class ActionController::Parameters

Action Controller Parameters

Allows to choose which attributes should be whitelisted for mass updating and thus prevent accidentally exposing that which shouldn't be exposed. Provides two methods for this purpose: require and permit. The former is used to mark parameters as required. The latter is used to set the parameter as permitted and limit which attributes should be allowed for mass updating.

params = ActionController::Parameters.new({
  person: {
    name: 'Francesco',
    age:  22,
    role: 'admin'
  }
})

permitted = params.require(:person).permit(:name, :age)
permitted            # => {"name"=>"Francesco", "age"=>22}
permitted.class      # => ActionController::Parameters
permitted.permitted? # => true

Person.first.update!(permitted)
# => #<Person id: 1, name: "Francesco", age: 22, role: "user">

It provides two options that controls the top-level behavior of new instances:

Examples:

params = ActionController::Parameters.new
params.permitted? # => false

ActionController::Parameters.permit_all_parameters = true

params = ActionController::Parameters.new
params.permitted? # => true

params = ActionController::Parameters.new(a: "123", b: "456")
params.permit(:c)
# => {}

ActionController::Parameters.action_on_unpermitted_parameters = :raise

params = ActionController::Parameters.new(a: "123", b: "456")
params.permit(:c)
# => ActionController::UnpermittedParameters: found unpermitted keys: a, b

Please note that these options *are not thread-safe*. In a multi-threaded environment they should only be set once at boot-time and never mutated at runtime.

ActionController::Parameters inherits from ActiveSupport::HashWithIndifferentAccess, this means that you can fetch values using either :key or "key".

params = ActionController::Parameters.new(key: 'value')
params[:key]  # => "value"
params["key"] # => "value"

Constants

EMPTY_ARRAY
PERMITTED_SCALAR_TYPES

This is a white list of permitted scalar types that includes the ones supported in XML and JSON requests.

This list is in particular used to filter ordinary requests, String goes as first element to quickly short-circuit the common case.

If you modify this collection please update the API of permit above.

Public Class Methods

const_missing(const_name) click to toggle source
Calls superclass method
# File lib/action_controller/metal/strong_parameters.rb, line 120
    def self.const_missing(const_name)
      super unless const_name == :NEVER_UNPERMITTED_PARAMS
      ActiveSupport::Deprecation.warn("        `ActionController::Parameters::NEVER_UNPERMITTED_PARAMS` has been deprecated.
        Use `ActionController::Parameters.always_permitted_parameters` instead.
".squish)

      always_permitted_parameters
    end
new(attributes = nil) click to toggle source

Returns a new instance of ActionController::Parameters. Also, sets the permitted attribute to the default value of ActionController::Parameters.permit_all_parameters.

class Person < ActiveRecord::Base
end

params = ActionController::Parameters.new(name: 'Francesco')
params.permitted?  # => false
Person.new(params) # => ActiveModel::ForbiddenAttributesError

ActionController::Parameters.permit_all_parameters = true

params = ActionController::Parameters.new(name: 'Francesco')
params.permitted?  # => true
Person.new(params) # => #<Person id: nil, name: "Francesco">
Calls superclass method
# File lib/action_controller/metal/strong_parameters.rb, line 146
def initialize(attributes = nil)
  super(attributes)
  @permitted = self.class.permit_all_parameters
end

Public Instance Methods

[](key) click to toggle source

Returns a parameter for the given key. If not found, returns nil.

params = ActionController::Parameters.new(person: { name: 'Francesco' })
params[:person] # => {"name"=>"Francesco"}
params[:none]   # => nil
Calls superclass method
# File lib/action_controller/metal/strong_parameters.rb, line 348
def [](key)
  convert_hashes_to_parameters(key, super)
end
converted_arrays() click to toggle source

Attribute that keeps track of converted arrays, if any, to avoid double looping in the common use case permit + mass-assignment. Defined in a method to instantiate it only if needed.

Testing membership still loops, but it's going to be faster than our own loop that converts values. Also, we are not going to build a new array object per fetch.

# File lib/action_controller/metal/strong_parameters.rb, line 195
def converted_arrays
  @converted_arrays ||= Set.new
end
delete(key, &block) click to toggle source

Deletes and returns a key-value pair from Parameters whose key is equal to key. If the key is not found, returns the default value. If the optional code block is given and the key is not found, pass in the key and return the result of block.

