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Class: ActionController::Parameters

Relationships & Source Files
Inherits: Object
Defined in: actionpack/lib/action_controller/metal/strong_parameters.rb

Overview

Allows you to choose which attributes should be permitted 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            # => #<ActionController::Parameters {"name"=>"Francesco", "age"=>22} permitted: true>
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:

  • .permit_all_parameters - If it’s true, all the parameters will be permitted by default. The default is false.

  • .action_on_unpermitted_parameters - Controls behavior when parameters that are not explicitly permitted are found. The default value is :log in test and development environments, false otherwise. The values can be:

    • false to take no action.

    • :log to emit an ActiveSupport::Notifications.instrument event on the unpermitted_parameters.action_controller topic and log at the DEBUG level.

    • :raise to raise an ActionController::UnpermittedParameters exception.

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 {} permitted: true>

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.

You can fetch values of Parameters using either :key or "key".

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

Constant Summary

Class Attribute Summary

Class Method Summary

Instance Attribute Summary

Instance Method Summary

Constructor Details

.new(parameters = {}, logging_context = {}) ⇒ Parameters

Returns a new Parameters instance. Also, sets the permitted attribute to the default value of .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">
[ GitHub ]

  
# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 269

def initialize(parameters = {}, logging_context = {})
  parameters.each_key do |key|
    unless key.is_a?(String) || key.is_a?(Symbol)
      raise InvalidParameterKey, "all keys must be Strings or Symbols, got: #{key.class}"
    end
  end

  @parameters = parameters.with_indifferent_access
  @logging_context = logging_context
  @permitted = self.class.permit_all_parameters
end

Class Attribute Details

.action_on_unpermitted_parameters (rw)

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# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 145

cattr_accessor :action_on_unpermitted_parameters, instance_accessor: false

.allow_deprecated_parameters_hash_equality (rw)

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# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 245

cattr_accessor :allow_deprecated_parameters_hash_equality, default: true, instance_accessor: false

.always_permitted_parameters (rw) Also known as: #always_permitted_parameters

By default, never raise an UnpermittedParameters exception if these params are present. The default includes both ‘controller’ and ‘action’ because they are added by ::Rails and should be of no concern. One way to change these is to specify always_permitted_parameters in your config. For instance:

config.action_controller.always_permitted_parameters = %w( controller action format )
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# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 243

cattr_accessor :always_permitted_parameters, default: %w( controller action )

.permit_all_parameters (rw)

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# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 143

cattr_accessor :permit_all_parameters, instance_accessor: false, default: false

Instance Attribute Details

#always_permitted_parameters (rw)

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# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 243

cattr_accessor :always_permitted_parameters, default: %w( controller action )

#each_key(&block) (readonly)

Calls block once for each key in the parameters, passing the key. If no block is given, an enumerator is returned instead.

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# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 229

delegate :keys, :empty?, :exclude?, :include?,
  :as_json, :to_s, :each_key, to: :@parameters

#has_key? (readonly)

Alias for #include?.

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# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 232

alias_method :has_key?, :include?

#key? (readonly)

Alias for #include?.

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# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 233

alias_method :key?, :include?

#keys (readonly)

Returns a new array of the keys of the parameters.

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# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 229

delegate :keys, :empty?, :exclude?, :include?,
  :as_json, :to_s, :each_key, to: :@parameters

#member? (readonly)

Alias for #include?.

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# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 234

alias_method :member?, :include?

#permitted?Boolean (rw)

Returns true if the parameter is permitted, false otherwise.

params = ActionController::Parameters.new
params.permitted? # => false
params.permit!
params.permitted? # => true
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# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 440

def permitted?
  @permitted
end

Instance Method Details

#==(other)

Returns true if another Parameters object contains the same content and permitted flag.

