class ActionController::Parameters

Action Controller Parameters

Allows you to choose which attributes should be permitted for mass updating and thus prevent accidentally exposing that which shouldn’t be exposed.

Provides methods for filtering and requiring params:

Examples:

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

permitted = params.expect(person: [:name, :age])
permitted # => #<ActionController::Parameters {"name"=>"Francesco", "age"=>22} permitted: true>

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

Parameters provides two options that control 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 {} 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 ActionController::Parameters using either :key or "key".

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

Constants

PERMITTED_SCALAR_TYPES

— Filtering ———————————————————-

This is a 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 one in the permit doc as well.

Attributes

parameters[R]
permitted[W]

Public Class Methods

new(parameters = {}, logging_context = {}) click to toggle source

Returns a new ActionController::Parameters instance. 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">
# File lib/action_controller/metal/strong_parameters.rb, line 287
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

Public Instance Methods

==(other) click to toggle source

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

Calls superclass method
# File lib/action_controller/metal/strong_parameters.rb, line 301
def ==(other)
  if other.respond_to?(:permitted?)
    permitted? == other.permitted? && parameters == other.parameters
  else
    super
  end
end
[](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] # => #<ActionController::Parameters {"name"=>"Francesco"} permitted: false>
params[:none]   # => nil
# File lib/action_controller/metal/strong_parameters.rb, line 797
def [](key)
  convert_hashes_to_parameters(key, @parameters[key])
end
[]=(key, value) click to toggle source

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

# File lib/action_controller/metal/strong_parameters.rb, line 803
def []=(key, value)
  @parameters[key] = value
end
as_json(options=nil) click to toggle source

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

# File lib/action_controller/metal/strong_parameters.rb, line 194
    
compact() click to toggle source

Returns a new ActionController::Parameters instance with nil values removed.

# File lib/action_controller/metal/strong_parameters.rb, line 974
def compact
  new_instance_with_inherited_permitted_status(@parameters.compact)
end
compact!() click to toggle source

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

# File lib/action_controller/metal/strong_parameters.rb, line 980
def compact!
  self if @parameters.compact!
end
compact_blank() click to toggle source

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

# File lib/action_controller/metal/strong_parameters.rb, line 986
def compact_blank
  reject { |_k, v| v.blank? }
end
compact_blank!() click to toggle source

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

# File lib/action_controller/metal/strong_parameters.rb, line 992
def compact_blank!
  reject! { |_k, v| v.blank? }
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 435
def converted_arrays
  @converted_arrays ||= Set.new
end
deep_dup() click to toggle source

Returns a duplicate ActionController::Parameters instance with the same permitted parameters.

# File lib/action_controller/metal/strong_parameters.rb, line 1092
def deep_dup
  self.class.new(@parameters.deep_dup, @logging_context).tap do |duplicate|
    duplicate.permitted = @permitted
  end
end
deep_merge(other_hash, &block) click to toggle source

Returns a new ActionController::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.

# File lib/action_controller/metal/strong_parameters.rb, line 168
    
deep_merge!(other_hash, &block) click to toggle source

Same as #deep_merge, but modifies self.

# File lib/action_controller/metal/strong_parameters.rb, line 183
    
deep_transform_keys(&block) click to toggle source

Returns a new ActionController::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.

# File lib/action_controller/metal/strong_parameters.rb, line 924
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) click to toggle source

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

# File lib/action_controller/metal/strong_parameters.rb, line 933
def deep_transform_keys!(&block)
  @parameters = _deep_transform_keys_in_object(@parameters, &block).to_unsafe_h
  self
end
delete(key, &block) click to toggle source

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 ActionController::Parameters object.

# File lib/action_controller/metal/strong_parameters.rb, line 942
def delete(key, &block)
  convert_value_to_parameters(@parameters.delete(key, &block))
end
delete_if(&block)
Alias for: reject!
dig(*keys) click to toggle source

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
# File lib/action_controller/metal/strong_parameters.rb, line 841
def dig(*keys)
  convert_hashes_to_parameters(keys.first, @parameters[keys.first])
  @parameters.dig(*keys)
end
each(&block)
Alias for: each_pair
each_key(&block) click to toggle source

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

# File lib/action_controller/metal/strong_parameters.rb, line 202
    
each_pair() { |key, convert_hashes_to_parameters(key, value)| ... } click to toggle source

