# Hashie [![Join the chat at https://gitter.im/intridea/hashie](https://badges.gitter.im/Join%20Chat.svg)](https://gitter.im/intridea/hashie?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge) [![Gem Version](http://img.shields.io/gem/v/hashie.svg)](http://badge.fury.io/rb/hashie) [![Build Status](http://img.shields.io/travis/intridea/hashie.svg)](https://travis-ci.org/intridea/hashie) [![Dependency Status](https://gemnasium.com/intridea/hashie.svg)](https://gemnasium.com/intridea/hashie) [![Code Climate](https://codeclimate.com/github/intridea/hashie.svg)](https://codeclimate.com/github/intridea/hashie) [![Coverage Status](https://codeclimate.com/github/intridea/hashie/badges/coverage.svg)](https://codeclimate.com/github/intridea/hashie) Hashie is a growing collection of tools that extend Hashes and make them more useful. ## Installation Hashie is available as a RubyGem: ```bash $ gem install hashie ``` ## Upgrading You're reading the documentation for the stable release of Hashie, 3.4.6. Please read [UPGRADING](UPGRADING.md) when upgrading from a previous version. ## Hash Extensions The library is broken up into a number of atomically includable Hash extension modules as described below. This provides maximum flexibility for users to mix and match functionality while maintaining feature parity with earlier versions of Hashie. Any of the extensions listed below can be mixed into a class by `include`-ing `Hashie::Extensions::ExtensionName`. ### Coercion Coercions allow you to set up "coercion rules" based either on the key or the value type to massage data as it's being inserted into the Hash. Key coercions might be used, for example, in lightweight data modeling applications such as an API client: ```ruby class Tweet < Hash include Hashie::Extensions::Coercion coerce_key :user, User end user_hash = { name: "Bob" } Tweet.new(user: user_hash) # => automatically calls User.coerce(user_hash) or # User.new(user_hash) if that isn't present. ``` Value coercions, on the other hand, will coerce values based on the type of the value being inserted. This is useful if you are trying to build a Hash-like class that is self-propagating. ```ruby class SpecialHash < Hash include Hashie::Extensions::Coercion coerce_value Hash, SpecialHash def initialize(hash = {}) super hash.each_pair do |k,v| self[k] = v end end end ``` ### Coercing Collections ```ruby class Tweet < Hash include Hashie::Extensions::Coercion coerce_key :mentions, Array[User] coerce_key :friends, Set[User] end user_hash = { name: "Bob" } mentions_hash= [user_hash, user_hash] friends_hash = [user_hash] tweet = Tweet.new(mentions: mentions_hash, friends: friends_hash) # => automatically calls User.coerce(user_hash) or # User.new(user_hash) if that isn't present on each element of the array tweet.mentions.map(&:class) # => [User, User] tweet.friends.class # => Set ``` ### Coercing Hashes ```ruby class Relation def initialize(string) @relation = string end end class Tweet < Hash include Hashie::Extensions::Coercion coerce_key :relations, Hash[User => Relation] end user_hash = { name: "Bob" } relations_hash= { user_hash => "father", user_hash => "friend" } tweet = Tweet.new(relations: relations_hash) tweet.relations.map { |k,v| [k.class, v.class] } # => [[User, Relation], [User, Relation]] tweet.relations.class # => Hash # => automatically calls User.coerce(user_hash) on each key # and Relation.new on each value since Relation doesn't define the `coerce` class method ``` ### Coercing Core Types Hashie handles coercion to the following by using standard conversion methods: | type | method | |----------|----------| | Integer | `#to_i` | | Float | `#to_f` | | Complex | `#to_c` | | Rational | `#to_r` | | String | `#to_s` | | Symbol | `#to_sym`| **Note**: The standard Ruby conversion methods are less strict than you may assume. For example, `:foo.to_i` raises an error but `"foo".to_i` returns 0. You can also use coerce from the following supertypes with `coerce_value`: - Integer - Numeric Hashie does not have built-in support for coercion boolean values, since Ruby does not have a built-in boolean type or standard method for to a boolean. You can coerce to booleans using a custom proc. ### Coercion Proc You can use a custom coercion proc on either `#coerce_key` or `#coerce_value`. This is useful for coercing to booleans or other simple types without creating a new class and `coerce` method. For example: ```ruby class Tweet < Hash include Hashie::Extensions::Coercion coerce_key :retweeted, ->(v) do case v when String !!