Action ControllerParameters¶↑
Allows you to choose which attributes should be permitted for mass updating and thus prevent accidentally exposing that which shouldn’t be exposed.
Provides methods for filtering and requiring params:
expectto safely permit and require parameters in one step.permitto filter params for mass assignment.requireto require a parameter or raise an error.
Examples:
params =ActionController::Parameters.new({person: {name:"Francesco",age:22,role:"admin" }})permitted =params.expect(person: [:name,:age])permitted# => #<ActionController::Parameters {"name"=>"Francesco", "age"=>22} permitted: true>Person.first.update!(permitted)# => #<Person id: 1, name: "Francesco", age: 22, role: "user">
Parameters provides two options that control the top-level behavior of new instances:
permit_all_parameters- If it’strue, all the parameters will be permitted by default. The default isfalse.action_on_unpermitted_parameters- Controls behavior when parameters that are not explicitly permitted are found. The default value is:login test and development environments,falseotherwise. The values can be:falseto take no action.:logto emit anActiveSupport::Notifications.instrumentevent on theunpermitted_parameters.action_controllertopic and log at the DEBUG level.:raiseto raise anActionController::UnpermittedParametersexception.
Examples:
params =ActionController::Parameters.newparams.permitted?# => falseActionController::Parameters.permit_all_parameters =trueparams =ActionController::Parameters.newparams.permitted?# => trueparams =ActionController::Parameters.new(a:"123",b:"456")params.permit(:c)# => #<ActionController::Parameters {} permitted: true>ActionController::Parameters.action_on_unpermitted_parameters =:raiseparams =ActionController::Parameters.new(a:"123",b:"456")params.permit(:c)# => ActionController::UnpermittedParameters: found unpermitted keys: a, b
Please note that these optionsare not thread-safe. In a multi-threaded environment they should only be set once at boot-time and never mutated at runtime.
You can fetch values ofActionController::Parameters using either:key or"key".
params =ActionController::Parameters.new(key:"value")params[:key]# => "value"params["key"]# => "value"
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Constants
| PERMITTED_SCALAR_TYPES | = | [String,Symbol,NilClass,Numeric,TrueClass,FalseClass,Date,Time,# DateTimes are Dates, we document the type but avoid the redundant check.StringIO,IO,ActionDispatch::Http::UploadedFile,Rack::Test::UploadedFile,] |
This is a list of permitted scalar types that includes the ones supported in XML and JSON requests. This list is in particular used to filter ordinary requests, If you modify this collection please update the one in the | ||
Attributes
| [R] | parameters | |
| [W] | permitted |
Class Public methods
new(parameters = {}, logging_context = {})Link
Returns a newActionController::Parameters instance. Also, sets thepermitted attribute to the default value ofActionController::Parameters.permit_all_parameters.
classPerson<ActiveRecord::Baseendparams =ActionController::Parameters.new(name:"Francesco")params.permitted?# => falsePerson.new(params)# => ActiveModel::ForbiddenAttributesErrorActionController::Parameters.permit_all_parameters =trueparams =ActionController::Parameters.new(name:"Francesco")params.permitted?# => truePerson.new(params)# => #<Person id: nil, name: "Francesco">
# File actionpack/lib/action_controller/metal/strong_parameters.rb, line 287definitialize(parameters = {},logging_context = {})parameters.each_keydo|key|unlesskey.is_a?(String)||key.is_a?(Symbol)raiseInvalidParameterKey,"all keys must be Strings or Symbols, got: #{key.class}"endend@parameters =parameters.with_indifferent_access@logging_context =logging_context@permitted =self.class.permit_all_parametersend
Instance Public methods
==(other)Link
Returns true if anotherParameters object contains the same content and permitted flag.