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

# File lib/action_controller/metal/strong_parameters.rb, line 402
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
Also aliased as: each
each_value() { |convert_hashes_to_parameters(key, value)| ... } click to toggle source

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

# File lib/action_controller/metal/strong_parameters.rb, line 414
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?() click to toggle source

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

# File lib/action_controller/metal/strong_parameters.rb, line 211
    
eql?(other) click to toggle source
# File lib/action_controller/metal/strong_parameters.rb, line 309
def eql?(other)
  self.class == other.class &&
    permitted? == other.permitted? &&
    parameters.eql?(other.parameters)
end
except(*keys) click to toggle source

Returns a new ActionController::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>
# File lib/action_controller/metal/strong_parameters.rb, line 869
def except(*keys)
  new_instance_with_inherited_permitted_status(@parameters.except(*keys))
end
Also aliased as: without
exclude?(key) click to toggle source

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

# File lib/action_controller/metal/strong_parameters.rb, line 219
    
expect(*filters) click to toggle source

expect is the preferred way to require and permit parameters. It is safer than the previous recommendation to call permit and require in sequence, which could allow user triggered 500 errors.

expect is more strict with types to avoid a number of potential pitfalls that may be encountered with the .require.permit pattern.

For example:

params = ActionController::Parameters.new(comment: { text: "hello" })
params.expect(comment: [:text])
# => #<ActionController::Parameters { text: "hello" } permitted: true>

params = ActionController::Parameters.new(comment: [{ text: "hello" }, { text: "world" }])
params.expect(comment: [:text])
# => ActionController::ParameterMissing: param is missing or the value is empty or invalid: comment

In order to permit an array of parameters, the array must be defined explicitly. Use double array brackets, an array inside an array, to declare that an array of parameters is expected.

params = ActionController::Parameters.new(comments: [{ text: "hello" }, { text: "world" }])
params.expect(comments: [[:text]])
# => [#<ActionController::Parameters { "text" => "hello" } permitted: true>,
#     #<ActionController::Parameters { "text" => "world" } permitted: true>]

params = ActionController::Parameters.new(comments: { text: "hello" })
params.expect(comments: [[:text]])
# => ActionController::ParameterMissing: param is missing or the value is empty or invalid: comments

expect is intended to protect against array tampering.

params = ActionController::Parameters.new(user: "hack")
# The previous way of requiring and permitting parameters will error
params.require(:user).permit(:name, pets: [:name]) # wrong
# => NoMethodError: undefined method `permit' for an instance of String

# similarly with nested parameters
params = ActionController::Parameters.new(user: { name: "Martin", pets: { name: "hack" } })
user_params = params.require(:user).permit(:name, pets: [:name]) # wrong
# user_params[:pets] is expected to be an array but is a hash

expect solves this by being more strict with types.

params = ActionController::Parameters.new(user: "hack")
params.expect(user: [ :name, pets: [[:name]] ])
# => ActionController::ParameterMissing: param is missing or the value is empty or invalid: user

# with nested parameters
params = ActionController::Parameters.new(user: { name: "Martin", pets: { name: "hack" } })
user_params = params.expect(user: [:name, pets: [[:name]] ])
user_params[:pets] # => nil

As the examples show, expect requires the :user key, and any root keys similar to the .require.permit pattern. If multiple root keys are expected, they will all be required.

params = ActionController::Parameters.new(name: “Martin”, pies: [{ type: “dessert”, flavor: “pumpkin”}]) name, pies = params.expect(:name, pies: [[:type, :flavor]]) name # => “Martin” pies # => [#<ActionController::Parameters {“type”=>“dessert”, “flavor”=>“pumpkin”} permitted: true>]

When called with a hash with multiple keys, expect will permit the parameters and require the keys in the order they are given in the hash, returning an array of the permitted parameters.

params = ActionController::Parameters.new(subject: { name: “Martin” }, object: { pie: “pumpkin” }) subject, object = params.expect(subject: [:name], object: [:pie]) subject # =>

Besides being more strict about array vs hash params, expect uses permit internally, so it will behave similarly.

