There's a method
Integer()
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defined on Kernel, that typecasts everything into an Integer.
Integer("2") # 2
Integer("foo") # Invalid value for Integer() (ArgumentError)
Integer(nil) # Can't convert nil to Integer (TypeError)
Integer([]) # Can't convert Array into Integer (TypeError)
Integer(Object.new) # Can't convert Object into Integer (TypeError)
Integer(2) # 2
Integer("11", 2) # 3
This is very similar but not identical to to_i:
"2".to_i # 2
"foo".to_i # 0
nil.to_i # 0
[].to_i # undefined method 'to_i' for an instance of Array (NoMethodError)
Object.new.to_i # undefined method 'to_i' for an instance of Object (NoMethodError)
2.to_i # 2
"11".to_i(2) # 3
Integer() supports a exception: false variant, which is very handy to cast user input without any exception:
Integer("2", exception: false) # 2
Integer("foo", exception: false) # nil
Integer(nil, exception: false) # nil
Integer([], exception: false) # nil
Integer(Object.new, exception: false) # nil
Integer(2, exception: false) # 2
Integer("11", 2, exception: false) # 3
This is typically useful for casting a user defined parameter to an Integer without causing exception notifications:
# can cause exceptions
def show
# there's no guarantee that params[:page] is something that can be cast to an Integer
Record.paginate(page: params[:page])
end
# will not raise because of a failed typecast
def show
Record.paginate(page: Integer(params[:page], exception: false))
end
Alternative: Cast with ActiveModel
If you have ActiveModel you can also use the same casting rules of your ActiveRecord attributes:
ActiveModel::Type::Integer.new.cast("2") # 2
ActiveModel::Type::Integer.new.cast(nil) # nil
ActiveModel::Type::Integer.new.cast([]) # nil
ActiveModel::Type::Integer.new.cast(Object.new) # nil
ActiveModel::Type::Integer.new.cast(2) # 2
Similiar casting rules are available for other types, like ActiveModel::Type::Boolean or ActiveModel::Type::Date.
Posted by Niklas Hä. to makandra dev (2025-09-17 11:51)