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# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 283

def ==(other)
  if other.respond_to?(:permitted?)
    permitted? == other.permitted? && parameters == other.parameters
  else
    if self.class.allow_deprecated_parameters_hash_equality && Hash === other
      ActionController.deprecator.warn <<-WARNING.squish
        Comparing equality between `ActionController::Parameters` and a
        `Hash` is deprecated and will be removed in Rails 7.2. Please only do
        comparisons between instances of `ActionController::Parameters`. If
        you need to compare to a hash, first convert it using
        `ActionController::Parameters#new`.
        To disable the deprecated behavior set
        `Rails.application.config.action_controller.allow_deprecated_parameters_hash_equality = false`.
      WARNING
      @parameters == other
    else
      super
    end
  end
end

#[](key)

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

params = ActionController::Parameters.new(person: { name: "Francesco" })
params[:person] # => #<ActionController::Parameters {"name"=>"Francesco"} permitted: false>
params[:none]   # => nil
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# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 665

def [](key)
  convert_hashes_to_parameters(key, @parameters[key])
end

#[]=(key, value)

Assigns a value to a given key. The given key may still get filtered out when #permit is called.

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# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 671

def []=(key, value)
  @parameters[key] = value
end

#as_json(options = nil)

Returns a hash that can be used as the JSON representation for the parameters.

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# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 229

delegate :keys, :empty?, :exclude?, :include?,
  :as_json, :to_s, :each_key, to: :@parameters

#compact

Returns a new Parameters instance with nil values removed.

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# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 842

def compact
  new_instance_with_inherited_permitted_status(@parameters.compact)
end

#compact!

Removes all nil values in place and returns self, or nil if no changes were made.

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# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 847

def compact!
  self if @parameters.compact!
end

#compact_blank

Returns a new Parameters instance without the blank values. Uses Object#blank? for determining if a value is blank.

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# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 853

def compact_blank
  reject { |_k, v| v.blank? }
end

#compact_blank!

Removes all blank values in place and returns self. Uses Object#blank? for determining if a value is blank.

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# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 859

def compact_blank!
  reject! { |_k, v| v.blank? }
end

#converted_arrays

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.

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# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 430

def converted_arrays
  @converted_arrays ||= Set.new
end

#deep_dup

Returns a duplicate Parameters instance with the same permitted parameters.

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# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 958

def deep_dup
  self.class.new(@parameters.deep_dup, @logging_context).tap do |duplicate|
    duplicate.permitted = @permitted
  end
end

#deep_merge(other_hash, &block)

Returns a new Parameters instance with self and other_hash merged recursively.

Like with Hash#merge in the standard library, a block can be provided to merge values.

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# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 148

rdoc_method :method: deep_merge

#deep_merge!(other_hash, &block)

Same as #deep_merge, but modifies self.

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# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 162

rdoc_method :method: deep_merge!

#deep_transform_keys(&block)

Returns a new Parameters instance with the results of running block once for every key. This includes the keys from the root hash and from all nested hashes and arrays. The values are unchanged.

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# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 793

def deep_transform_keys(&block)
  new_instance_with_inherited_permitted_status(
    _deep_transform_keys_in_object(@parameters, &block).to_unsafe_h
  )
end

#deep_transform_keys!(&block)

Returns the same Parameters instance with changed keys. This includes the keys from the root hash and from all nested hashes and arrays. The values are unchanged.

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# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 802

def deep_transform_keys!(&block)
  @parameters = _deep_transform_keys_in_object(@parameters, &block).to_unsafe_h
  self
end

#delete(key, &block)

Deletes a key-value pair from Parameters and returns the value. If key is not found, returns nil (or, with optional code block, yields key and returns the result). This method is similar to #extract!, which returns the corresponding Parameters object.

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# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 811

def delete(key, &block)
  convert_value_to_parameters(@parameters.delete(key, &block))
end

#delete_if(&block)

Alias for #reject!.

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# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 839

alias_method :delete_if, :reject!

#dig(*keys)

Extracts the nested parameter from the given #keys by calling dig at each step. Returns nil if any intermediate step is nil.

params = ActionController::Parameters.new(foo: { bar: { baz: 1 } })
params.dig(:foo, :bar, :baz) # => 1
params.dig(:foo, :zot, :xyz) # => nil

params2 = ActionController::Parameters.new(foo: [10, 11, 12])
params2.dig(:foo, 1) # => 11
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# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 709

def dig(*keys)
  convert_hashes_to_parameters(keys.first, @parameters[keys.first])
  @parameters.dig(*keys)
end

#each(&block)

Alias for #each_pair.

