Class: ActionController::Parameters

Inherits:
ActiveSupport::HashWithIndifferentAccess show all
Defined in:
actionpack/lib/action_controller/metal/strong_parameters.rb

Overview

Action Controller Parameters

Allows to choose which attributes should be whitelisted for mass updating and thus prevent accidentally exposing that which shouldn't be exposed. Provides two methods for this purpose: #require and #permit. The former is used to mark parameters as required. The latter is used to set the parameter as permitted and limit which attributes should be allowed for mass updating.

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

permitted = params.require(:person).permit(:name, :age)
permitted            # => {"name"=>"Francesco", "age"=>22}
permitted.class      # => ActionController::Parameters
permitted.permitted? # => true

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

It provides two options that controls the top-level behavior of new instances:

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

  • action_on_unpermitted_parameters - Allow to control the behavior when parameters that are not explicitly permitted are found. The values can be :log to write a message on the logger or :raise to raise ActionController::UnpermittedParameters exception. The default value is :log in test and development environments, false otherwise.

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.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.

ActionController::Parameters inherits from ActiveSupport::HashWithIndifferentAccess, this means that you can fetch values using either :key or "key".

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

Class Method Summary collapse

Instance Method Summary collapse

Methods inherited from ActiveSupport::HashWithIndifferentAccess

[], #[]=, #compact, #deep_stringify_keys, #deep_stringify_keys!, #deep_symbolize_keys, #default, #extractable_options?, #key?, #merge, #nested_under_indifferent_access, new_from_hash_copying_default, #regular_update, #regular_writer, #reject, #replace, #reverse_merge, #reverse_merge!, #select, #stringify_keys, #stringify_keys!, #symbolize_keys, #to_hash, #to_options!, #update, #values_at, #with_indifferent_access

Methods inherited from Hash

#as_json, #assert_valid_keys, #compact, #compact!, #deep_dup, #deep_merge, #deep_merge!, #deep_stringify_keys, #deep_stringify_keys!, #deep_symbolize_keys, #deep_symbolize_keys!, #deep_transform_keys, #deep_transform_keys!, #except, #except!, #extractable_options?, from_trusted_xml, from_xml, #reverse_merge, #reverse_merge!, #slice!, #stringify_keys, #stringify_keys!, #symbolize_keys, #symbolize_keys!, #to_query, #to_xml, #transform_keys!, #transform_values!, #with_indifferent_access

Constructor Details

#initialize(attributes = nil) ⇒ 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">

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

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

Class Method Details

.const_missing(const_name) ⇒ Object


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# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 122

def self.const_missing(const_name)
  super unless const_name == :NEVER_UNPERMITTED_PARAMS
  ActiveSupport::Deprecation.warn(<<-MSG.squish)
    `ActionController::Parameters::NEVER_UNPERMITTED_PARAMS` has been deprecated.
    Use `ActionController::Parameters.always_permitted_parameters` instead.
  MSG

  always_permitted_parameters
end

Instance Method Details

#[](key) ⇒ Object

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

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# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 350

def [](key)
  convert_hashes_to_parameters(key, super)
end

#converted_arraysObject

Attribute that keeps track of converted arrays, if any, to avoid double looping in the common use case permit + mass-assignment. Defined in a method to instantiate it only if needed.

Testing membership still loops, but it's going to be faster than our own loop that converts values. Also, we are not going to build a new array object per fetch.


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# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 197

def converted_arrays
  @converted_arrays ||= Set.new
end

#delete(key, &block) ⇒ Object

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.


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# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 420

def delete(key, &block)
  convert_hashes_to_parameters(key, super, false)
end

#dupObject

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

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# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 437

def dup
  super.tap do |duplicate|
    duplicate.permitted = @permitted
  end
end

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

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


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# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 180

def each_pair(&block)
  super do |key, value|
    convert_hashes_to_parameters(key, value)
  end

  super
end

#extract!(*keys) ⇒ Object

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) # => {"a"=>1, "b"=>2}
params                  # => {"c"=>3}

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# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 387

def extract!(*keys)
  new_instance_with_inherited_permitted_status(super)
end

#fetch(key, *args) ⇒ Object

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"

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# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 365

def fetch(key, *args)
  convert_hashes_to_parameters(key, super, false)
rescue KeyError
  raise ActionController::ParameterMissing.new(key)
end

#permit(*filters) ⇒ Object

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"}}


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# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 327

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

#permit!Object

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">

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# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 223

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

#permitted?Boolean

Returns true if the parameter is permitted, false otherwise.

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

Returns:

  • (Boolean)

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# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 207

def permitted?
  @permitted
end

#require(key) ⇒ Object Also known as: required

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


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# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 246

def require(key)
  value = self[key]
  if value.present? || value == false
    value
  else
    raise ParameterMissing.new(key)
  end
end

#select!(&block) ⇒ Object

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


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# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 425

def select!(&block)
  convert_value_to_parameters(super)
end

#slice(*keys) ⇒ Object

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)     # => {}

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# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 378

def slice(*keys)
  new_instance_with_inherited_permitted_status(super)
end

#to_hObject

Returns a safe Hash representation of this parameter with all unpermitted keys removed.

params = ActionController::Parameters.new({
  name: 'Senjougahara Hitagi',
  oddity: 'Heavy stone crab'
})
params.to_h # => {}

safe_params = params.permit(:name)
safe_params.to_h # => {"name"=>"Senjougahara Hitagi"}

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# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 164

def to_h
  if permitted?
    to_hash
  else
    slice(*self.class.always_permitted_parameters).permit!.to_h
  end
end

#to_unsafe_hObject Also known as: to_unsafe_hash

Returns an unsafe, unfiltered Hash representation of this parameter.


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# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 173

def to_unsafe_h
  to_hash
end

#transform_keysObject

This method is here only to make sure that the returned object has the correct permitted status. It should not matter since the parent of this object is HashWithIndifferentAccess


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# File 'actionpack/lib/action_controller/metal/strong_parameters.rb', line 408

def transform_keys # :nodoc:
  if block_given?
    new_instance_with_inherited_permitted_status(super)
  else
    super
  end
end

#transform_valuesObject

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 }# => {"a"=>2, "b"=>4, "c"=>6}


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

def transform_values
  if block_given?
    new_instance_with_inherited_permitted_status(super)
  else
    super
  end
end