[](key)Link
Returns a parameter for the givenkey. If not found, returnsnil.
params =ActionController::Parameters.new(person: {name:"Francesco" })params[:person]# => #<ActionController::Parameters {"name"=>"Francesco"} permitted: false>params[:none]# => nil
[]=(key, value)Link
Assigns a value to a givenkey. The given key may still get filtered out whenpermit is called.
as_json(options=nil)Link
Returns a hash that can be used as the JSON representation for the parameters.
Source:on GitHub
# File actionpack/lib/action_controller/metal/strong_parameters.rb, line 194compact()Link
Returns a newActionController::Parameters instance withnil values removed.
compact!()Link
Removes allnil values in place and returnsself, ornil if no changes were made.
compact_blank()Link
Returns a newActionController::Parameters instance without the blank values. UsesObject#blank? for determining if a value is blank.
compact_blank!()Link
Removes all blank values in place and returns self. UsesObject#blank? for determining if a value is blank.
converted_arrays()Link
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.
deep_dup()Link
Returns a duplicateActionController::Parameters instance with the same permitted parameters.
deep_merge(other_hash, &block)Link
Returns a newActionController::Parameters instance withself andother_hash merged recursively.
Like withHash#merge in the standard library, a block can be provided to merge values.
Source:on GitHub
# File actionpack/lib/action_controller/metal/strong_parameters.rb, line 168deep_merge!(other_hash, &block)Link
Same asdeep_merge, but modifiesself.
Source:on GitHub
# File actionpack/lib/action_controller/metal/strong_parameters.rb, line 183deep_transform_keys(&block)Link
Returns a newActionController::Parameters instance with the results of runningblock once for every key. This includes the keys from the root hash and from all nested hashes and arrays. The values are unchanged.
deep_transform_keys!(&block)Link
Returns the sameActionController::Parameters instance with changed keys. This includes the keys from the root hash and from all nested hashes and arrays. The values are unchanged.
delete(key, &block)Link
Deletes a key-value pair fromParameters and returns the value. Ifkey is not found, returnsnil (or, with optional code block, yieldskey and returns the result). This method is similar toextract!, which returns the correspondingActionController::Parameters object.
dig(*keys)Link
Extracts the nested parameter from the givenkeys by callingdig at each step. Returnsnil if any intermediate step isnil.
params =ActionController::Parameters.new(foo: {bar: {baz:1 } })params.dig(:foo,:bar,:baz)# => 1params.dig(:foo,:zot,:xyz)# => nilparams2 =ActionController::Parameters.new(foo: [10,11,12])params2.dig(:foo,1)# => 11
each_key(&block)Link
Calls block once for each key in the parameters, passing the key. If no block is given, an enumerator is returned instead.
Source:on GitHub
# File actionpack/lib/action_controller/metal/strong_parameters.rb, line 202each_pair(&block)Link
Convert all hashes in values into parameters, then yield each pair in the same way asHash#each_pair.
each_value(&block)Link
Convert all hashes in values into parameters, then yield each value in the same way asHash#each_value.
empty?()Link
Returns true if the parameters have no key/value pairs.
Source:on GitHub
# File actionpack/lib/action_controller/metal/strong_parameters.rb, line 211eql?(other)Link
except(*keys)Link
Returns a newActionController::Parameters instance that filters out the givenkeys.
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>
exclude?(key)Link
Returns true if the given key is not present in the parameters.
Source:on GitHub
# File actionpack/lib/action_controller/metal/strong_parameters.rb, line 219expect(*filters)Link
expect is the preferred way to require and permit parameters. It is safer than the previous recommendation to callpermit andrequire in sequence, which could allow user triggered 500 errors.
expect is more strict with types to avoid a number of potential pitfalls that may be encountered with the.require.permit pattern.
For example:
params =ActionController::Parameters.new(comment: {text:"hello" })params.expect(comment: [:text])# => #<ActionController::Parameters { text: "hello" } permitted: true>params =ActionController::Parameters.new(comment: [{text:"hello" }, {text:"world" }])params.expect(comment: [:text])# => ActionController::ParameterMissing: param is missing or the value is empty or invalid: comment
In order to permit an array of parameters, the array must be defined explicitly. Use double array brackets, an array inside an array, to declare that an array of parameters is expected.
params =ActionController::Parameters.new(comments: [{text:"hello" }, {text:"world" }])params.expect(comments: [[:text]])# => [#<ActionController::Parameters { "text" => "hello" } permitted: true>,# #<ActionController::Parameters { "text" => "world" } permitted: true>]params =ActionController::Parameters.new(comments: {text:"hello" })params.expect(comments: [[:text]])# => ActionController::ParameterMissing: param is missing or the value is empty or invalid: comments
expect is intended to protect against array tampering.
params =ActionController::Parameters.new(user:"hack")# The previous way of requiring and permitting parameters will errorparams.require(:user).permit(:name,pets: [:name])# wrong# => NoMethodError: undefined method `permit' for an instance of String# similarly with nested parametersparams =ActionController::Parameters.new(user: {name:"Martin",pets: {name:"hack" } })user_params =params.require(:user).permit(:name,pets: [:name])# wrong# user_params[:pets] is expected to be an array but is a hash
expect solves this by being more strict with types.
params =ActionController::Parameters.new(user:"hack")params.expect(user: [:name,pets: [[:name]] ])# => ActionController::ParameterMissing: param is missing or the value is empty or invalid: user# with nested parametersparams =ActionController::Parameters.new(user: {name:"Martin",pets: {name:"hack" } })user_params =params.expect(user: [:name,pets: [[:name]] ])user_params[:pets]# => nil
As the examples show,expect requires the:user key, and any root keys similar to the.require.permit pattern. If multiple root keys are expected, they will all be required.
params =ActionController::Parameters.new(name:"Martin",pies: [{type:"dessert",flavor:"pumpkin"}])name,pies =params.expect(:name,pies: [[:type,:flavor]])name# => "Martin"pies# => [#<ActionController::Parameters {"type"=>"dessert", "flavor"=>"pumpkin"} permitted: true>]
When called with a hash with multiple keys,expect will permit the parameters and require the keys in the order they are given in the hash, returning an array of the permitted parameters.
params =ActionController::Parameters.new(subject: {name:"Martin" },object: {pie:"pumpkin" })subject,object =params.expect(subject: [:name],object: [:pie])subject# => #<ActionController::Parameters {"name"=>"Martin"} permitted: true>object# => #<ActionController::Parameters {"pie"=>"pumpkin"} permitted: true>
Besides being more strict about array vs hash params,expect uses permit internally, so it will behave similarly.
params =ActionController::Parameters.new({person: {name:"Francesco",age:22,pets: [{name:"Purplish",category:"dogs" }] }})permitted =params.expect(person: [:name, {pets: [[:name]] } ])permitted.permitted?# => truepermitted[:name]# => "Francesco"permitted[:age]# => nilpermitted[:pets][0][:name]# => "Purplish"permitted[:pets][0][:category]# => nil
An array of permitted scalars may be expected with the following:
params =ActionController::Parameters.new(tags: ["rails","parameters"])permitted =params.expect(tags: [])permitted# => ["rails", "parameters"]permitted.is_a?(Array)# => truepermitted.size# => 2
expect!(*filters)Link
Same asexpect, but raises anActionController::ExpectedParameterMissing instead ofActionController::ParameterMissing. Unlikeexpect which will render a 400 response,expect! will raise an exception that is not handled. This is intended for debugging invalid params for an internalAPI where incorrectly formatted params would indicate a bug in a client library that should be fixed.
extract!(*keys)Link
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>
extract_value(key, delimiter: "_")Link
Returns parameter value for the givenkey separated bydelimiter.
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 givenkey‘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"]
fetch(key, *args)Link
Returns a parameter for the givenkey. If thekey can’t be found, there are several options: With no other arguments, it will raise anActionController::ParameterMissing error; if a second argument is given, then that is returned (converted to an instance ofActionController::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 or invalid: noneparams.fetch(:none, {})# => #<ActionController::Parameters {} permitted: false>params.fetch(:none,"Francesco")# => "Francesco"params.fetch(:none) {"Francesco" }# => "Francesco"
has_value?(value)Link
Returns true if the given value is present for some key in the parameters.
hash()Link
include?(key)Link
Returns true if the given key is present in the parameters.
Source:on GitHub
# File actionpack/lib/action_controller/metal/strong_parameters.rb, line 227inspect()Link
keys()Link
Returns a new array of the keys of the parameters.
Source:on GitHub
# File actionpack/lib/action_controller/metal/strong_parameters.rb, line 235merge(other_hash)Link
Returns a newActionController::Parameters instance with all keys fromother_hash merged into current hash.
merge!(other_hash)Link
Returns the currentActionController::Parameters instance withother_hash merged into current hash.
permit(*filters)Link
Returns a newActionController::Parameters instance that includes only the givenfilters and sets thepermitted attribute for the object totrue. This is useful for limiting which attributes should be allowed for mass updating.
params =ActionController::Parameters.new(name:"Francesco",age:22,role:"admin")permitted =params.permit(:name,:age)permitted.permitted?# => truepermitted.has_key?(:name)# => truepermitted.has_key?(:age)# => truepermitted.has_key?(:role)# => false
Only permitted scalars pass the filter. For example, given
params.permit(:name)
:name passes if it is a key ofparams whose associated value is of typeString,Symbol,NilClass,Numeric,TrueClass,FalseClass,Date,Time,DateTime,StringIO,IO,ActionDispatch::Http::UploadedFile orRack::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 usepermit on nested parameters:
params =ActionController::Parameters.new({person: {name:"Francesco",age:22,pets: [{name:"Purplish",category:"dogs" }] }})permitted =params.permit(person: [:name, {pets::name } ])permitted.permitted?# => truepermitted[:person][:name]# => "Francesco"permitted[:person][:age]# => nilpermitted[:person][:pets][0][:name]# => "Purplish"permitted[:person][:pets][0][:category]# => nil
This has the added benefit of rejecting user-modified inputs that send a string when a hash is expected.
When followed byrequire, you can both filter and require parameters following the typical pattern of aRails form. Theexpect method was made specifically for this use case and is the recommended way to require and permit parameters.
permitted =params.expect(person: [:name,:age])
When usingpermit andrequire separately, pay careful attention to the order of the method calls.
params =ActionController::Parameters.new(person: {name:"Martin",age:40,role:"admin" })permitted =params.permit(person: [:name,:age]).require(:person)# correct
When require is used first, it is possible for users of your application to trigger a NoMethodError when the user, for example, sends a string for :person.
params =ActionController::Parameters.new(person:"tampered")permitted =params.require(:person).permit(:name,:age)# not recommended# => NoMethodError: undefined method `permit' for an instance of String
Note that if you usepermit 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.permit(person::contact).require(:person)# => ActionController::ParameterMissing: param is missing or the value is empty or invalid: personparams.permit(person: {contact::phone }).require(:person)# => #<ActionController::Parameters {"contact"=>#<ActionController::Parameters {"phone"=>"555-1234"} permitted: true>} permitted: true>params.permit(person: {contact: [:email,:phone ] }).require(:person)# => #<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"}}}
permit!()Link
Sets thepermitted attribute totrue. This can be used to pass mass assignment. Returnsself.
classPerson<ActiveRecord::Baseendparams =ActionController::Parameters.new(name:"Francesco")params.permitted?# => falsePerson.new(params)# => ActiveModel::ForbiddenAttributesErrorparams.permit!params.permitted?# => truePerson.new(params)# => #<Person id: nil, name: "Francesco">
permitted?()Link
Returnstrue if the parameter is permitted,false otherwise.
params =ActionController::Parameters.newparams.permitted?# => falseparams.permit!params.permitted?# => true
reject(&block)Link
Returns a newActionController::Parameters instance with items that the block evaluates to true removed.