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# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 405

alias_method :each, :each_pair

#each_pair(&block) Also known as: #each

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

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# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 397

def each_pair(&block)
  return to_enum(__callee__) unless block_given?
  @parameters.each_pair do |key, value|
    yield [key, convert_hashes_to_parameters(key, value)]
  end

  self
end

#each_value(&block)

Convert all hashes in values into parameters, then yield each value in the same way as Hash#each_value.

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# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 409

def each_value(&block)
  return to_enum(:each_value) unless block_given?
  @parameters.each_pair do |key, value|
    yield convert_hashes_to_parameters(key, value)
  end

  self
end

#empty?Boolean

Returns true if the parameters have no key/value pairs.

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# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 229

delegate :keys, :empty?, :exclude?, :include?,
  :as_json, :to_s, :each_key, to: :@parameters

#eql?(other) ⇒ Boolean

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# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 304

def eql?(other)
  self.class == other.class &&
    permitted? == other.permitted? &&
    parameters.eql?(other.parameters)
end

#except(*keys) Also known as: #without

Returns a new Parameters instance that filters out the given #keys.

params = ActionController::Parameters.new(a: 1, b: 2, c: 3)
params.except(:a, :b) # => #<ActionController::Parameters {"c"=>3} permitted: false>
params.except(:d)     # => #<ActionController::Parameters {"a"=>1, "b"=>2, "c"=>3} permitted: false>
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# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 738

def except(*keys)
  new_instance_with_inherited_permitted_status(@parameters.except(*keys))
end

#exclude?(key) ⇒ Boolean

Returns true if the given key is not present in the parameters.

[ GitHub ]

  
# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 229

delegate :keys, :empty?, :exclude?, :include?,
  :as_json, :to_s, :each_key, to: :@parameters

#extract!(*keys)

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) # => #<ActionController::Parameters {"a"=>1, "b"=>2} permitted: false>
params                  # => #<ActionController::Parameters {"c"=>3} permitted: false>
[ GitHub ]

  
# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 748

def extract!(*keys)
  new_instance_with_inherited_permitted_status(@parameters.extract!(*keys))
end

#extract_value(key, delimiter: "_")

Returns parameter value for the given key separated by delimiter.

params = ActionController::Parameters.new(id: "1_123", tags: "ruby,rails")
params.extract_value(:id) # => ["1", "123"]
params.extract_value(:tags, delimiter: ",") # => ["ruby", "rails"]
params.extract_value(:non_existent_key) # => nil

Note that if the given key‘s value contains blank elements, then the returned array will include empty strings.

params = ActionController::Parameters.new(tags: "ruby,rails,,web")
params.extract_value(:tags, delimiter: ",") # => ["ruby", "rails", "", "web"]
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# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 976

def extract_value(key, delimiter: "_")
  @parameters[key]&.split(delimiter, -1)
end

#fetch(key, *args)

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 ParameterMissing error; if a second argument is given, then that is returned (converted to an instance of Parameters if possible); if a block is given, then that will be run and its result returned.

params = ActionController::Parameters.new(person: { name: "Francesco" })
params.fetch(:person)               # => #<ActionController::Parameters {"name"=>"Francesco"} permitted: false>
params.fetch(:none)                 # => ActionController::ParameterMissing: param is missing or the value is empty: none
params.fetch(:none, {})             # => #<ActionController::Parameters {} permitted: false>
params.fetch(:none, "Francesco")    # => "Francesco"
params.fetch(:none) { "Francesco" } # => "Francesco"
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# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 688

def fetch(key, *args)
  convert_value_to_parameters(
    @parameters.fetch(key) {
      if block_given?
        yield
      else
        args.fetch(0) { raise ActionController::ParameterMissing.new(key, @parameters.keys) }
      end
    }
  )
end

#has_value?(value) ⇒ Boolean Also known as: #value?