(v =~ /\A(true|t|yes|y|1)\z/i) when Numeric !v.to_i.zero? else v == true end end end ``` #### A note on circular coercion Since `coerce_key` is a class-level method, you cannot have circular coercion without the use of a proc. For example: ```ruby class CategoryHash < Hash include Hashie::Extensions::Coercion include Hashie::Extensions::MergeInitializer coerce_key :products, Array[ProductHash] end class ProductHash < Hash include Hashie::Extensions::Coercion include Hashie::Extensions::MergeInitializer coerce_key :categories, Array[CategoriesHash] end ``` This will fail with a `NameError` for `CategoryHash::ProductHash` because `ProductHash` is not defined at the point that `coerce_key` is happening for `CategoryHash`. To work around this, you can use a coercion proc. For example, you could do: ```ruby class CategoryHash < Hash # ... coerce_key :products, ->(value) do return value.map { |v| ProductHash.new(v) } if value.respond_to?(:map) ProductHash.new(value) end end ``` ### KeyConversion The KeyConversion extension gives you the convenience methods of `symbolize_keys` and `stringify_keys` along with their bang counterparts. You can also include just stringify or just symbolize with `Hashie::Extensions::StringifyKeys` or `Hashie::Extensions::SymbolizeKeys`. Hashie also has a utility method for converting keys on a Hash without a mixin: ```ruby Hashie.symbolize_keys! hash # => Symbolizes keys of hash. Hashie.symbolize_keys hash # => Returns a copy of hash with keys symbolized. Hashie.stringify_keys! hash # => Stringifies keys of hash. Hashie.stringify_keys hash # => Returns a copy of hash with keys stringified. ``` ### MergeInitializer The MergeInitializer extension simply makes it possible to initialize a Hash subclass with another Hash, giving you a quick short-hand. ### MethodAccess The MethodAccess extension allows you to quickly build method-based reading, writing, and querying into your Hash descendant. It can also be included as individual modules, i.e. `Hashie::Extensions::MethodReader`, `Hashie::Extensions::MethodWriter` and `Hashie::Extensions::MethodQuery`. ```ruby class MyHash < Hash include Hashie::Extensions::MethodAccess end h = MyHash.new h.abc = 'def' h.abc # => 'def' h.abc? # => true ``` ### MethodAccessWithOverride The MethodAccessWithOverride extension is like the MethodAccess extension, except that it allows you to override Hash methods. It aliases any overridden method with two leading underscores. To include only this overriding functionality, you can include the single module `Hashie::Extensions::MethodOverridingWriter`. ```ruby class MyHash < Hash include Hashie::Extensions::MethodAccess end class MyOverridingHash < Hash include Hashie::Extensions::MethodAccessWithOverride end non_overriding = MyHash.new non_overriding.zip = 'a-dee-doo-dah' non_overriding.zip #=> [[['zip', 'a-dee-doo-dah']]] overriding = MyOverridingHash.new overriding.zip = 'a-dee-doo-dah' overriding.zip #=> 'a-dee-doo-dah' overriding.