NAME

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

STATUS

Coverage 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 <srchulo@cpan.org>

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