reject!(&block)Link
Removes items that the block evaluates to true and returns self.
require(key)Link
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 singletonfalse, returns said value:
ActionController::Parameters.new(person: {name:"Francesco" }).require(:person)# => #<ActionController::Parameters {"name"=>"Francesco"} permitted: false>
Otherwise raisesActionController::ParameterMissing:
ActionController::Parameters.new.require(:person)# ActionController::ParameterMissing: param is missing or the value is empty or invalid: personActionController::Parameters.new(person:nil).require(:person)# ActionController::ParameterMissing: param is missing or the value is empty or invalid: personActionController::Parameters.new(person:"\t").require(:person)# ActionController::ParameterMissing: param is missing or the value is empty or invalid: personActionController::Parameters.new(person: {}).require(:person)# ActionController::ParameterMissing: param is missing or the value is empty or invalid: 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 or invalid: user
This method is not recommended for fetching terminal values because it does not permit the values. For example, this can cause problems:
# CAREFULparams =ActionController::Parameters.new(person: {name:"Finn" })name =params.require(:person).require(:name)# CAREFUL
It is recommended to useexpect instead:
defperson_paramsparams.expect(person::name).require(:name)end
reverse_merge(other_hash)Link
Returns a newActionController::Parameters instance with all keys from current hash merged intoother_hash.
reverse_merge!(other_hash)Link
Returns the currentActionController::Parameters instance with current hash merged intoother_hash.
select(&block)Link
Returns a newActionController::Parameters instance with only items that the block evaluates to true.
select!(&block)Link
Equivalent to Hash#keep_if, but returnsnil if no changes were made.
slice(*keys)Link
Returns a newActionController::Parameters instance that includes only the givenkeys. If the givenkeys 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>
slice!(*keys)Link
Returns the currentActionController::Parameters instance which contains only the givenkeys.
to_h(&block)Link
Returns a safeActiveSupport::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 hashsafe_params =params.permit(:name)safe_params.to_h# => {"name"=>"Senjougahara Hitagi"}
to_hash()Link
Returns a safeHash 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 hashsafe_params =params.permit(:name)safe_params.to_hash# => {"name"=>"Senjougahara Hitagi"}
to_query(*args)Link
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 hashsafe_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.
to_s()Link
Returns the content of the parameters as a string.
to_unsafe_h()Link
Returns an unsafe, unfilteredActiveSupport::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"}
to_unsafe_hash()Link
transform_keys(&block)Link
Returns a newActionController::Parameters instance with the results of runningblock once for every key. The values are unchanged.
transform_keys!(&block)Link
Performs keys transformation and returns the alteredActionController::Parameters instance.
transform_values()Link
Returns a newActionController::Parameters instance with the results of runningblock 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>
transform_values!()Link
Performs values transformation and returns the alteredActionController::Parameters instance.
value?(value)Link
values()Link
Returns a new array of the values of the parameters.
values_at(*keys)Link
Returns values that were assigned to the givenkeys. Note that all theHash objects will be converted toActionController::Parameters.
with_defaults(other_hash)Link
with_defaults!(other_hash)Link
Instance Protected methods
each_nested_attribute()Link
nested_attributes?()Link
permit_filters(filters, on_unpermitted: nil, explicit_arrays: true)Link
Filters self and optionally checks for unpermitted keys
# File actionpack/lib/action_controller/metal/strong_parameters.rb, line 1130defpermit_filters(filters,on_unpermitted:nil,explicit_arrays:true)params =self.class.newfilters.flatten.eachdo|filter|casefilterwhenSymbol,String# Declaration [:name, "age"]permitted_scalar_filter(params,filter)whenHash# Declaration [{ person: ... }]hash_filter(params,filter,on_unpermitted:,explicit_arrays:)endendunpermitted_parameters!(params,on_unpermitted:)params.permit!end