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

class Person < ActiveRecord::Base
end

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

ActionController::Parameters.permit_all_parameters = true

params = ActionController::Parameters.new(name: "Francesco")
params.permitted?  # => true
Person.new(params) # => #<Person id: nil, name: "Francesco">

# File actionpack/lib/action_controller/metal/strong_parameters.rb, line 234
def initialize(parameters = {})
  @parameters = parameters.with_indifferent_access
  @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 241
def ==(other)
  if other.respond_to?(:permitted?)
    permitted? == other.permitted? && parameters == other.parameters
  else
    @parameters == other
  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 545
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 551
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 135
    

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 344
def converted_arrays
  @converted_arrays ||= Set.new
end

Returns duplicate of object including all parameters.

# File actionpack/lib/action_controller/metal/strong_parameters.rb, line 781
def deep_dup
  self.class.new(@parameters.deep_dup).tap do |duplicate|
    duplicate.permitted = @permitted
  end
end

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

# File actionpack/lib/action_controller/metal/strong_parameters.rb, line 676
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 588
def dig(*keys)
  convert_value_to_parameters(@parameters.dig(*keys))
end

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 330
def each_pair(&block)
  @parameters.each_pair do |key, value|
    yield key, convert_hashes_to_parameters(key, value)
  end
end

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

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

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 617
def except(*keys)
  new_instance_with_inherited_permitted_status(@parameters.except(*keys))
end

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 626
def extract!(*keys)
  new_instance_with_inherited_permitted_status(@parameters.extract!(*keys))
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 more arguments are given, then that will be returned; if a block is given, then that will be run and its result returned.

params = ActionController::Parameters.new(person: { name: "Francesco" })
params.fetch(:person)               # => <ActionController::Parameters {"name"=>"Francesco"} permitted: false>
params.fetch(:none)                 # => ActionController::ParameterMissing: param is missing or the value is empty: none
params.fetch(:none, "Francesco")    # => "Francesco"
params.fetch(:none) { "Francesco" } # => "Francesco"

# File actionpack/lib/action_controller/metal/strong_parameters.rb, line 566
def fetch(key, *args)
  convert_value_to_parameters(
    @parameters.fetch(key) {
      if block_given?
        yield
      else
        args.fetch(0) { raise ActionController::ParameterMissing.new(key) }
      end
    }
  )
end

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

# File actionpack/lib/action_controller/metal/strong_parameters.rb, line 151
    

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

# File actionpack/lib/action_controller/metal/strong_parameters.rb, line 159
    

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

# File actionpack/lib/action_controller/metal/strong_parameters.rb, line 167
    

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

# File actionpack/lib/action_controller/metal/strong_parameters.rb, line 175
    

Returns a new array of the keys of the parameters.

# File actionpack/lib/action_controller/metal/strong_parameters.rb, line 183
    

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

# File actionpack/lib/action_controller/metal/strong_parameters.rb, line 714
def merge(other_hash)
  new_instance_with_inherited_permitted_status(
    @parameters.merge(other_hash.to_h)
  )
end

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

# File actionpack/lib/action_controller/metal/strong_parameters.rb, line 722
def merge!(other_hash)
  @parameters.merge!(other_hash.to_h)
  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 whitelisted.

params = ActionController::Parameters.new({
  person: {
    contact: {
      email: "[email protected]",
      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"=>"[email protected]", "phone"=>"555-1234"} permitted: true>} permitted: true>

# File actionpack/lib/action_controller/metal/strong_parameters.rb, line 522
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 370
def permit!
  each_pair do |key, value|
    Array.wrap(value).each do |v|
      v.permit! if v.respond_to? :permit!
    end
  end

  @permitted = true
  self
end

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 354
def permitted?
  @permitted
end

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

# File actionpack/lib/action_controller/metal/strong_parameters.rb, line 695
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 700
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 431
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)
  end
end

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

# File actionpack/lib/action_controller/metal/strong_parameters.rb, line 729
def reverse_merge(other_hash)
  new_instance_with_inherited_permitted_status(
    other_hash.to_h.merge(@parameters)
  )
end

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

# File actionpack/lib/action_controller/metal/strong_parameters.rb, line 737
def reverse_merge!(other_hash)
  @parameters.merge!(other_hash.to_h) { |key, left, right| left }
  self
end

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

# File actionpack/lib/action_controller/metal/strong_parameters.rb, line 682
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 687
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 600
def slice(*keys)
  new_instance_with_inherited_permitted_status(@parameters.slice(*keys))
end

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

# File actionpack/lib/action_controller/metal/strong_parameters.rb, line 606
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 unfiltered 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 261
def to_h
  if permitted?
    convert_parameters_to_hashes(@parameters, :to_h)
  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 unfiltered 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 281
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
# => "name=David&nationality=Danish"

An optional namespace can be passed to enclose key names:

params = ActionController::Parameters.new({
  name: "David",
  nationality: "Danish"
})
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.

This method is also aliased as to_param.

# File actionpack/lib/action_controller/metal/strong_parameters.rb, line 308
def to_query(*args)
  to_h.to_query(*args)
end

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 323
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 655
def transform_keys(&block)
  if block
    new_instance_with_inherited_permitted_status(
      @parameters.transform_keys(&block)
    )
  else
    @parameters.transform_keys
  end
end

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

# File actionpack/lib/action_controller/metal/strong_parameters.rb, line 667
def transform_keys!(&block)
  @parameters.transform_keys!(&block)
  self
end

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

params = ActionController::Parameters.new(a: 1, b: 2, c: 3)
params.transform_values { |x| x * 2 }
# => <ActionController::Parameters {"a"=>2, "b"=>4, "c"=>6} permitted: false>

# File actionpack/lib/action_controller/metal/strong_parameters.rb, line 636
def transform_values(&block)
  if block
    new_instance_with_inherited_permitted_status(
      @parameters.transform_values(&block)
    )
  else
    @parameters.transform_values
  end
end

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

# File actionpack/lib/action_controller/metal/strong_parameters.rb, line 648
def transform_values!(&block)
  @parameters.transform_values!(&block)
  self
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 198
    

Returns a new array of the values of the parameters.

# File actionpack/lib/action_controller/metal/strong_parameters.rb, line 205
delegate :keys, :key?, :has_key?, :values, :has_value?, :value?, :empty?, :include?,
  :as_json, :to_s, to: :@parameters

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 708
def values_at(*keys)
  convert_value_to_parameters(@parameters.values_at(*keys))
end