Class: ActionController::Parameters

By default, never raise an UnpermittedParameters exception if these params are present. The default includes both 'controller' and 'action' because they are added by ::Rails and should be of no concern. One way to change these is to specify always_permitted_parameters in your config. For instance:

config.always_permitted_parameters = %w( controller action format )

Returns true if the parameter is permitted, false otherwise.

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

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.

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.

Returns an exact copy of the 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

Alias for #each_pair.

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

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}

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 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"

Returns a new 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: 'none@test.com',
      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"=>"none@test.com", "phone"=>"555-1234"}}

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">

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

Alias for #require.

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

Returns a new 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)     # => {}

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"}

Returns an unsafe, unfiltered ::Hash representation of this parameter.

Alias for #to_unsafe_h.

Returns a new 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}