Returns true if the given value is present for some key in the parameters.

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# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 864

def has_value?(value)
  each_value.include?(convert_value_to_parameters(value))
end

#hash

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# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 310

def hash
  [self.class, @parameters, @permitted].hash
end

#include?(key) ⇒ Boolean Also known as: #has_key?, #key?, #member?

Returns true if the given key is present in the parameters.

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# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 229

delegate :keys, :empty?, :exclude?, :include?,
  :as_json, :to_s, :each_key, to: :@parameters

#inspect

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# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 922

def inspect
  "#<#{self.class} #{@parameters} permitted: #{@permitted}>"
end

#keep_if(&block)

Alias for #select!.

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# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 826

alias_method :keep_if, :select!

#merge(other_hash)

Returns a new Parameters instance with all keys from other_hash merged into current hash.

[ GitHub ]

  
# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 878

def merge(other_hash)
  new_instance_with_inherited_permitted_status(
    @parameters.merge(other_hash.to_h)
  )
end

#merge!(other_hash)

Returns the current Parameters instance with other_hash merged into current hash.

[ GitHub ]

  
# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 889

def merge!(other_hash, &block)
  @parameters.merge!(other_hash.to_h, &block)
  self
end

#permit(*filters)

Returns a new 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 if 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: [])

Sometimes it is not possible or convenient to declare the valid keys of a hash parameter or its internal structure. Just map to an empty hash:

params.permit(preferences: {})

Be careful because this opens the door to arbitrary input. In this case, permit ensures values in the returned structure are permitted scalars and filters out anything else.

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 permitted.

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

params.require(:person).permit(:contact)
# => #<ActionController::Parameters {} permitted: true>

params.require(:person).permit(contact: :phone)
# => #<ActionController::Parameters {"contact"=>#<ActionController::Parameters {"phone"=>"555-1234"} permitted: true>} permitted: true>

params.require(:person).permit(contact: [ :email, :phone ])
# => #<ActionController::Parameters {"contact"=>#<ActionController::Parameters {"email"=>"none@test.com", "phone"=>"555-1234"} permitted: true>} permitted: true>

If your parameters specify multiple parameters indexed by a number, you can permit each set of parameters under the numeric key to be the same using the same syntax as permitting a single item.

params = ActionController::Parameters.new({
  person: {
    '0': {
      email: "none@test.com",
      phone: "555-1234"
    },
    '1': {
      email: "nothing@test.com",
      phone: "555-6789"
    },
  }
})
params.permit(person: [:email]).to_h
# => {"person"=>{"0"=>{"email"=>"none@test.com"}, "1"=>{"email"=>"nothing@test.com"}}}

If you want to specify what keys you want from each numeric key, you can instead specify each one individually

params = ActionController::Parameters.new({
  person: {
    '0': {
      email: "none@test.com",
      phone: "555-1234"
    },
    '1': {
      email: "nothing@test.com",
      phone: "555-6789"
    },
  }
})
params.permit(person: { '0': [:email], '1': [:phone]}).to_h
# => {"person"=>{"0"=>{"email"=>"none@test.com"}, "1"=>{"phone"=>"555-6789"}}}
[ GitHub ]

  
# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 642

def permit(*filters)
  params = self.class.new

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

  unpermitted_parameters!(params) if self.class.action_on_unpermitted_parameters

  params.permit!
end

#permit!

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">
[ GitHub ]

  
# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 456

def permit!
  each_pair do |key, value|
    Array.wrap(value).flatten.each do |v|
      v.permit! if v.respond_to? :permit!
    end
  end

  @permitted = true
  self
end

#reject(&block)

Returns a new Parameters instance with items that the block evaluates to true removed.

[ GitHub ]

  
# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 830

def reject(&block)
  new_instance_with_inherited_permitted_status(@parameters.reject(&block))
end

#reject!(&block) Also known as: #delete_if

Removes items that the block evaluates to true and returns self.

[ GitHub ]

  
# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 835

def reject!(&block)
  @parameters.reject!(&block)
  self
end

#require(key) Also known as: #required

This method accepts both a single key and an array of keys.

When passed a single key, if it exists and its associated value is either present or the singleton false, returns said value:

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

Otherwise raises ParameterMissing:

ActionController::Parameters.new.require(:person)
# ActionController::ParameterMissing: param is missing or the value is empty: person

ActionController::Parameters.new(person: nil).require(:person)
# ActionController::ParameterMissing: param is missing or the value is empty: person

ActionController::Parameters.new(person: "\t").require(:person)
# ActionController::ParameterMissing: param is missing or the value is empty: person

ActionController::Parameters.new(person: {}).require(:person)
# ActionController::ParameterMissing: param is missing or the value is empty: person

When given an array of keys, the method tries to require each one of them in order. If it succeeds, an array with the respective return values is returned:

params = ActionController::Parameters.new(user: { ... }, profile: { ... })
user_params, profile_params = params.require([:user, :profile])

Otherwise, the method re-raises the first exception found:

params = ActionController::Parameters.new(user: {}, profile: {})
user_params, profile_params = params.require([:user, :profile])
# ActionController::ParameterMissing: param is missing or the value is empty: user

Technically this method can be used to fetch terminal values:

# CAREFUL
params = ActionController::Parameters.new(person: { name: "Finn" })
name = params.require(:person).require(:name) # CAREFUL

but take into account that at some point those ones have to be permitted:

def person_params
  params.require(:person).permit(:name).tap do |person_params|
    person_params.require(:name) # SAFER
  end
end

for example.

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# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 517

def require(key)
  return key.map { |k| require(k) } if key.is_a?(Array)
  value = self[key]
  if value.present? || value == false
    value
  else
    raise ParameterMissing.new(key, @parameters.keys)
  end
end

#required(key)

Alias for #require.

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# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 527

alias :required :require

#reverse_merge(other_hash) Also known as: #with_defaults

Returns a new Parameters instance with all keys from current hash merged into other_hash.

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# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 900

def reverse_merge(other_hash)
  new_instance_with_inherited_permitted_status(
    other_hash.to_h.merge(@parameters)
  )
end

#reverse_merge!(other_hash) Also known as: #with_defaults!

Returns the current Parameters instance with current hash merged into other_hash.

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# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 909

def reverse_merge!(other_hash)
  @parameters.merge!(other_hash.to_h) { |key, left, right| left }
  self
end

#select(&block)

Returns a new Parameters instance with only items that the block evaluates to true.

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# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 817

def select(&block)
  new_instance_with_inherited_permitted_status(@parameters.select(&block))
end

#select!(&block) Also known as: #keep_if

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

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# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 822

def select!(&block)
  @parameters.select!(&block)
  self
end

#slice(*keys)

Returns a new 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) # => #<ActionController::Parameters {"a"=>1, "b"=>2} permitted: false>
params.slice(:d)     # => #<ActionController::Parameters {} permitted: false>
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# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 721

def slice(*keys)
  new_instance_with_inherited_permitted_status(@parameters.slice(*keys))
end

#slice!(*keys)

Returns the current Parameters instance which contains only the given #keys.

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# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 727

def slice!(*keys)
  @parameters.slice!(*keys)
  self
end

#to_h(&block)

Returns a safe ::ActiveSupport::HashWithIndifferentAccess representation of the parameters with all unpermitted keys removed.

params = ActionController::Parameters.new({
  name: "Senjougahara Hitagi",
  oddity: "Heavy stone crab"
})
params.to_h
# => ActionController::UnfilteredParameters: unable to convert unpermitted parameters to hash

safe_params = params.permit(:name)
safe_params.to_h # => {"name"=>"Senjougahara Hitagi"}
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# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 326

def to_h(&block)
  if permitted?
    convert_parameters_to_hashes(@parameters, :to_h, &block)
  else
    raise UnfilteredParameters
  end
end

#to_hash

Returns a safe ::Hash representation of the parameters with all unpermitted keys removed.

params = ActionController::Parameters.new({
  name: "Senjougahara Hitagi",
  oddity: "Heavy stone crab"
})
params.to_hash
# => ActionController::UnfilteredParameters: unable to convert unpermitted parameters to hash

safe_params = params.permit(:name)
safe_params.to_hash # => {"name"=>"Senjougahara Hitagi"}
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# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 346

def to_hash
  to_h.to_hash
end

#to_param(*args)

Alias for #to_query.

