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

  • "dt_SQL_pluck" - DATEPART

    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

    Supported units

    • year

    • quarter

    • month

    • day

    • week

    • hour

    • minute

    • second

    • millisecond

    • nanosecond ⚠

    • iso_day_of_week

    • timezone_as_minutes ⚠

SQLite

  • "utc_now" - DATETIME('now')

  • "dt_SQL_pluck" - STRFTIME

    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

    Available units

    • day

    • hour

    • minute

    • second

    • month

    • year

PostgreSQL

  • "utc_now" - CURRENT_TIMESTAMP

  • "dt_SQL_pluck" - date_part

    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

    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

  • "dt_SQL_pluck" - 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

    Available units

    • microsecond

    • second

    • minute

    • hour

    • day

    • week

    • month

    • quarter

    • year

Oracle

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_subtract

Same as dt_SQL_add, but subtracts the amount.

Only confirmed to work with Postgres, MySQL and SQLite. It should work with Oracle and MSSQL, but due to lack of access to those DB engines the implementation was done only based on docs.

This method was implemented by Thomas Klausner and sponsored by Ctrl O.

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>

COPYRIGHT AND LICENSE

This software is copyright (c) 2019 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.