Mojo::Collection::Role::Transform - Transformations for Mojo::Collection
my $c = Mojo::Collection->new(
{
name => 'Bob',
age => 23,
favorite_color => 'blue',
},
{
name => 'Alice',
age => 24,
favorite_color => 'blue',
},
{
name => 'Eve',
age => 27,
favorite_color => 'green',
},
)->with_roles('+Transform');
# hash key is name, value is the original hash
my $name_to_person = $c->hashify(sub { $_->{name} });
# 23
say $name_to_person->{Bob}{age};
# 27
say $name_to_person->{Eve}{age};
# set your own value
my $name_to_favorite_color = $c->hashify(sub { $_->{name} }, sub { $_->{favorite_color} });
# blue
say $name_to_favorite_color->{Bob};
# green
say $name_to_favorite_color->{Eve};
# collect values with the same key in a Mojo::Collection
my $favorite_color_to_collection = $c->hashify_collect(sub { $_->{favorite_color} });
# $favorite_color_to_collection->{blue} contains Mojo::Collection of Bob and Alice hashes
# $favorite_color_to_collection->{green} contains Mojo::Collection of Eve hash
# says Bob, then Alice
for my $person ($favorite_color_to_collection->{blue}->each) {
say $person->{name};
}
# Create a Mojo::Collection of Mojo::Collections, where all values in each inner
# Mojo::Collection share the same key
my $collections_by_favorite_color = $c->collect_by(sub { $_->{favorite_color} });
for my $favorite_color_collection ($collections_by_favorite_color->each) {
say $favorite_color_collection->[0]->{favorite_color};
for my $person ($favorite_color_collection->each) {
say "\t$person->{name}";
}
}
# output is
# blue
# Bob
# Alice
# green
# Eve
Mojo::Collection::Role::Transform provides methods that allow you to transform your Mojo::Collection in meaningful and flexible ways.
-
hashify($get_keys_sub, [$get_value_sub])
my $c = Mojo::Collection->new( { name => 'Bob', age => 23, favorite_color => 'blue', }, { name => 'Alice', age => 24, favorite_color => 'blue', }, { name => 'Eve', age => 27, favorite_color => 'green', }, )->with_roles('+Transform');
hash key is name, value is the original hash
my $name_to_person = $c->hashify(sub { $_->{name} });
23
say $name_to_person->{Bob}{age};
27
say $name_to_person->{Eve}{age};
set your own value
my $name_to_favorite_color =
$c->hashify(sub { $ ->{name} }, sub { $->{favorite_color} });blue
say $name_to_favorite_color->{Bob};
green
say $name_to_favorite_color->{Eve};
return multiple keys as a list to create a multiple nested hashes based on the returned keys and their order
my $name_to_age_favorite_color =
$c->hashify(sub { @$ {qw(name age)} }, sub { $->{favorite_color} });blue
say $name_to_favorite_color->{Bob}{23};
green
say $name_to_favorite_color->{Eve}{27};
"hashify" allows you to transform a Mojo::Collection into a single key or multi-key hash based on its elements. A unique key or list of keys may only have one value, so for any duplicate keys, the final element seen with that key will be the one that sets the value.
"get_keys" is required and must return a single key or a list of keys. The return value of "get_keys" will be the keys used to ultimately access the value that is returned by "get_value" for the same element.
# return single key
my $hash = $c->hashify(sub { $_->{name} });
my $value = $hash->{$name};
# return multiple keys
my $hash = $c->hashify(sub { $_->{name}, $_->{age} });
my $value = $hash->{$name}{$age};
The current element is available via $_, or as the first argument to "get_keys".
"get_value" must return a single value for the current element in the Mojo::Collection.
my $name_to_age = $c->hashify(sub { $_->{name} }, sub { $_->{age} });
my $age = $name_to_age->{Bob};
The default is to return the current element:
# default get_value
sub { $_ }
# not passing in get_value uses the above subroutine to return the current collection element, in this case a hash
my $name_to_person = $c->hashify(sub { $_->{name} });
my $age = $name_to_person->{Bob}{age};
The current element is available via $_, or as the first argument to "get_value".
-
hashify_collect($get_keys_sub, [$get_values_sub])
my $c = Mojo::Collection->new( { name => 'Bob', age => 23, favorite_color => 'blue', }, { name => 'Alice', age => 24, favorite_color => 'blue', }, { name => 'Eve', age => 27, favorite_color => 'green', }, )->with_roles('+Transform');
collect values with the same key in a Mojo::Collection
my $favorite_color_to_collection = $c->hashify_collect(sub { $_->{favorite_color} });
$favorite_color_to_collection->{blue} contains Mojo::Collection of Bob and Alice hashes
$favorite_color_to_collection->{green} contains Mojo::Collection of Eve hash
says Bob, then Alice
for my $person ($favorite_color_to_collection->{blue}->each) { say $person->{name}; }
provide your own get_values sub
my $favorite_color_to_names =
$c->hashify_collect(sub { $ ->{favorite_color} }, sub { $->{name} });$favorite_color_to_names->{blue} contains Mojo::Collection of 'Bob' and 'Alice'
$favorite_color_to_names->{green} contains Mojo::Collection of 'Eve'
return multiple values
my $favorite_color_to_names_and_ages =
$c->hashify_collect(sub { $ ->{favorite_color} }, sub { $->{name}, $_->{age} });$favorite_color_to_names_and_ages->{blue} contains Mojo::Collection of 'Bob', 23, 'Alice', 24
$favorite_color_to_names_and_ages->{green} contains Mojo::Collection of 'Eve', 27
"hashify_collect" allows you to transform a Mojo::Collection into a single key or multi-key hash where the final value is a Mojo::Collection with all elements that match that key. "get_values" allows you to control which values are collected in the Mojo::Collection.