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

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

An array of permitted scalars may be expected with the following:

params = ActionController::Parameters.new(tags: ["rails", "parameters"])
permitted = params.expect(tags: [])
permitted.permitted?      # => true
permitted.is_a?(Array)    # => true
permitted.size            # => 2
# File lib/action_controller/metal/strong_parameters.rb, line 772
def expect(*filters)
  params = permit_filters(filters)
  keys = filters.flatten.flat_map { |f| f.is_a?(Hash) ? f.keys : f }
  values = params.require(keys)
  values.size == 1 ? values.first : values
end
expect!(*filters) click to toggle source

Same as expect, but raises an ActionController::ExpectedParameterMissing instead of ActionController::ParameterMissing. Unlike expect which will render a 400 response, expect! will raise an exception that is not handled. This is intended for debugging invalid params for an internal API where incorrectly formatted params would indicate a bug in a client library that should be fixed.

# File lib/action_controller/metal/strong_parameters.rb, line 786
def expect!(*filters)
  expect(*filters)
rescue ParameterMissing => e
  raise ExpectedParameterMissing.new(e.param, e.keys)
end
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) # => #<ActionController::Parameters {"a"=>1, "b"=>2} permitted: false>
params                  # => #<ActionController::Parameters {"c"=>3} permitted: false>
# File lib/action_controller/metal/strong_parameters.rb, line 879
def extract!(*keys)
  new_instance_with_inherited_permitted_status(@parameters.extract!(*keys))
end
extract_value(key, delimiter: "_") click to toggle source

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"]
# File lib/action_controller/metal/strong_parameters.rb, line 1110
def extract_value(key, delimiter: "_")
  @parameters[key]&.split(delimiter, -1)
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 a second argument is given, then that is returned (converted to an instance of ActionController::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 or invalid: none
params.fetch(:none, {})             # => #<ActionController::Parameters {} permitted: false>
params.fetch(:none, "Francesco")    # => "Francesco"
params.fetch(:none) { "Francesco" } # => "Francesco"
# File lib/action_controller/metal/strong_parameters.rb, line 820
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_key?
Alias for: include?
has_value?(value) click to toggle source

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

# File lib/action_controller/metal/strong_parameters.rb, line 997
def has_value?(value)
  each_value.include?(convert_value_to_parameters(value))
end
Also aliased as: value?
hash() click to toggle source
# File lib/action_controller/metal/strong_parameters.rb, line 315
def hash
  [self.class, @parameters, @permitted].hash
end
include?(key) click to toggle source

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

# File lib/action_controller/metal/strong_parameters.rb, line 227
    
Also aliased as: has_key?, key?, member?
inspect() click to toggle source
# File lib/action_controller/metal/strong_parameters.rb, line 1055
def inspect
  "#<#{self.class} #{@parameters} permitted: #{@permitted}>"
end
keep_if(&block)
Alias for: select!
key?
Alias for: include?
keys() click to toggle source

Returns a new array of the keys of the parameters.

# File lib/action_controller/metal/strong_parameters.rb, line 235
    
member?
Alias for: include?
merge(other_hash) click to toggle source

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

# File lib/action_controller/metal/strong_parameters.rb, line 1011
def merge(other_hash)
  new_instance_with_inherited_permitted_status(
    @parameters.merge(other_hash.to_h)
  )
end
merge!(other_hash) click to toggle source

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

# File lib/action_controller/metal/strong_parameters.rb, line 1022
def merge!(other_hash, &block)
  @parameters.merge!(other_hash.to_h, &block)
  self
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(name: "Francesco", age: 22, role: "admin")
permitted = params.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:

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

This has the added benefit of rejecting user-modified inputs that send a string when a hash is expected.

When followed by require, you can both filter and require parameters following the typical pattern of a Rails form. The expect method was made specifically for this use case and is the recommended way to require and permit parameters.

 permitted = params.expect(person: [:name, :age])

When using permit and require separately, pay careful attention to the order of the method calls.

 params = ActionController::Parameters.new(person: { name: "Martin", age: 40, role: "admin" })
 permitted = params.permit(person: [:name, :age]).require(:person) # correct

When require is used first, it is possible for users of your application to trigger a NoMethodError when the user, for example, sends a string for :person.

 params = ActionController::Parameters.new(person: "tampered")
 permitted = params.require(:person).permit(:name, :age) # not recommended
 # => NoMethodError: undefined method `permit' for an instance of String

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

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

params.permit(person: { contact: [ :email, :phone ] }).require(:person)
# => #<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"}}}
# File lib/action_controller/metal/strong_parameters.rb, line 668
def permit(*filters)
  permit_filters(filters, on_unpermitted: self.class.action_on_unpermitted_parameters, explicit_arrays: false)
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 461
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
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 445
def permitted?
  @permitted
end
reject(&block) click to toggle source