__zip #=> [[['zip', 'a-dee-doo-dah']]] ``` ### IndifferentAccess This extension can be mixed in to your Hash subclass to allow you to use Strings or Symbols interchangeably as keys; similar to the `params` hash in Rails. In addition, IndifferentAccess will also inject itself into sub-hashes so they behave the same. Example: ```ruby class MyHash < Hash include Hashie::Extensions::MergeInitializer include Hashie::Extensions::IndifferentAccess end myhash = MyHash.new(:cat => 'meow', 'dog' => 'woof') myhash['cat'] # => "meow" myhash[:cat] # => "meow" myhash[:dog] # => "woof" myhash['dog'] # => "woof" # Auto-Injecting into sub-hashes. myhash['fishes'] = {} myhash['fishes'].class # => Hash myhash['fishes'][:food] = 'flakes' myhash['fishes']['food'] # => "flakes" ``` ### IgnoreUndeclared This extension can be mixed in to silently ignore undeclared properties on initialization instead of raising an error. This is useful when using a Trash to capture a subset of a larger hash. ```ruby class Person < Trash include Hashie::Extensions::IgnoreUndeclared property :first_name property :last_name end user_data = { first_name: 'Freddy', last_name: 'Nostrils', email: 'freddy@example.com' } p = Person.new(user_data) # 'email' is silently ignored p.first_name # => 'Freddy' p.last_name # => 'Nostrils' p.email # => NoMethodError ``` ### DeepMerge This extension allow you to easily include a recursive merging system to any Hash descendant: ```ruby class MyHash < Hash include Hashie::Extensions::DeepMerge end h1 = MyHash[{ x: { y: [4,5,6] }, z: [7,8,9] }] h2 = MyHash[{ x: { y: [7,8,9] }, z: "xyz" }] h1.deep_merge(h2) # => { x: { y: [7, 8, 9] }, z: "xyz" } h2.deep_merge(h1) # => { x: { y: [4, 5, 6] }, z: [7, 8, 9] } ``` Like with Hash#merge in the standard library, a block can be provided to merge values: ```ruby class MyHash < Hash include Hashie::Extensions::DeepMerge end h1 = MyHash[{ a: 100, b: 200, c: { c1: 100 } }] h2 = MyHash[{ b: 250, c: { c1: 200 } }] h1.deep_merge(h2) { |key, this_val, other_val| this_val + other_val } # => { a: 100, b: 450, c: { c1: 300 } } ``` ### DeepFetch This extension can be mixed in to provide for safe and concise retrieval of deeply nested hash values. In the event that the requested key does not exist a block can be provided and its value will be returned. Though this is a hash extension, it conveniently allows for arrays to be present in the nested structure. This feature makes the extension particularly useful for working with JSON API responses. ```ruby user = { name: { first: 'Bob', last: 'Boberts' }, groups: [ { name: 'Rubyists' }, { name: 'Open source enthusiasts' } ] } user.extend Hashie::Extensions::DeepFetch user.deep_fetch :name, :first # => 'Bob' user.deep_fetch :name, :middle # => 'KeyError: Could not fetch middle' # using a default block user.deep_fetch(:name, :middle) { |key| 'default' } # => 'default' # a nested array user.deep_fetch :groups, 1, :name # => 'Open source enthusiasts' ``` ### DeepFind This extension can be mixed in to provide for concise searching for keys within a deeply nested hash. It can also search through any Enumerable contained within the hash for objects with the specified key. Note: The searches are depth-first, so it is not guaranteed that a shallowly nested value will be found before a deeply nested value. ```ruby user = { name: { first: 'Bob', last: 'Boberts' }, groups: [ { name: 'Rubyists' }, { name: 'Open source enthusiasts' } ] } user.extend Hashie::Extensions::DeepFind user.deep_find(:name) #=> { first: 'Bob', last: 'Boberts' } user.deep_detect(:name) #=> { first: 'Bob', last: 'Boberts' } user.deep_find_all(:name) #=> [{ first: 'Bob', last: 'Boberts' }, 'Rubyists', 'Open source enthusiasts'] user.deep_select(:name) #=> [{ first: 'Bob', last: 'Boberts' }, 'Rubyists', 'Open source enthusiasts'] ``` ### DeepLocate This extension can be mixed in to provide a depth first search based search for enumerables matching a given comparator callable. It returns all enumerables which contain at least one element, for which the given comparator returns ```true```. Because the container objects are returned, the result elements can be modified in place. This way, one can perform modifications on deeply nested hashes without the need to know the exact paths. ```ruby books = [ { title: "Ruby for beginners", pages: 120 }, { title: "CSS for intermediates", pages: 80 }, { title: "Collection of ruby books", books: [ { title: "Ruby for the rest of us", pages: 576 } ] } ] books.extend(Hashie::Extensions::DeepLocate) # for ruby 1.9 leave *no* space between the lambda rocket and the braces # http://ruby-journal.com/becareful-with-space-in-lambda-hash-rocket-syntax-between-ruby-1-dot-9-and-2-dot-0/ books.deep_locate -> (key, value, object) { key == :title && value.include?