How to check if a param is true or false?

Question

This is really racking my brain, but maybe I'm trying to hard.

I'm passing a param via a URL (example.com?debug=true)

So I basically want to say:

if params[:debug] == true
 do xyz
else
 do abc
end

But for whatever reason that if statement just isn't doing like it seems like it should.

Is there a better way to do that if/else statement based on a param being true or false?

The debug param will either have a value of true, no value, or a value of false (as far as the URL goes).

Tabbitha

Answer 1

params come in as strings, so you need to compare against "true", not true.

Adriel

That was the problem...wasn't comparing as a string. – Tabbitha

another solution is to check for it's presence if params[:debug].present? – Footsore

@Avouch For nil and false the method .present? returns false. It is the exact opposite of .blank?. – Footsore

@Footsore the answer here says params come in as strings. If params[:debug] is the string "false" it will be present (i.e. evaluated incorrectly). – Avouch

@Avouch in that case, yes... I'm not sure if the parameter will ever come as "false" or will simply be omitted... – Footsore

Such a silly mistake. Was stuck on this for more than an hour. Thanks!! – Deliadelian

Answer 2

You could use ActiveRecord's method of checking truthful values if you don't want to reinvent the wheel (this is what is used when passing params inside an ActiveRecord object

Rails 3-4.1

if ActiveRecord::ConnectionAdapters::Column.value_to_boolean(params[:debug])
    do xyz
else
    do abc

Rails 4.2.0

ActiveRecord::Type::Boolean.new.type_cast_from_database(params[:debug])

Rails 5

ActiveModel::Type::Boolean.new.cast(params[:debug])

Might be worth wrapping in a helper but never the less it's quite flexible:

rails c
Loading development environment (Rails 3.2.6)
1.9.3p194 :001 > ActiveRecord::ConnectionAdapters::Column.value_to_boolean '1'
 => true 
1.9.3p194 :002 > ActiveRecord::ConnectionAdapters::Column.value_to_boolean '0'
 => false 
1.9.3p194 :003 > ActiveRecord::ConnectionAdapters::Column.value_to_boolean 1
 => true 
1.9.3p194 :004 > ActiveRecord::ConnectionAdapters::Column.value_to_boolean true
 => true 
1.9.3p194 :005 > ActiveRecord::ConnectionAdapters::Column.value_to_boolean 'true'
 => true 
1.9.3p194 :006 > ActiveRecord::ConnectionAdapters::Column.value_to_boolean 'on'
 => true 
1.9.3p194 :007 > ActiveRecord::ConnectionAdapters::Column.value_to_boolean 'off'

Custom extension

Some people frown on extending core classes but this does fit with the DRY principle.

# config/initializer/boolean.rb
class Boolean
  def self.parse(value)
    ActiveRecord::ConnectionAdapters::Column.value_to_boolean(value)
  end
end

Then used like

if Boolean.parse(params[:debug])
  then xyz

Situated

It seems that this is not part of the public api as of Rails 4: api.rubyonrails.org – Musette

Looks still there to me github.com/rails/rails/blob/… – Situated

Answer 3

Since Rails/ActiveRecord 4.2.0 it is

if ActiveRecord::Type::Boolean.new.type_cast_from_user params[:debug]
  do xyz
else
  do abc
end

In Rails 5 it is:

if ActiveModel::Type::Boolean.new.cast params[:debug]
  do xyz
else
  do abc
end

Moultrie

Answer 4

But for whatever reason that if statement just isn't doing like it seems like it should.

I can almost guarantee that it is doing exactly what it should. When things don't make sense, one of our assumptions is wrong.

Is the value actually a boolean or is it string (or something else?). If the value is a string then of course the comparison to the boolean value true will fail. Try comparing to 'true' and see if that works.

Natashianatassia

Contradictions do not exist. Whenever you think you are facing a contradiction, check your premises. You will find that one of them is wrong. (: – Kirchner

Answer 5

how about this?

params[:debug].to_s.downcase == 'true'

Ruppert