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

# File lib/action_controller/metal/strong_parameters.rb, line 961
def reject(&block)
  new_instance_with_inherited_permitted_status(@parameters.reject(&block))
end
reject!(&block) click to toggle source

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

# File lib/action_controller/metal/strong_parameters.rb, line 966
def reject!(&block)
  @parameters.reject!(&block)
  self
end
Also aliased as: delete_if
require(key) click to toggle source

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 ActionController::ParameterMissing:

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

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

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

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

This method is not recommended for fetching terminal values because it does not permit the values. For example, this can cause problems:

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

It is recommended to use expect instead:

def person_params
  # params.expect(person: :name).require(:name)
end
# File lib/action_controller/metal/strong_parameters.rb, line 519
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
Also aliased as: required
required(key)
Alias for: require
reverse_merge(other_hash) click to toggle source

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

# File lib/action_controller/metal/strong_parameters.rb, line 1033
def reverse_merge(other_hash)
  new_instance_with_inherited_permitted_status(
    other_hash.to_h.merge(@parameters)
  )
end
Also aliased as: with_defaults
reverse_merge!(other_hash) click to toggle source

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

# File lib/action_controller/metal/strong_parameters.rb, line 1042
def reverse_merge!(other_hash)
  @parameters.merge!(other_hash.to_h) { |key, left, right| left }
  self
end
Also aliased as: with_defaults!
select(&block) click to toggle source

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

# File lib/action_controller/metal/strong_parameters.rb, line 948
def select(&block)
  new_instance_with_inherited_permitted_status(@parameters.select(&block))
end
select!(&block) click to toggle source

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

# File lib/action_controller/metal/strong_parameters.rb, line 953
def select!(&block)
  @parameters.select!(&block)
  self
end
Also aliased as: keep_if
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) # => #<ActionController::Parameters {"a"=>1, "b"=>2} permitted: false>
params.slice(:d)     # => #<ActionController::Parameters {} permitted: false>
# File lib/action_controller/metal/strong_parameters.rb, line 852
def slice(*keys)
  new_instance_with_inherited_permitted_status(@parameters.slice(*keys))
end
slice!(*keys) click to toggle source

Returns the current ActionController::Parameters instance which contains only the given keys.

# File lib/action_controller/metal/strong_parameters.rb, line 858
def slice!(*keys)
  @parameters.slice!(*keys)
  self
end
to_h(&block) click to toggle source

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"}
# File lib/action_controller/metal/strong_parameters.rb, line 331
def to_h(&block)
  if permitted?
    convert_parameters_to_hashes(@parameters, :to_h, &block)
  else
    raise UnfilteredParameters
  end
end
to_hash() click to toggle source

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"}
# File lib/action_controller/metal/strong_parameters.rb, line 351
def to_hash
  to_h.to_hash
end
to_param(*args)
Alias for: to_query
to_query(*args) click to toggle source

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.

# File lib/action_controller/metal/strong_parameters.rb, line 381
def to_query(*args)
  to_h.to_query(*args)
end
Also aliased as: to_param
to_s() click to toggle source

Returns the content of the parameters as a string.

# File lib/action_controller/metal/strong_parameters.rb, line 250
delegate :keys, :empty?, :exclude?, :include?,
  :as_json, :to_s, :each_key, to: :@parameters
to_unsafe_h() click to toggle source

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"}
# File lib/action_controller/metal/strong_parameters.rb, line 395
def to_unsafe_h
  convert_parameters_to_hashes(@parameters, :to_unsafe_h)
end
Also aliased as: to_unsafe_hash
to_unsafe_hash()
Alias for: to_unsafe_h
transform_keys(&block) click to toggle source

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

# File lib/action_controller/metal/strong_parameters.rb, line 906
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) click to toggle source

Performs keys transformation and returns the altered ActionController::Parameters instance.

# File lib/action_controller/metal/strong_parameters.rb, line 915
def transform_keys!(&block)
  return to_enum(:transform_keys!) unless block_given?
  @parameters.transform_keys!(&block)
  self
end
transform_values() { |convert_value_to_parameters(v)| ... } click to toggle source

Returns a new ActionController::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>
# File lib/action_controller/metal/strong_parameters.rb, line 889
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!() { |convert_value_to_parameters(v)| ... } click to toggle source

Performs values transformation and returns the altered ActionController::Parameters instance.