Calls superclass method
# File lib/action_controller/metal/strong_parameters.rb, line 418
def delete(key, &block)
  convert_hashes_to_parameters(key, super, false)
end
dup() click to toggle source

Returns an exact copy of the ActionController::Parameters instance. permitted state is kept on the duped object.

params = ActionController::Parameters.new(a: 1)
params.permit!
params.permitted?        # => true
copy_params = params.dup # => {"a"=>1}
copy_params.permitted?   # => true
Calls superclass method
# File lib/action_controller/metal/strong_parameters.rb, line 435
def dup
  super.tap do |duplicate|
    duplicate.permitted = @permitted
  end
end
each(&block)
Alias for: each_pair
each_pair(&block) click to toggle source

Convert all hashes in values into parameters, then yield each pair like the same way as Hash#each_pair

Calls superclass method
# File lib/action_controller/metal/strong_parameters.rb, line 178
def each_pair(&block)
  super do |key, value|
    convert_hashes_to_parameters(key, value)
  end

  super
end
Also aliased as: each
extract!(*keys) click to toggle source

Removes and returns the key/value pairs matching the given keys.

params = ActionController::Parameters.new(a: 1, b: 2, c: 3)
params.extract!(:a, :b) # => {"a"=>1, "b"=>2}
params                  # => {"c"=>3}
Calls superclass method
# File lib/action_controller/metal/strong_parameters.rb, line 385
def extract!(*keys)
  new_instance_with_inherited_permitted_status(super)
end
fetch(key, *args) click to toggle source

Returns a parameter for the given key. If the key can't be found, there are several options: With no other arguments, it will raise an ActionController::ParameterMissing error; if more arguments are given, then that will be returned; if a block is given, then that will be run and its result returned.

params = ActionController::Parameters.new(person: { name: 'Francesco' })
params.fetch(:person)               # => {"name"=>"Francesco"}
params.fetch(:none)                 # => ActionController::ParameterMissing: param not found: none
params.fetch(:none, 'Francesco')    # => "Francesco"
params.fetch(:none) { 'Francesco' } # => "Francesco"
Calls superclass method
# File lib/action_controller/metal/strong_parameters.rb, line 363
def fetch(key, *args)
  convert_hashes_to_parameters(key, super, false)
rescue KeyError
  raise ActionController::ParameterMissing.new(key)
end
permit(*filters) click to toggle source

Returns a new ActionController::Parameters instance that includes only the given filters and sets the permitted attribute for the object to true. This is useful for limiting which attributes should be allowed for mass updating.

params = ActionController::Parameters.new(user: { name: 'Francesco', age: 22, role: 'admin' })
permitted = params.require(:user).permit(:name, :age)
permitted.permitted?      # => true
permitted.has_key?(:name) # => true
permitted.has_key?(:age)  # => true
permitted.has_key?(:role) # => false

Only permitted scalars pass the filter. For example, given

params.permit(:name)

:name passes it is a key of params whose associated value is of type String, Symbol, NilClass, Numeric, TrueClass, FalseClass, Date, Time, DateTime, StringIO, IO, ActionDispatch::Http::UploadedFile or Rack::Test::UploadedFile. Otherwise, the key :name is filtered out.

You may declare that the parameter should be an array of permitted scalars by mapping it to an empty array:

params = ActionController::Parameters.new(tags: ['rails', 'parameters'])
params.permit(tags: [])

You can also use permit on nested parameters, like:

params = ActionController::Parameters.new({
  person: {
    name: 'Francesco',
    age:  22,
    pets: [{
      name: 'Purplish',
      category: 'dogs'
    }]
  }
})

permitted = params.permit(person: [ :name, { pets: :name } ])
permitted.permitted?                    # => true
permitted[:person][:name]               # => "Francesco"
permitted[:person][:age]                # => nil
permitted[:person][:pets][0][:name]     # => "Purplish"
permitted[:person][:pets][0][:category] # => nil

Note that if you use permit in a key that points to a hash, it won't allow all the hash. You also need to specify which attributes inside the hash should be whitelisted.

params = ActionController::Parameters.new({
  person: {
    contact: {
      email: 'none@test.com',
      phone: '555-1234'
    }
  }
})

params.require(:person).permit(:contact)
# => {}

params.require(:person).permit(contact: :phone)
# => {"contact"=>{"phone"=>"555-1234"}}

params.require(:person).permit(contact: [ :email, :phone ])
# => {"contact"=>{"email"=>"none@test.com", "phone"=>"555-1234"}}
# File lib/action_controller/metal/strong_parameters.rb, line 325
def permit(*filters)
  params = self.class.new

  filters.flatten.each do |filter|
    case filter
    when Symbol, String
      permitted_scalar_filter(params, filter)
    when Hash then
      hash_filter(params, filter)
    end
  end

  unpermitted_parameters!(params) if self.class.action_on_unpermitted_parameters

  params.permit!
end
permit!() click to toggle source

Sets the permitted attribute to true. This can be used to pass mass assignment. Returns self.