"get_keys" is required and must return a single key or a list of keys. The return value of "get_keys" will be the keys used to ultimately access the Mojo::Collection of values that are returned by "get_values" for each element.
# return single key
my $hash = $c->hashify(sub { $_->{name} });
my $collection = $hash->{$name};
# return multiple keys
my $hash = $c->hashify(sub { $_->{name}, $_->{age} });
my $collection = $hash->{$name}{$age};
The current element is available via $_, or as the first argument to "get_keys".
"get_values" may return one or more values as a list for the current element in the Mojo::Collection.
# return single value
my $name_to_ages = $c->hashify(sub { $_->{name} }, sub { $_->{age} });
my $ages_collection = $name_to_ages->{Bob};
# return multiple values
my $name_to_ages_and_favorite_colors = $c->hashify(sub { $_->{name} }, sub { $_->{age}, $_->{favorite_color} });
my $ages_and_favorite_colors_collection = $name_to_ages_and_favorite_colors->{Bob};
The default is to return the current element:
# default get_value
sub { $_ }
# not passing in get_value uses the above subroutine to return the current collection element, in this case a hash
my $name_to_persons = $c->hashify(sub { $_->{name} });
my $person_collection = $name_to_persons->{Bob};
The current element is available via $_, or as the first argument to "get_values".
# trivial example where returned values are wrapped in arrayrefs to demonstrate flatten
my $name_to_ages = $c->hashify({flatten => 1}, sub { $_->{name} }, sub { [$_->{age}] });
The "flatten" option flattens each resulting Mojo::Collection, meaning that it flattens nested collections/arrays recursively and creates a new collection with all elements. See "flatten" in Mojo::Collection for more details.
Internally, "flatten" is implemented differently for performance, but the end result is the same.
-
collect_by($get_keys_sub, [$get_values_sub])
my $c = Mojo::Collection->new( { name => 'Bob', age => 23, favorite_color => 'blue', }, { name => 'Alice', age => 24, favorite_color => 'blue', }, { name => 'Eve', age => 27, favorite_color => 'green', }, )->with_roles('+Transform');
Create a Mojo::Collection of Mojo::Collections, where all values in each inner
Mojo::Collection share the same key
my $collections_by_favorite_color = $c->collect_by(sub { $_->{favorite_color} }); for my $favorite_color_collection ($collections_by_favorite_color->each) { say $favorite_color_collection->[0]->{favorite_color};
for my $person ($favorite_color_collection->each) { say "\t$person->{name}"; }}
output is
blue
Bob
Alice
green
Eve
collect by multiple keys
uses favorite_color and age as the keys
my $collections_by_favorite_color_and_age =
$c->collect_by(sub { $ ->{favorite_color}, $->{age} });
"collect_by" allows you to transform a Mojo::Collection into a Mojo::Collection of Mojo::Collections, where all elements of the inner collections share the same single key or list of keys. "get_values" allows you to control which values are collected in the Mojo::Collection.
"get_keys" is required and must return a single key or a list of keys. The return value of "get_keys" will be the keys used group values that are returned by "get_values" into each inner Mojo::Collection.
# return single key
my $collections = $c->hashify(sub { $_->{name} });
# return multiple keys
my $collections = $c->hashify(sub { $_->{name}, $_->{age} });
The current element is available via $_, or as the first argument to "get_keys".
"get_values" may return one or more values as a list for the current element in the Mojo::Collection.
# return single value
my $collections_of_age = $c->hashify(sub { $_->{name} }, sub { $_->{age} });
# i.e.
# [ [23], [24], [27] ]
# return multiple values
my $collections_of_age_and_favorite_color = $c->hashify(sub { $_->{name} }, sub { $_->{age}, $_->{favorite_color} });
# i.e.
# [ [23, 'blue'], [24, 'blue'], [27, 'green'] ]
The default is to return the current element:
# default get_value
sub { $_ }
# not passing in get_value uses the above subroutine to return the current collection element, in this case a hash
my $collections = $c->hashify(sub { $_->{name} });
# i.e.
# [ [{ name => 'Bob', ...}], [{ name => 'Alice', ...}], [{name => 'Eve', ...}] ]
The current element is available via $_, or as the first argument to "get_values".
# trivial example where returned values are wrapped in arrayrefs to demonstrate flatten
my $collections = $c->hashify({flatten => 1}, sub { 'key' }, sub { [$_->{age}] });
# i.e.
# [ [23, 24, 27] ]
The "flatten" option flattens each inner Mojo::Collection, meaning that it flattens nested collections/arrays recursively and creates a new collection with all elements. See "flatten" in Mojo::Collection for more details.
Internally, "flatten" is implemented differently for performance, but the end result is the same.
Adam Hopkins srchulo@cpan.org
Copyright 2019- Adam Hopkins
This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.