# File lib/action_controller/metal/strong_parameters.rb, line 898
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?
values() click to toggle source

Returns a new array of the values of the parameters.

# File lib/action_controller/metal/strong_parameters.rb, line 424
def values
  to_enum(:each_value).to_a
end
values_at(*keys) click to toggle source

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

# File lib/action_controller/metal/strong_parameters.rb, line 1005
def values_at(*keys)
  convert_value_to_parameters(@parameters.values_at(*keys))
end
with_defaults(other_hash)
Alias for: reverse_merge
with_defaults!(other_hash)
Alias for: reverse_merge!
without(*keys)
Alias for: except

Protected Instance Methods

each_nested_attribute() { |v| ... } click to toggle source
# File lib/action_controller/metal/strong_parameters.rb, line 1123
def each_nested_attribute
  hash = self.class.new
  self.each { |k, v| hash[k] = yield v if Parameters.nested_attribute?(k, v) }
  hash
end
nested_attributes?() click to toggle source
# File lib/action_controller/metal/strong_parameters.rb, line 1119
def nested_attributes?
  @parameters.any? { |k, v| Parameters.nested_attribute?(k, v) }
end
permit_filters(filters, on_unpermitted: nil, explicit_arrays: true) click to toggle source

Filters self and optionally checks for unpermitted keys

# File lib/action_controller/metal/strong_parameters.rb, line 1130
def permit_filters(filters, on_unpermitted: nil, explicit_arrays: true)
  params = self.class.new

  filters.flatten.each do |filter|
    case filter
    when Symbol, String
      # Declaration [:name, "age"]
      permitted_scalar_filter(params, filter)
    when Hash
      # Declaration [{ person: ... }]
      hash_filter(params, filter, on_unpermitted:, explicit_arrays:)
    end
  end

  unpermitted_parameters!(params, on_unpermitted:)

  params.permit!
end

Private Instance Methods

_deep_transform_keys_in_object(object) { |key| ... } click to toggle source
# File lib/action_controller/metal/strong_parameters.rb, line 1192
def _deep_transform_keys_in_object(object, &block)
  case object
  when Hash
    object.each_with_object(self.class.new) do |(key, value), result|
      result[yield(key)] = _deep_transform_keys_in_object(value, &block)
    end
  when Parameters
    if object.permitted?
      object.to_h.deep_transform_keys(&block)
    else
      object.to_unsafe_h.deep_transform_keys(&block)
    end
  when Array
    object.map { |e| _deep_transform_keys_in_object(e, &block) }
  else
    object
  end
end
_deep_transform_keys_in_object!(object) { |key| ... } click to toggle source
# File lib/action_controller/metal/strong_parameters.rb, line 1211
def _deep_transform_keys_in_object!(object, &block)
  case object
  when Hash
    object.keys.each do |key|
      value = object.delete(key)
      object[yield(key)] = _deep_transform_keys_in_object!(value, &block)
    end
    object
  when Parameters
    if object.permitted?
      object.to_h.deep_transform_keys!(&block)
    else
      object.to_unsafe_h.deep_transform_keys!(&block)
    end
  when Array
    object.map! { |e| _deep_transform_keys_in_object!(e, &block) }
  else
    object
  end
end
array_filter?(filter) click to toggle source

When an array is expected, you must specify an array explicitly using the following format:

params.expect(comments: [[:flavor]])

Which will match only the following array formats:

{ pies: [{ flavor: "rhubarb" }, { flavor: "apple" }] }
{ pies: { "0" => { flavor: "key lime" }, "1" =>  { flavor: "mince" } } }

When using permit, arrays are specified the same way as hashes:

params.expect(pies: [:flavor])

In this case, permit would also allow matching with a hash (or vice versa):

{ pies: { flavor: "cherry" } }
# File lib/action_controller/metal/strong_parameters.rb, line 1256
def array_filter?(filter)
  filter.is_a?(Array) && filter.size == 1 && filter.first.is_a?(Array)
end
convert_hashes_to_parameters(key, value) click to toggle source
# File lib/action_controller/metal/strong_parameters.rb, line 1172
def convert_hashes_to_parameters(key, value)
  converted = convert_value_to_parameters(value)
  @parameters[key] = converted unless converted.equal?(value)
  converted
end
convert_parameters_to_hashes(value, using, &block) click to toggle source
# File lib/action_controller/metal/strong_parameters.rb, line 1156
def convert_parameters_to_hashes(value, using, &block)
  case value
  when Array
    value.map { |v| convert_parameters_to_hashes(v, using) }
  when Hash
    transformed = value.transform_values do |v|
      convert_parameters_to_hashes(v, using)
    end
    (block_given? ? transformed.to_h(&block) : transformed).with_indifferent_access
  when Parameters
    value.send(using)
  else
    value
  end
end
convert_value_to_parameters(value) click to toggle source
# File lib/action_controller/metal/strong_parameters.rb, line 1178
def convert_value_to_parameters(value)
  case value
  when Array
    return value if converted_arrays.member?(value)
    converted = value.map { |_| convert_value_to_parameters(_) }
    converted_arrays << converted.dup
    converted
  when Hash
    self.class.new(value, @logging_context)
  else
    value
  end
end
each_array_element(object, filter, &block) click to toggle source

Called when an explicit array filter is encountered.

# File lib/action_controller/metal/strong_parameters.rb, line 1261
def each_array_element(object, filter, &block)
  case object
  when Array
    object.grep(Parameters).filter_map(&block)
  when Parameters
    if object.nested_attributes? && !specify_numeric_keys?(filter)
      object.each_nested_attribute(&block)
    end
  end
end
hash_filter(params, filter, on_unpermitted: self.class.action_on_unpermitted_parameters, explicit_arrays: false) click to toggle source
# File lib/action_controller/metal/strong_parameters.rb, line 1352
def hash_filter(params, filter, on_unpermitted: self.class.action_on_unpermitted_parameters, explicit_arrays: false)
  filter = filter.with_indifferent_access

  # Slicing filters out non-declared keys.
  slice(*filter.keys).each do |key, value|
    next unless value
    next unless has_key? key
    result = permit_value(value, filter[key], on_unpermitted:, explicit_arrays:)
    params[key] = result unless result.nil?
  end
end
initialize_copy(source) click to toggle source
Calls superclass method
# File lib/action_controller/metal/strong_parameters.rb, line 1437
def initialize_copy(source)
  super
  @parameters = @parameters.dup
end
new_instance_with_inherited_permitted_status(hash) click to toggle source
# File lib/action_controller/metal/strong_parameters.rb, line 1150
def new_instance_with_inherited_permitted_status(hash)
  self.class.new(hash, @logging_context).tap do |new_instance|
    new_instance.permitted = @permitted
  end
end
non_scalar?(value) click to toggle source
# File lib/action_controller/metal/strong_parameters.rb, line 1346
def non_scalar?(value)
  value.is_a?(Array) || value.is_a?(Parameters)
end
permit_any_in_array(array) click to toggle source
# File lib/action_controller/metal/strong_parameters.rb, line 1420
def permit_any_in_array(array)
  [].tap do |sanitized|
    array.each do |element|
      case element
      when ->(e) { permitted_scalar?(e) }
        sanitized << element
      when Array
        sanitized << permit_any_in_array(element)
      when Parameters
        sanitized << permit_any_in_parameters(element)
      else
        # Filter this one out.
      end
    end
  end
end
permit_any_in_parameters(params) click to toggle source
# File lib/action_controller/metal/strong_parameters.rb, line 1403
def permit_any_in_parameters(params)
  self.class.new.tap do |sanitized|
    params.each do |key, value|
      case value
      when ->(v) { permitted_scalar?(v) }
        sanitized[key] = value
      when Array
        sanitized[key] = permit_any_in_array(value)
      when Parameters
        sanitized[key] = permit_any_in_parameters(value)
      else
        # Filter this one out.
      end
    end
  end
end
permit_array_of_hashes(value, filter, on_unpermitted:, explicit_arrays:) click to toggle source
# File lib/action_controller/metal/strong_parameters.rb, line 1382
def permit_array_of_hashes(value, filter, on_unpermitted:, explicit_arrays:)
  each_array_element(value, filter) do |element|
    element.permit_filters(Array.wrap(filter), on_unpermitted:, explicit_arrays:)
  end
end
permit_array_of_scalars(value) click to toggle source
# File lib/action_controller/metal/strong_parameters.rb, line 1378
def permit_array_of_scalars(value)
  value if value.is_a?(Array) && value.all? { |element| permitted_scalar?(element) }
end
permit_hash(value, filter, on_unpermitted:, explicit_arrays:) click to toggle source
# File lib/action_controller/metal/strong_parameters.rb, line 1388
def permit_hash(value, filter, on_unpermitted:, explicit_arrays:)
  return unless value.is_a?(Parameters)