("Ruby") } # => [{:title=>"Ruby for beginners", :pages=>120}, {:title=>"Ruby for the rest of us", :pages=>576}] books.deep_locate -> (key, value, object) { key == :pages && value <= 120 } # => [{:title=>"Ruby for beginners", :pages=>120}, {:title=>"CSS for intermediates", :pages=>80}] ``` ## StrictKeyAccess This extension can be mixed in to allow a Hash to raise an error when attempting to extract a value using a non-existent key. ### Example: ```ruby class StrictKeyAccessHash < Hash include Hashie::Extensions::StrictKeyAccess end >> hash = StrictKeyAccessHash[foo: "bar"] => {:foo=>"bar"} >> hash[:foo] => "bar" >> hash[:cow] KeyError: key not found: :cow ``` ## Mash Mash is an extended Hash that gives simple pseudo-object functionality that can be built from hashes and easily extended. It is intended to give the user easier access to the objects within the Mash through a property-like syntax, while still retaining all Hash functionality. ### Example: ```ruby mash = Hashie::Mash.new mash.name? # => false mash.name # => nil mash.name = "My Mash" mash.name # => "My Mash" mash.name? # => true mash.inspect # => mash = Hashie::Mash.new # use bang methods for multi-level assignment mash.author!.name = "Michael Bleigh" mash.author # => mash = Hashie::Mash.new # use under-bang methods for multi-level testing mash.author_.name? # => false mash.inspect # => ``` **Note:** The `?` method will return false if a key has been set to false or nil. In order to check if a key has been set at all, use the `mash.key?('some_key')` method instead. Please note that a Mash will not override methods through the use of the property-like syntax. This can lead to confusion if you expect to be able to access a Mash value through the property-like syntax for a key that conflicts with a method name. However, it protects users of your library from the unexpected behavior of those methods being overridden behind the scenes. ### Example: ```ruby mash = Hashie::Mash.new mash.name = "My Mash" mash.zip = "Method Override?" mash.zip # => [[["name", "My Mash"]], [["zip", "Method Override?"]]] ``` Mash allows you also to transform any files into a Mash objects. ### Example: ```yml #/etc/config/settings/twitter.yml development: api_key: 'api_key' production: api_key: <%= ENV['API_KEY'] %> #let's say that ENV['API_KEY'] is set to 'abcd' ``` ```ruby mash = Mash.load('settings/twitter.yml') mash.development.api_key # => 'localhost' mash.development.api_key = "foo" # => <# RuntimeError can't modify frozen ...> mash.development.api_key? # => true ``` You can also load with a `Pathname` object: ```ruby mash = Mash.load(Pathname 'settings/twitter.yml') mash.development.api_key # => 'localhost' ``` You can access a Mash from another class: ```ruby mash = Mash.load('settings/twitter.yml')[ENV['RACK_ENV']] Twitter.extend mash.to_module # NOTE: if you want another name than settings, call: to_module('my_settings') Twitter.settings.api_key # => 'abcd' ``` You can use another parser (by default: YamlErbParser): ``` #/etc/data/user.csv id | name | lastname ---|------------- | ------------- 1 |John | Doe 2 |Laurent | Garnier ``` ```ruby mash = Mash.load('data/user.csv', parser: MyCustomCsvParser) # => { 1 => { name: 'John', lastname: 'Doe'}, 2 => { name: 'Laurent', lastname: 'Garnier' } } mash[1] #=> { name: 'John', lastname: 'Doe' } ``` ### Mash Extension: SafeAssignment This extension can be mixed into a Mash to guard the attempted overwriting of methods by property setters. When mixed in, the Mash will raise an `ArgumentError` if you attempt to write a property with the same name as an existing method. #### Example: ```ruby class SafeMash < ::Hashie::Mash include Hashie::Extensions::Mash::SafeAssignment