NAME

   Mojo::Collection::Role::Transform - Transformations for
   Mojo::Collection

STATUS

SYNOPSIS

     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

DESCRIPTION

   Mojo::Collection::Role::Transform provides methods that allow you to
   transform your Mojo::Collection in meaningful and flexible ways.

METHODS

hashify

   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

   "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

   "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

   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

   "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

   "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".

 OPTIONS

  flatten

     # 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

   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

   "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

   "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".

 OPTIONS

  flatten

     # 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.

AUTHOR

   Adam Hopkins <[email protected]>

COPYRIGHT

   Copyright 2019- Adam Hopkins

LICENSE

   This library is free software; you can redistribute it and/or modify it
   under the same terms as Perl itself.

SEE ALSO

     * * Mojo::Collection

     * * "with_roles" in Mojo::Base

     * * Role::Tiny

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