stronger_parameters
This is an extension of strong_parameters with added type checking and conversion.
Simple types
You can specify simple types like this:
params.permit(
id: Parameters.id,
name: Parameters.string
)
Arrays
You can specify arrays like this:
params.permit(
id: Parameters.array(Parameters.id)
)
This will allow an array of id parameters that all are IDs (integer less than 2**31, greater than 0) and convert to Fixnum ('2' --> 2).
Empty array -> nil
Rails converts empty arrays to nil unless config.action_dispatch.perform_deep_munge = false is set
(available in Rails 4.1+). Either use this or Parameters.array | Parameters.nil to deal with this.
Allowing nils
It can be convenient to allow nil to be passed as all kinds of attributes since ActiveRecord converts it to false/0 behind the scenes.
ActionController::Parameters.allow_nil_for_everything = true
Nested Parameters
params.permit(
name: Parameters.string,
emails: Parameters.array(Parameters.string),
friends: Parameters.array(
Parameters.map(
name: Parameters.string,
family: Parameters.map(
name: Parameters.string
)
hobbies: Parameters.array(Parameters.string)
)
)
)
This will allow parameters like this:
{
"name": "Mick",
"emails": ["[email protected]", "[email protected]"],
"friends": [
{"name": "Morten", "family": {"name": "Primdahl"}, "hobbies": ["work", "art"]},
{"name": "Eric", "family": {"name": "Chapweske"}, "hobbies": ["boating", "whiskey"]}
]
}
ActiveModel Nested Attributes
params.require(:author).permit(
name: Parameters.string,
books_attributes: Parameters.array(
Parameters.map(
title: Parameters.string,
id: Parameters.id,
_destroy: Parameters.boolean
)
)
)
This will allow parameters like this:
{
"author": {
"name": "Eric Chapweske",
"books_attributes": [
{"title": "Boatin' and Drinkin'", "id": 234, "_destroy": true},
{"title": "Advanced Boatin' and Drinkin'", "id": 567}
]
}
}
Combining Requirements
If you want to permit a parameter to be one of multiple types, you can use the | operator:
params.require(:ticket).permit(
status: Parameters.id | Parameters.enum('open', 'closed')
)
This will allow these parameter sets:
{
"ticket": {
"status": 123
}
}
{
"ticket": {
"status": "open"
}
}
You can use the & operator to apply further restrictions on the type:
params.require(:user).permit(
age: Parameters.integer & Parameters.gte(0)
)
This requires the parameter to be an integer greater than or equal to 0.
Combining Requirements in Arrays
You can also use the | and & operators in arrays:
params.require(:group).permit(
users: Parameters.array(Parameters.id | Parameters.string)
)
This will permit these parameters:
{
"group": {
"users": [123, "[email protected]", 345, 676, "[email protected]"]
}
}
Production rollout
Just want to log violations in production:
# config/environments/production.rb
ActionController::Parameters.action_on_invalid_parameters = :log
Types
| Syntax | (Simplified) Definition |
|---|---|
| Parameters.string | value.is_a?(String) |
| Parameters.integer | value.is_a?(Fixnum) or '-1' |
| Parameters.float | value.is_a?(Float) or '-1.2' |
| Parameters.datetime | value.is_a?(DateTime) or '2014-05-13' or '2015-03-31T14:34:56Z' |
| Parameters.regexp(/foo/) | value =~ regexp |
| Parameters.enum('asc', 'desc') | ['asc', 'desc'].include?(value) |
| Parameters.lt(10) | value < 10 |
| Parameters.lte(10) | value <= 10 |
| Parameters.gt(0) | value > 0 |
| Parameters.gte(0) | value >= 0 |
| Parameters.integer32 | Parameters.integer & Parameters.lt(2 ** 31) & Parameters.gte(-2 ** 31) |
| Parameters.integer64 | Parameters.integer & Parameters.lt(2 ** 63) & Parameters.gte(-2 ** 63) |
| Parameters.id | Parameters.integer & Parameters.lt(2 ** 31) & Parameters.gte(0) |
| Parameters.bigid | Parameters.integer & Parameters.lt(2 ** 63) & Parameters.gte(0) |
| Parameters.uid | Parameters.integer & Parameters.lt(2 ** 32) & Parameters.gte(0) |
| Parameters.ubigid | Parameters.integer & Parameters.lt(2 ** 64) & Parameters.gte(0) |
| Parameters.boolean | Parameters.enum(true, false, 'true', 'false', 1, 0) |
| Parameters.nil | value is nil |
| Parameters.nil_string | value is nil, '', 'undefined' |
| Parameters.file | File, StringIO, Rack::Test::UploadedFile, ActionDispatch::Http::UploadedFile or subclasses |
| Parameters.decimal(8,2) | value is a String, Integer or Float with a precision of 8 and scale of 2 |