Parameter maximum value

[CharlesP]

When adding a parameter (i.e. per_page), is there a way to set the maximum value?

The cleanest (only) way I've found so far is to pass the entire array of possible options:
optional :per_page, values: [*1..100], default: 10, type: Integer

Is there a better way to achieve this?

[dblock]

I'll label this as a feature request to support min and max, obviously there be dragons for non enumerable types ;)

[jlfaber]

#1568 added a new feature to the ValuesValidator that allows a Proc to be supplied for anonymous custom validations. Using this, your example above might look like this.

optional :per_page, values: { proc: ->(v) { v.positive? && v <= 100 } }, default: 10, type: Integer

I should note that the ValuesValidator already accepted Ranges, so you also could have done this.

optional :per_page, values: 1..100, default: 10, type: Integer

For both your original example and my Range alternative, the validator will call include? on the passed value. And, in both cases, that could result in up to 100 individual tests as it enumerates the Array or Range to determine whether the supplied value is a member. This is probably not catastrophic with a relatively small Range, but doing something like 0..1000000 could cause some performance problems.

A way to avoid this is (again) to use proc to test using cover? instead of include?, which will instead check that the value is between the endpoints of the range.

optional :per_page, values: { proc: ->(v) { (1..100).cover? v } }, default: 10, type: Integer

[dblock]

Should we close this?

[CharlesP]

@jlfaber Thanks, that's a big help.

@dblock Yes, this looks like a valid workflow for this.