slice(*keys)

Slices a hash to include only the given keys This is useful for limiting an options hash to valid keys before passing to a method:

def search(criteria = {}) assert_valid_keys(:mass, :velocity, :time) end search(optionsslice(:mass, :velocity, :time))

If you have an array of keys you want to limit to, you should splat them:

valid_keys = [:mass, :velocity, :time] search(optionsslice(*valid_keys))

slice!(*keys)

>> {:a => 1, :b => 2, :c => 3, :d => 4}slice!(:a, :b) => {:c => 3, :d =>4}

B239 active support/core ext/object/

to param(namespace = nil)

Converts a hash into a string suitable for use as a URL query string An optional namespace can be passed to enclose the param names (see example below)

>> { :name => 'David', :nationality => 'Danish' }to_param => "name=David&nationality=Danish" >> { :name => 'David', :nationality => 'Danish' }to_param('user') => "user[name]=David&user[nationality]=Danish"

B2310 active support/core ext/object/

Collects the keys and values of a hash and composes a URL-style query string using ampersand and equal-sign characters

>> {:foo => "hello", :bar => "goodbye"}to_query => "bar=goodbye&foo=hello"

As stated in the source file:

This class has dubious semantics and we only have it so that people can write params[:key] instead of params['key']

B25 ActiveSupport::Inflector::

The Inflections class transforms words from singular to plural, class names to table names, modularized class names to ones without, and class names to foreign keys The default inflections for pluralization, singularization, and uncountable words are kept in activesupport/lib/active_support/inflectionsrb and reproduced here for reference

module ActiveSupport Inflectorinflections do |inflect| inflectplural(/$/, 's') inflectplural(/s$/i, 's') inflectplural(/(ax|test)is$/i, '\1es') inflectplural(/(octop|vir)us$/i, '\1i') inflectplural(/(alias|status)$/i, '\1es') inflectplural(/(bu)s$/i, '\1ses') inflectplural(/(buffal|tomat)o$/i, '\1oes') inflectplural(/([ti])um$/i, '\1a') inflectplural(/sis$/i, 'ses') inflectplural(/( :([^f])fe|([lr])f)$/i, '\1\2ves') inflectplural(/(hive)$/i, '\1s') inflectplural(/([^aeiouy]|qu)y$/i, '\1ies') inflectplural(/(x|ch|ss|sh)$/i, '\1es') inflectplural(/(matr|vert|ind)( :ix|ex)$/i, '\1ices') inflectplural(/([m|l])ouse$/i, '\1ice') inflectplural(/^(ox)$/i, '\1en') inflectplural(/(quiz)$/i, '\1zes') inflectsingular(/s$/i, '') inflectsingular(/(n)ews$/i, '\1ews') inflectsingular(/([ti])a$/i, '\1um') inflectsingular(/((a)naly|(b)a|(d)iagno|(p)arenthe|(p)rogno| (s)ynop|(t)he)ses$/i, '\1\2sis') inflectsingular(/(^analy)ses$/i, '\1sis') inflectsingular(/([^f])ves$/i, '\1fe') inflectsingular(/(hive)s$/i, '\1') inflectsingular(/(tive)s$/i, '\1') inflectsingular(/([lr])ves$/i, '\1f') inflectsingular(/([^aeiouy]|qu)ies$/i, '\1y') inflectsingular(/(s)eries$/i, '\1eries') inflectsingular(/(m)ovies$/i, '\1ovie') inflectsingular(/(x|ch|ss|sh)es$/i, '\1') inflectsingular(/([m|l])ice$/i, '\1ouse') inflectsingular(/(bus)es$/i, '\1') inflectsingular(/(o)es$/i, '\1') inflectsingular(/(shoe)s$/i, '\1') inflectsingular(/(cris|ax|test)es$/i, '\1is')

inflectsingular(/(octop|vir)i$/i, '\1us') inflectsingular(/(alias|status)es$/i, '\1') inflectsingular(/^(ox)en/i, '\1') inflectsingular(/(vert|ind)ices$/i, '\1ex') inflectsingular(/(matr)ices$/i, '\1ix') inflectsingular(/(quiz)zes$/i, '\1') inflectsingular(/(database)s$/i, '\1') inflectirregular('person', 'people') inflectirregular('man', 'men') inflectirregular('child', 'children') inflectirregular('sex', 'sexes') inflectirregular('move', 'moves') inflectirregular('cow', 'kine')

A singleton instance of Inflections is yielded by Inflectorinflections, which can then be used to specify additional inflection rules in an initializer

ActiveSupport::Inflectorinflections do |inflect| inflectplural /^(ox)$/i, '\1en' inflectsingular /^(ox)en/i, '\1' inflectirregular 'octopus', 'octopi' inflectuncountable "equipment" end

New rules are added at the top So in the example, the irregular rule for octopus will now be the first of the pluralization and singularization rules that are checked when an inflection happens That way Rails can guarantee that your rules run before any of the rules that may already have been loaded

This API reference lists the inflections methods themselves in the modules where they are actually used: Numeric and String The Inflections module contains methods used for modifying the rules used by the inflector

clear(scope = :all))

Clears the loaded inflections within a given scope Give the scope as a symbol of the inflection type: :plurals, :singulars, :uncountables, or :humans

ActiveSupport::Inflectorinflectionsclear ActiveSupport::Inflectorinflectionsclear(:plurals)

human(rule, replacement)

Specifies a humanized form of a string by a regular expression rule or by a string mapping When using a regular expression based replacement, the normal humanize formatting is called after the replacement When a string is used, the human form should be specified as desired (example: The name , not the name )

ActiveSupport::Inflectorinflections do |inflect| inflecthuman /_cnt$/i, '\1_count' inflecthuman "legacy_col_person_name", "Name" end

Yields a singleton instance of ActiveSupport::Inflector::Inflections so you can specify additional inflector rules

irregular(singular, plural)

Specifies a new irregular that applies to both pluralization and singularization at the same time The singular and plural arguments must be strings, not regular expressions Simply pass the irregular word in singular and plural form

ActiveSupport::Inflectorinflections do |inflect| inflectirregular 'octopus', 'octopi' inflectirregular 'person', 'people' end

plural(rule, replacement)

Specifies a new pluralization rule and its replacement The rule can either be a string or a regular expression The replacement should always be a string and may include references to the matched data from the rule by using backslash-number syntax, like this: