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 actionpack/lib/action_controller/metal/strong_parameters.rb, line 288
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

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

# File actionpack/lib/action_controller/metal/strong_parameters.rb, line 302
def ==(other)
  if other.respond_to?(:permitted?)
    permitted? == other.permitted? && parameters == other.parameters
  else
    super
  end
end

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 actionpack/lib/action_controller/metal/strong_parameters.rb, line 670
def [](key)
  convert_hashes_to_parameters(key, @parameters[key])
end

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

# File actionpack/lib/action_controller/metal/strong_parameters.rb, line 676
def []=(key, value)
  @parameters[key] = value
end

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

# File actionpack/lib/action_controller/metal/strong_parameters.rb, line 181
    

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

# File actionpack/lib/action_controller/metal/strong_parameters.rb, line 847
def compact
  new_instance_with_inherited_permitted_status(@parameters.compact)
end

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

# File actionpack/lib/action_controller/metal/strong_parameters.rb, line 853
def compact!
  self if @parameters.compact!
end

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

# File actionpack/lib/action_controller/metal/strong_parameters.rb, line 859
def compact_blank
  reject { |_k, v| v.blank? }
end

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

# File actionpack/lib/action_controller/metal/strong_parameters.rb, line 865
def compact_blank!
  reject! { |_k, v| v.blank? }
end

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 actionpack/lib/action_controller/metal/strong_parameters.rb, line 436
def converted_arrays
  @converted_arrays ||= Set.new
end

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

# File actionpack/lib/action_controller/metal/strong_parameters.rb, line 965
def deep_dup
  self.class.new(@parameters.deep_dup, @logging_context).tap do |duplicate|
    duplicate.permitted = @permitted
  end
end

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 actionpack/lib/action_controller/metal/strong_parameters.rb, line 155
    

Same as deep_merge, but modifies self.

# File actionpack/lib/action_controller/metal/strong_parameters.rb, line 170
    

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 actionpack/lib/action_controller/metal/strong_parameters.rb, line 797
def deep_transform_keys(&block)
  new_instance_with_inherited_permitted_status(
    _deep_transform_keys_in_object(@parameters, &block).to_unsafe_h
  )
end

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 actionpack/lib/action_controller/metal/strong_parameters.rb, line 806
def deep_transform_keys!(&block)
  @parameters = _deep_transform_keys_in_object(@parameters, &block).to_unsafe_h
  self
end

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 actionpack/lib/action_controller/metal/strong_parameters.rb, line 815
def delete(key, &block)
  convert_value_to_parameters(@parameters.delete(key, &block))
end

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 actionpack/lib/action_controller/metal/strong_parameters.rb, line 714
def dig(*keys)
  convert_hashes_to_parameters(keys.first, @parameters[keys.first])
  @parameters.dig(*keys)
end

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

# File actionpack/lib/action_controller/metal/strong_parameters.rb, line 189
    

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

# File actionpack/lib/action_controller/metal/strong_parameters.rb, line 403
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

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

# File actionpack/lib/action_controller/metal/strong_parameters.rb, line 415
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

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

# File actionpack/lib/action_controller/metal/strong_parameters.rb, line 198
    

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 actionpack/lib/action_controller/metal/strong_parameters.rb, line 742
def except(*keys)
  new_instance_with_inherited_permitted_status(@parameters.except(*keys))
end

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

# File actionpack/lib/action_controller/metal/strong_parameters.rb, line 206
    

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 actionpack/lib/action_controller/metal/strong_parameters.rb, line 752
def extract!(*keys)
  new_instance_with_inherited_permitted_status(@parameters.extract!(*keys))
end

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 actionpack/lib/action_controller/metal/strong_parameters.rb, line 983
def extract_value(key, delimiter: "_")
  @parameters[key]&.split(delimiter, -1)
end

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: none
params.fetch(:none, {})             # => #<ActionController::Parameters {} permitted: false>
params.fetch(:none, "Francesco")    # => "Francesco"
params.fetch(:none) { "Francesco" } # => "Francesco"

# File actionpack/lib/action_controller/metal/strong_parameters.rb, line 693
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

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

# File actionpack/lib/action_controller/metal/strong_parameters.rb, line 870
def has_value?(value)
  each_value.include?(convert_value_to_parameters(value))
end

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

# File actionpack/lib/action_controller/metal/strong_parameters.rb, line 214
    

Returns a new array of the keys of the parameters.

