What is `params.require(:person).permit(:name, :age)` doing in Rails 4?
The params
in a controller looks like a Hash, but it's actually an instance of ActionController::Parameters
, which provides several methods such as require
and permit
.
The require
method ensures that a specific parameter is present, and if it's not provided, the require
method throws an error. It returns an instance of ActionController::Parameters
for the key passed into require
.
The permit
method returns a copy of the parameters object, returning only the permitted keys and values. When creating a new ActiveRecord model, only the permitted attributes are passed into the model.
It looks a lot like the whitelisting that was formerly included in ActiveRecord models, but it makes more sense for it to be in the controller.
To be more precise, when you create for eg. doing .new(...)
, there must be :person
hash indicated by require and the person hash will only accept :name
and :age
indicated by permit.
Example:
.new(person: { name: "Bhojendra", age: 32 }) // okay
.new(person: { name: "Rauniyar" }) // okay
.new(person: { name: "Bhojendra", other: 'asdf' }) // not okay, other not permitted
.new(person: { full_name: "Bhojendra Rauniyar" }) // not okay, full_name not permitted
.new(detail: { name: "Bhojendra", age: 32 }) // not okay, must be person