsecond ⚠
millisecond
minute
month
second
week
year

"MySQL"

"utc_now" - UTC_TIMESTAMP <https://dev.mysql.com/doc/refman/5.1/en/date-and-time-functions.html#function_utc-timestamp>
"dt_SQL_pluck" - EXTRACT <https://dev.mysql.com/doc/refman/5.1/en/date-and-time-functions.html#function_extract>
 
Available units
microsecond
second
minute
hour
day_of_month
week
month
quarter
year
second_microsecond ⚠
minute_microsecond ⚠
minute_second ⚠
hour_microsecond ⚠
hour_second ⚠
hour_minute ⚠
day_microsecond ⚠
day_second ⚠
day_minute ⚠
day_hour ⚠
year_month ⚠
"dt_SQL_add" - DATE_ADD <https://dev.mysql.com/doc/refman/5.1/en/date-and-time-functions.html#function_date-add>
 
Available units
microsecond
second
minute
hour
day
week
month
quarter
year

"Oracle"

"utc_now" - sys_extract_utc(SYSTIMESTAMP) <http://docs.oracle.com/cd/B19306_01/server.102/b14200/functions167.htm>
"dt_SQL_pluck" - EXTRACT
 
Available units
second
minute
hour
day_of_month
month
year
"dt_SQL_add" - Addition and NUMTODSINTERVAL <http://docs.oracle.com/cd/B19306_01/server.102/b14200/functions103.htm>
 
To be clear, it ends up looking like: "("some_column" + NUMTODSINTERVAL(4, 'MINUTE')"
 
Available units
second
minute
hour
day

CONTRIBUTORS

These people worked on the original implementation, and thus deserve some credit for at least providing me a reference to implement this based off of:
Alexander Hartmaier (abraxxa) for Oracle implementation details
Devin Austin (dhoss) for Pg implementation details
Rafael Kitover (caelum) for providing a test environment with lots of DBs

WHENCE dt_SQL_diff?

The original implementation of these date helpers (originally dubbed date operators) included a third operator called "diff". It existed to subtract one date from another and return a duration. After using it a few times and getting bitten every time, I decided to stop using it and instead compare against actual dates always. If someone can come up with a good use case I am interested in re-implementing "dt_SQL_diff", but I worry that it will be very unportable and generally not very useful.

METHODS

utc

 $rs->search({
   'some_date' => $rs->utc($datetime),
 })->all
Takes a DateTime object, updates the "time_zone" to "UTC", and formats it according to whatever database engine you are using.
Dies if you pass it a date with a "floating time_zone".

utc_now

Returns a "ScalarRef" representing the way to get the current date and time in "UTC" for whatever database engine you are using.

dt_before

 $rs->dt_before({ -ident => '.start' }, { -ident => '.end' })->all
Takes two values, each an expression of "TYPES".

dt_on_or_before

 $rs->dt_on_or_before({ -ident => '.start' }, DateTime->now)->all
Takes two values, each an expression of "TYPES".

dt_on_or_after

 $rs->dt_on_or_after(DateTime->now, { ident => '.end' })->all
Takes two values, each an expression of "TYPES".

dt_after

 $rs->dt_after({ ident => '.end' }, $rs->get_column('datecol')->as_query)->all
Takes two values, each an expression of "TYPES".

dt_SQL_add

 # which ones start in 3 minutes?
 $rs->dt_on_or_after(
    { ident => '.start' },
    $rs->dt_SQL_add($rs->utc_now, 'minute', 3)
 )->all
Takes three arguments: a date conforming to "TYPES", a unit, and an amount. The idea is to add the given unit to the datetime. See your "IMPLEMENTATION" for what units are accepted.

dt_SQL_pluck

 # get count per year
 $rs->search(undef, {
    columns => {
       count => '*',
       year  => $rs->dt_SQL_pluck({ -ident => '.start' }, 'year'),
    },
    group_by => [$rs->dt_SQL_pluck({ -ident => '.start' }, 'year')],
 })->hri->all
Takes two arguments: a date conforming to "TYPES" and a unit. The idea is to pluck a given unit from the datetime. See your "IMPLEMENTATION" for what units are accepted.

AUTHOR

Arthur Axel "fREW" Schmidt <frioux+cpan@gmail.com> This software is copyright (c) 2017 by Arthur Axel "fREW" Schmidt.
This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.
2017-07-03 perl v5.24.1