# File actionpack/lib/action_controller/metal/strong_parameters.rb, line 222
    

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

# File actionpack/lib/action_controller/metal/strong_parameters.rb, line 884
def merge(other_hash)
  new_instance_with_inherited_permitted_status(
    @parameters.merge(other_hash.to_h)
  )
end

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

# File actionpack/lib/action_controller/metal/strong_parameters.rb, line 895
def merge!(other_hash, &block)
  @parameters.merge!(other_hash.to_h, &block)
  self
end

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 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"}}}

# File actionpack/lib/action_controller/metal/strong_parameters.rb, line 648
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

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 actionpack/lib/action_controller/metal/strong_parameters.rb, line 462
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

Returns true if the parameter is permitted, false otherwise.

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

# File actionpack/lib/action_controller/metal/strong_parameters.rb, line 446
def permitted?
  @permitted
end

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

# File actionpack/lib/action_controller/metal/strong_parameters.rb, line 834
def reject(&block)
  new_instance_with_inherited_permitted_status(@parameters.reject(&block))
end

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

# File actionpack/lib/action_controller/metal/strong_parameters.rb, line 839
def reject!(&block)
  @parameters.reject!(&block)
  self
end

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: 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.

# File actionpack/lib/action_controller/metal/strong_parameters.rb, line 522
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

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

# File actionpack/lib/action_controller/metal/strong_parameters.rb, line 906
def reverse_merge(other_hash)
  new_instance_with_inherited_permitted_status(
    other_hash.to_h.merge(@parameters)
  )
end

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

# File actionpack/lib/action_controller/metal/strong_parameters.rb, line 915
def reverse_merge!(other_hash)
  @parameters.merge!(other_hash.to_h) { |key, left, right| left }
  self
end

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

# File actionpack/lib/action_controller/metal/strong_parameters.rb, line 821
def select(&block)
  new_instance_with_inherited_permitted_status(@parameters.select(&block))
end

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

# File actionpack/lib/action_controller/metal/strong_parameters.rb, line 826
def select!(&block)
  @parameters.select!(&block)
  self
end

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 actionpack/lib/action_controller/metal/strong_parameters.rb, line 725
def slice(*keys)
  new_instance_with_inherited_permitted_status(@parameters.slice(*keys))
end

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

# File actionpack/lib/action_controller/metal/strong_parameters.rb, line 731
def slice!(*keys)
  @parameters.slice!(*keys)
  self
end

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 actionpack/lib/action_controller/metal/strong_parameters.rb, line 332
def to_h(&block)
  if permitted?
    convert_parameters_to_hashes(@parameters, :to_h, &block)
  else
    raise UnfilteredParameters
  end
end

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 actionpack/lib/action_controller/metal/strong_parameters.rb, line 352
def to_hash
  to_h.to_hash
end

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 actionpack/lib/action_controller/metal/strong_parameters.rb, line 382
def to_query(*args)
  to_h.to_query(*args)
end

Returns the content of the parameters as a string.

# File actionpack/lib/action_controller/metal/strong_parameters.rb, line 237
delegate :keys, :empty?, :exclude?, :include?,
  :as_json, :to_s, :each_key, to: :@parameters

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 actionpack/lib/action_controller/metal/strong_parameters.rb, line 396
def to_unsafe_h
  convert_parameters_to_hashes(@parameters, :to_unsafe_h)
end

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

# File actionpack/lib/action_controller/metal/strong_parameters.rb, line 779
def transform_keys(&block)
  return to_enum(:transform_keys) unless block_given?
  new_instance_with_inherited_permitted_status(
    @parameters.transform_keys(&block)
  )
end

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

# File actionpack/lib/action_controller/metal/strong_parameters.rb, line 788
def transform_keys!(&block)
  return to_enum(:transform_keys!) unless block_given?
  @parameters.transform_keys!(&block)
  self
end

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 actionpack/lib/action_controller/metal/strong_parameters.rb, line 762
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

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

# File actionpack/lib/action_controller/metal/strong_parameters.rb, line 771
def transform_values!
  return to_enum(:transform_values!) unless block_given?
  @parameters.transform_values! { |v| yield convert_value_to_parameters(v) }
  self
end

Returns a new array of the values of the parameters.

# File actionpack/lib/action_controller/metal/strong_parameters.rb, line 425
def values
  to_enum(:each_value).to_a
end

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

# File actionpack/lib/action_controller/metal/strong_parameters.rb, line 878
def values_at(*keys)
  convert_value_to_parameters(@parameters.values_at(*keys))
end