class Person < ActiveRecord::Base
end

params = ActionController::Parameters.new(name: 'Francesco')
params.permitted?  # => false
Person.new(params) # => ActiveModel::ForbiddenAttributesError
params.permit!
params.permitted?  # => true
Person.new(params) # => #<Person id: nil, name: "Francesco">
# File lib/action_controller/metal/strong_parameters.rb, line 221
def permit!
  each_pair do |key, value|
    Array.wrap(value).each do |v|
      v.permit! if v.respond_to? :permit!
    end
  end

  @permitted = true
  self
end
permitted?() click to toggle source

Returns true if the parameter is permitted, false otherwise.

params = ActionController::Parameters.new
params.permitted? # => false
params.permit!
params.permitted? # => true
# File lib/action_controller/metal/strong_parameters.rb, line 205
def permitted?
  @permitted
end
require(key) click to toggle source

Ensures that a parameter is present. If it's present, returns the parameter at the given key, otherwise raises an ActionController::ParameterMissing error.

ActionController::Parameters.new(person: { name: 'Francesco' }).require(:person)
# => {"name"=>"Francesco"}

ActionController::Parameters.new(person: nil).require(:person)
# => ActionController::ParameterMissing: param not found: person

ActionController::Parameters.new(person: {}).require(:person)
# => ActionController::ParameterMissing: param not found: person
# File lib/action_controller/metal/strong_parameters.rb, line 244
def require(key)
  value = self[key]
  if value.present? || value == false
    value
  else
    raise ParameterMissing.new(key)
  end
end
Also aliased as: required
required(key)

Alias of require.

Alias for: require
select!(&block) click to toggle source

Equivalent to Hash#keep_if, but returns nil if no changes were made.

Calls superclass method
# File lib/action_controller/metal/strong_parameters.rb, line 423
def select!(&block)
  convert_value_to_parameters(super)
end
slice(*keys) click to toggle source

Returns a new ActionController::Parameters instance that includes only the given keys. If the given keys don't exist, returns an empty hash.

params = ActionController::Parameters.new(a: 1, b: 2, c: 3)
params.slice(:a, :b) # => {"a"=>1, "b"=>2}
params.slice(:d)     # => {}
Calls superclass method
# File lib/action_controller/metal/strong_parameters.rb, line 376
def slice(*keys)
  new_instance_with_inherited_permitted_status(super)
end
to_h() click to toggle source

Returns a safe Hash representation of this parameter with all unpermitted keys removed.

params = ActionController::Parameters.new({
  name: 'Senjougahara Hitagi',
  oddity: 'Heavy stone crab'
})
params.to_h # => {}

safe_params = params.permit(:name)
safe_params.to_h # => {"name"=>"Senjougahara Hitagi"}
# File lib/action_controller/metal/strong_parameters.rb, line 162
def to_h
  if permitted?
    to_hash
  else
    slice(*self.class.always_permitted_parameters).permit!.to_h
  end
end
to_unsafe_h() click to toggle source

Returns an unsafe, unfiltered Hash representation of this parameter.

# File lib/action_controller/metal/strong_parameters.rb, line 171
def to_unsafe_h
  to_hash
end
Also aliased as: to_unsafe_hash
to_unsafe_hash()
Alias for: to_unsafe_h
transform_values() click to toggle source

Returns a new ActionController::Parameters with the results of running block once for every value. The keys are unchanged.

params = ActionController::Parameters.new(a: 1, b: 2, c: 3)
params.transform_values { |x| x * 2 }
# => {"a"=>2, "b"=>4, "c"=>6}
Calls superclass method
# File lib/action_controller/metal/strong_parameters.rb, line 395
def transform_values
  if block_given?
    new_instance_with_inherited_permitted_status(super)
  else
    super
  end
end

Protected Instance Methods

permitted=(new_permitted) click to toggle source
# File lib/action_controller/metal/strong_parameters.rb, line 442
def permitted=(new_permitted)
  @permitted = new_permitted
end