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# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 379

alias_method :to_param, :to_query

#to_query(*args) Also known as: #to_param

Returns a string representation of the receiver suitable for use as a URL query string:

params = ActionController::Parameters.new({
  name: "David",
  nationality: "Danish"
})
params.to_query
# => ActionController::UnfilteredParameters: unable to convert unpermitted parameters to hash

safe_params = params.permit(:name, :nationality)
safe_params.to_query
# => "name=David&nationality=Danish"

An optional namespace can be passed to enclose key names:

params = ActionController::Parameters.new({
  name: "David",
  nationality: "Danish"
})
safe_params = params.permit(:name, :nationality)
safe_params.to_query("user")
# => "user%5Bname%5D=David&user%5Bnationality%5D=Danish"

The string pairs "key=value" that conform the query string are sorted lexicographically in ascending order.

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# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 376

def to_query(*args)
  to_h.to_query(*args)
end

#to_s ⇒ ?

Returns the content of the parameters as a string.

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# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 229

delegate :keys, :empty?, :exclude?, :include?,
  :as_json, :to_s, :each_key, to: :@parameters

#to_unsafe_h Also known as: #to_unsafe_hash

Returns an unsafe, unfiltered ::ActiveSupport::HashWithIndifferentAccess representation of the parameters.

params = ActionController::Parameters.new({
  name: "Senjougahara Hitagi",
  oddity: "Heavy stone crab"
})
params.to_unsafe_h
# => {"name"=>"Senjougahara Hitagi", "oddity" => "Heavy stone crab"}
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# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 390

def to_unsafe_h
  convert_parameters_to_hashes(@parameters, :to_unsafe_h)
end

#to_unsafe_hash

Alias for #to_unsafe_h.

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# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 393

alias_method :to_unsafe_hash, :to_unsafe_h

#transform_keys(&block)

Returns a new Parameters instance with the results of running block once for every key. The values are unchanged.

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# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 775

def transform_keys(&block)
  return to_enum(:transform_keys) unless block_given?
  new_instance_with_inherited_permitted_status(
    @parameters.transform_keys(&block)
  )
end

#transform_keys!(&block)

Performs keys transformation and returns the altered Parameters instance.

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# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 784

def transform_keys!(&block)
  return to_enum(:transform_keys!) unless block_given?
  @parameters.transform_keys!(&block)
  self
end

#transform_values

Returns a new Parameters instance 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 }
# => #<ActionController::Parameters {"a"=>2, "b"=>4, "c"=>6} permitted: false>
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# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 758

def transform_values
  return to_enum(:transform_values) unless block_given?
  new_instance_with_inherited_permitted_status(
    @parameters.transform_values { |v| yield convert_value_to_parameters(v) }
  )
end

#transform_values!

Performs values transformation and returns the altered Parameters instance.

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# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 767

def transform_values!
  return to_enum(:transform_values!) unless block_given?
  @parameters.transform_values! { |v| yield convert_value_to_parameters(v) }
  self
end

#value?(value)

Alias for #has_value?.

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# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 868

alias value? has_value?

#values

Returns a new array of the values of the parameters.

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# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 419

def values
  to_enum(:each_value).to_a
end

#values_at(*keys)

Returns values that were assigned to the given #keys. Note that all the ::Hash objects will be converted to Parameters.

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# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 872

def values_at(*keys)
  convert_value_to_parameters(@parameters.values_at(*keys))
end

#with_defaults(other_hash)

Alias for #reverse_merge.

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# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 905

alias_method :with_defaults, :reverse_merge

#with_defaults!(other_hash)

Alias for #reverse_merge!.

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# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 913

alias_method :with_defaults!, :reverse_merge!

#without(*keys)

Alias for #except.

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# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 741

alias_method :without, :except