end safe_mash = SafeMash.new safe_mash.zip = 'Test' # => ArgumentError safe_mash[:zip] = 'test' # => still ArgumentError ``` ## Dash Dash is an extended Hash that has a discrete set of defined properties and only those properties may be set on the hash. Additionally, you can set defaults for each property. You can also flag a property as required. Required properties will raise an exception if unset. Another option is message for required properties, which allow you to add custom messages for required property. You can also conditionally require certain properties by passing a Proc or Symbol. If a Proc is provided, it will be run in the context of the Dash instance. If a Symbol is provided, the value returned for the property or method of the same name will be evaluated. The property will be required if the result of the conditional is truthy. ### Example: ```ruby class Person < Hashie::Dash property :name, required: true property :age, required: true, message: 'must be set.' property :email property :phone, required: -> { email.nil? }, message: 'is required if email is not set.' property :pants, required: :weekday?, message: 'are only required on weekdays.' property :occupation, default: 'Rubyist' def weekday? [ Time.now.saturday?, Time.now.sunday? ].none? end end p = Person.new # => ArgumentError: The property 'name' is required for this Dash. p = Person.new(name: 'Bob') # => ArgumentError: The property 'age' must be set. p = Person.new(name: "Bob", age: 18) p.name # => 'Bob' p.name = nil # => ArgumentError: The property 'name' is required for this Dash. p.age # => 18 p.age = nil # => ArgumentError: The property 'age' must be set. p.email = 'abc@def.com' p.occupation # => 'Rubyist' p.email # => 'abc@def.com' p[:awesome] # => NoMethodError p[:occupation] # => 'Rubyist' p.update_attributes!(name: 'Trudy', occupation: 'Evil') p.occupation # => 'Evil' p.name # => 'Trudy' p.update_attributes!(occupation: nil) p.occupation # => 'Rubyist' ``` Properties defined as symbols are not the same thing as properties defined as strings. ### Example: ```ruby class Tricky < Hashie::Dash property :trick property 'trick' end p = Tricky.new(trick: 'one', 'trick' => 'two') p.trick # => 'one', always symbol version p[:trick] # => 'one' p['trick'] # => 'two' ``` Note that accessing a property as a method always uses the symbol version. ```ruby class Tricky < Hashie::Dash property 'trick' end p = Tricky.new('trick' => 'two') p.trick # => NoMethodError ``` ### Dash Extension: PropertyTranslation The `Hashie::Extensions::Dash::PropertyTranslation` mixin extends a Dash with the ability to remap keys from a source hash. ### Example from inconsistent APIs Property translation is useful when you need to read data from another application -- such as a Java API -- where the keys are named differently from Ruby conventions. ```ruby class PersonHash < Hashie::Dash include Hashie::Extensions::Dash::PropertyTranslation property :first_name, from: :firstName property :last_name, from: :lastName property :first_name, from: :f_name property :last_name, from: :l_name end person = PersonHash.new(firstName: 'Michael', l_name: 'Bleigh') person[:first_name] #=> 'Michael' person[:last_name] #=> 'Bleigh ``` ### Example using translation lambdas You can also use a lambda to translate the value. This is particularly useful when you want to ensure the type of data you're wrapping. ```ruby class DataModelHash < Hashie::Dash include Hashie::Extensions::Dash::PropertyTranslation property :id, transform_with: ->(value) { value.to_i } property :created_at, from: :created, with: ->(value) { Time.parse(value) } end model = DataModelHash.new(id: '123', created: '2014-04-25 22:35:28') model.id.class #=> Fixnum model.created_at.class #=> Time ``` ### Mash and Rails 4 Strong Parameters To enable compatibility with Rails 4 use the [hashie-forbidden_attributes](https://github.com/Maxim-Filimonov/hashie-forbidden_attributes) gem. ### Dash Extension: Coercion. If you want to use `Hashie::Extensions::Coercion` together with `Dash` then you may probably want to use `Hashie::Extensions::Dash::Coercion` instead. This extension automatically includes `Hashie::Extensions::Coercion` and also adds a convenient `:coerce` option to `property` so you can define coercion in one line instead of using `property` and `coerce_key` separate: ```ruby class UserHash < Hashie::Dash include Hashie::Extensions::Coercion property :id property :posts coerce_key :posts, Array[PostHash] end ``` This is the same as: ```ruby class UserHash < Hashie::Dash include Hashie::Extensions::Dash::Coercion property :id property :posts, coerce: Array[PostHash] end ``` ## Trash A Trash is a Dash that allows you to translate keys on initialization. It mixes in the PropertyTranslation mixin by default and is used like so: ```ruby class Person < Hashie::Trash property :first_name, from: :firstName end ``` This will automatically translate the firstName key to first_name when it is initialized using a hash such as through: ```ruby Person.new(firstName: 'Bob') ``` Trash also supports translations using lambda, this could be useful when dealing with external API's. You can use it in this way: ```ruby class Result < Hashie::Trash property :id, transform_with: lambda { |v| v.to_i } property :created_at, from: :creation_date, with: lambda { |v| Time.parse(v) } end ``` this will produce the following ```ruby result = Result.new(id: '123', creation_date: '2012-03-30 17:23:28') result.id.class # => Fixnum result.created_at.class # => Time ``` ## Clash Clash is a Chainable Lazy Hash that allows you to easily construct complex hashes using method notation chaining. This will allow you to use a more action-oriented approach to building options hashes. Essentially, a Clash is a generalized way to provide much of the same kind of "chainability" that libraries like Arel or Rails 2.x's named_scopes provide. ### Example: ```ruby c = Hashie::Clash.new c.where(abc: 'def').order(:created_at) c # => { where: { abc: 'def' }, order: :created_at } # You can also use bang notation to chain into sub-hashes, # jumping back up the chain with _end! c = Hashie::Clash.new c.where!.abc('def').ghi(123)._end!.order(:created_at) c # => { where: { abc: 'def', ghi: 123 }, order: :created_at } # Multiple hashes are merged automatically c = Hashie::Clash.new c.where(abc: 'def').where(hgi: 123) c # => { where: { abc: 'def', hgi: 123 } } ``` ## Rash Rash is a Hash whose keys can be Regexps or Ranges, which will map many input keys to a value. A good use case for the Rash is an URL router for a web framework, where URLs need to be mapped to actions; the Rash's keys match URL patterns, while the values call the action which handles the URL. If the Rash's value is a `proc`, the `proc` will be automatically called with the regexp's MatchData (matched groups) as a block argument. ### Example: ```ruby # Mapping names to appropriate greetings greeting = Hashie::Rash.new( /^Mr./ => "Hello sir!", /^Mrs./ => "Evening, madame." ) greeting["Mr. Steve Austin"] # => "Hello sir!" greeting["Mrs. Steve Austin"] # => "Evening, madame." # Mapping statements to saucy retorts mapper = Hashie::Rash.new( /I like (.+)/ => proc { |m| "Who DOESN'T like #{m[1]}?!" }, /Get off my (.+)!/ => proc { |m| "Forget your #{m[1]}, old man!" } ) mapper["I like traffic lights"] # => "Who DOESN'T like traffic lights?!" mapper["Get off my lawn!"] # => "Forget your lawn, old man!" ``` ### Auto-optimized **Note:** The Rash is automatically optimized every 500 accesses (which means that it sorts the list of Regexps, putting the most frequently matched ones at the beginning). If this value is too low or too high for your needs, you can tune it by setting: `rash.optimize_every = n`. ## Contributing See [CONTRIBUTING.md](CONTRIBUTING.md) ## Copyright Copyright (c) 2009-2014 Intridea, Inc. (http://intridea.com/) and [contributors](https://github.com/intridea/hashie/graphs/contributors). MIT License. See [LICENSE](LICENSE) for details.