Private Instance Methods

array_of_permitted_scalars?(value) click to toggle source
# File lib/action_controller/metal/strong_parameters.rb, line 547
def array_of_permitted_scalars?(value)
  if value.is_a?(Array)
    value.all? {|element| permitted_scalar?(element)}
  end
end
array_of_permitted_scalars_filter(params, key) click to toggle source
# File lib/action_controller/metal/strong_parameters.rb, line 553
def array_of_permitted_scalars_filter(params, key)
  if has_key?(key) && array_of_permitted_scalars?(self[key])
    params[key] = self[key]
  end
end
convert_hashes_to_parameters(key, value, assign_if_converted=true) click to toggle source
# File lib/action_controller/metal/strong_parameters.rb, line 453
def convert_hashes_to_parameters(key, value, assign_if_converted=true)
  converted = convert_value_to_parameters(value)
  self[key] = converted if assign_if_converted && !converted.equal?(value)
  converted
end
convert_value_to_parameters(value) click to toggle source
# File lib/action_controller/metal/strong_parameters.rb, line 459
def convert_value_to_parameters(value)
  if value.is_a?(Array) && !converted_arrays.member?(value)
    converted = value.map { |_| convert_value_to_parameters(_) }
    converted_arrays << converted
    converted
  elsif value.is_a?(Parameters) || !value.is_a?(Hash)
    value
  else
    self.class.new(value)
  end
end
each_element(object) { |el| ... } click to toggle source
# File lib/action_controller/metal/strong_parameters.rb, line 471
def each_element(object)
  if object.is_a?(Array)
    object.map { |el| yield el }.compact
  elsif fields_for_style?(object)
    hash = object.class.new
    object.each { |k,v| hash[k] = yield v }
    hash
  else
    yield object
  end
end
fields_for_style?(object) click to toggle source
# File lib/action_controller/metal/strong_parameters.rb, line 483
def fields_for_style?(object)
  object.is_a?(Hash) && object.all? { |k, v| k =~ /\A-?\d+\z/ && v.is_a?(Hash) }
end
hash_filter(params, filter) click to toggle source
# File lib/action_controller/metal/strong_parameters.rb, line 560
def hash_filter(params, filter)
  filter = filter.with_indifferent_access

  # Slicing filters out non-declared keys.
  slice(*filter.keys).each do |key, value|
    next unless value

    if filter[key] == EMPTY_ARRAY
      # Declaration { comment_ids: [] }.
      array_of_permitted_scalars_filter(params, key)
    else
      # Declaration { user: :name } or { user: [:name, :age, { address: ... }] }.
      params[key] = each_element(value) do |element|
        if element.is_a?(Hash)
          element = self.class.new(element) unless element.respond_to?(:permit)
          element.permit(*Array.wrap(filter[key]))
        end
      end
    end
  end
end
new_instance_with_inherited_permitted_status(hash) click to toggle source
# File lib/action_controller/metal/strong_parameters.rb, line 447
def new_instance_with_inherited_permitted_status(hash)
  self.class.new(hash).tap do |new_instance|
    new_instance.permitted = @permitted
  end
end
permitted_scalar?(value) click to toggle source
# File lib/action_controller/metal/strong_parameters.rb, line 531
def permitted_scalar?(value)
  PERMITTED_SCALAR_TYPES.any? {|type| value.is_a?(type)}
end
permitted_scalar_filter(params, key) click to toggle source
# File lib/action_controller/metal/strong_parameters.rb, line 535
def permitted_scalar_filter(params, key)
  if has_key?(key) && permitted_scalar?(self[key])
    params[key] = self[key]
  end

  keys.grep(/\A#{Regexp.escape(key)}\(\d+[if]?\)\z/) do |k|
    if permitted_scalar?(self[k])
      params[k] = self[k]
    end
  end
end
unpermitted_keys(params) click to toggle source
# File lib/action_controller/metal/strong_parameters.rb, line 500
def unpermitted_keys(params)
  self.keys - params.keys - self.always_permitted_parameters
end
unpermitted_parameters!(params) click to toggle source
# File lib/action_controller/metal/strong_parameters.rb, line 487
def unpermitted_parameters!(params)
  unpermitted_keys = unpermitted_keys(params)
  if unpermitted_keys.any?
    case self.class.action_on_unpermitted_parameters
    when :log
      name = "unpermitted_parameters.action_controller"
      ActiveSupport::Notifications.instrument(name, keys: unpermitted_keys)
    when :raise
      raise ActionController::UnpermittedParameters.new(unpermitted_keys)
    end
  end
end