  if filter == EMPTY_HASH
    permit_any_in_parameters(value)
  else
    value.permit_filters(Array.wrap(filter), on_unpermitted:, explicit_arrays:)
  end
end
permit_hash_or_array(value, filter, on_unpermitted:, explicit_arrays:) click to toggle source
# File lib/action_controller/metal/strong_parameters.rb, line 1398
def permit_hash_or_array(value, filter, on_unpermitted:, explicit_arrays:)
  permit_array_of_hashes(value, filter, on_unpermitted:, explicit_arrays:) ||
    permit_hash(value, filter, on_unpermitted:, explicit_arrays:)
end
permit_value(value, filter, on_unpermitted:, explicit_arrays:) click to toggle source
# File lib/action_controller/metal/strong_parameters.rb, line 1364
def permit_value(value, filter, on_unpermitted:,  explicit_arrays:)
  if filter == EMPTY_ARRAY # Declaration { comment_ids: [] }.
    permit_array_of_scalars(value)
  elsif filter == EMPTY_HASH # Declaration { preferences: {} }.
    permit_hash(value, filter, on_unpermitted:, explicit_arrays:)
  elsif array_filter?(filter) # Declaration { comments: [[:text]] }
    permit_array_of_hashes(value, filter.first, on_unpermitted:, explicit_arrays:)
  elsif explicit_arrays # Declaration { user: { address: ... } } or { user: [:name, ...] } (only allows hash value)
    permit_hash(value, filter, on_unpermitted:, explicit_arrays:)
  elsif non_scalar?(value) # Declaration { user: { address: ... } } or { user: [:name, ...] }
    permit_hash_or_array(value, filter, on_unpermitted:, explicit_arrays:)
  end
end
permitted_scalar?(value) click to toggle source
# File lib/action_controller/metal/strong_parameters.rb, line 1317
def permitted_scalar?(value)
  PERMITTED_SCALAR_TYPES.any? { |type| value.is_a?(type) }
end
permitted_scalar_filter(params, permitted_key) click to toggle source

Adds existing keys to the params if their values are scalar.

For example:

puts self.keys #=> ["zipcode(90210i)"]
params = {}

permitted_scalar_filter(params, "zipcode")

puts params.keys # => ["zipcode"]
# File lib/action_controller/metal/strong_parameters.rb, line 1331
def permitted_scalar_filter(params, permitted_key)
  permitted_key = permitted_key.to_s

  if has_key?(permitted_key) && permitted_scalar?(self[permitted_key])
    params[permitted_key] = self[permitted_key]
  end

  each_key do |key|
    next unless key =~ /\(\d+[if]?\)\z/
    next unless $~.pre_match == permitted_key

    params[key] = self[key] if permitted_scalar?(self[key])
  end
end
specify_numeric_keys?(filter) click to toggle source
# File lib/action_controller/metal/strong_parameters.rb, line 1232
def specify_numeric_keys?(filter)
  if filter.respond_to?(:keys)
    filter.keys.any? { |key| /\A-?\d+\z/.match?(key) }
  end
end
unpermitted_keys(params) click to toggle source
# File lib/action_controller/metal/strong_parameters.rb, line 1286
def unpermitted_keys(params)
  keys - params.keys - always_permitted_parameters
end
unpermitted_parameters!(params, on_unpermitted: self.class.action_on_unpermitted_parameters) click to toggle source
# File lib/action_controller/metal/strong_parameters.rb, line 1272
def unpermitted_parameters!(params, on_unpermitted: self.class.action_on_unpermitted_parameters)
  return unless on_unpermitted
  unpermitted_keys = unpermitted_keys(params)
  if unpermitted_keys.any?
    case on_unpermitted
    when :log
      name = "unpermitted_parameters.action_controller"
      ActiveSupport::Notifications.instrument(name, keys: unpermitted_keys, context: @logging_context)
    when :raise
      raise ActionController::UnpermittedParameters.new(unpermitted_keys)
    end
  end
end