class ActionController::Parameters

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 124
def initialize(attributes = nil)
  super(attributes)
  @permitted = self.class.permit_all_parameters
end

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

params = ActionController::Parameters.new(person: { name: 'Francesco' })
params[:person] # => {"name"=>"Francesco"}
params[:none]   # => nil

# File actionpack/lib/action_controller/metal/strong_parameters.rb, line 286
def [](key)
  convert_hashes_to_parameters(key, super)
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.

# File actionpack/lib/action_controller/metal/strong_parameters.rb, line 132
def converted_arrays
  @converted_arrays ||= Set.new
end

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

params = ActionController::Parameters.new(a: 1)
params.permit!
params.permitted?        # => true
copy_params = params.dup # => {"a"=>1}
copy_params.permitted?   # => true

# File actionpack/lib/action_controller/metal/strong_parameters.rb, line 328
def dup
  super.tap do |duplicate|
    duplicate.permitted = @permitted
  end
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)               # => {"name"=>"Francesco"}
params.fetch(:none)                 # => ActionController::ParameterMissing: param not found: none
params.fetch(:none, 'Francesco')    # => "Francesco"
params.fetch(:none) { 'Francesco' } # => "Francesco"

# File actionpack/lib/action_controller/metal/strong_parameters.rb, line 301
def fetch(key, *args)
  convert_hashes_to_parameters(key, super, false)
rescue KeyError
  raise ActionController::ParameterMissing.new(key)
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 it is a key of params whose associated value is of type String, Symbol, NilClass, Numeric, TrueClass, FalseClass, Date, Time, DateTime, StringIO, IO, ActionDispatch::Http::UploadedFile or Rack::Test::UploadedFile. Otherwise, the key :name is filtered out.

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

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

You can also use permit on nested parameters, like:

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

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

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

params = ActionController::Parameters.new({
  person: {
    contact: {
      email: '[email protected]',
      phone: '555-1234'
    }
  }
})

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

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

params.require(:person).permit(contact: [ :email, :phone ])
# => {"contact"=>{"email"=>"[email protected]", "phone"=>"555-1234"}}

# File actionpack/lib/action_controller/metal/strong_parameters.rb, line 263
def permit(*filters)
  params = self.class.new

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

  unpermitted_parameters!(params) if self.class.action_on_unpermitted_parameters

  params.permit!
end

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 158
def permit!
  each_pair do |key, value|
    value = convert_hashes_to_parameters(key, value)
    Array.wrap(value).each do |_|
      _.permit! if _.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 142
def permitted?
  @permitted
end

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

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

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

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

# File actionpack/lib/action_controller/metal/strong_parameters.rb, line 182
def require(key)
  value = self[key]
  if value.present? || value == false
    value
  else
    raise ParameterMissing.new(key)
  end
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) # => {"a"=>1, "b"=>2}
params.slice(:d)     # => {}

# File actionpack/lib/action_controller/metal/strong_parameters.rb, line 314
def slice(*keys)
  self.class.new(super).tap do |new_instance|
    new_instance.permitted = @permitted
  end
end