Trying to push results of hash to an array - Ruby on rails - ruby-on-rails

Question

I'm just beginning to (hopefully!) learn programming / ruby on rails and trying to push the results of a hash to an array using:
ApplicationController:
def css_class
css = Array.new
product = {#product.oil => ' oil', #product.pressure_meters => ' pressure_meters', #product.commercial => 'commercial'}
product.each do |key, value|
if key == true
css.push(value)
end
end
сss.join
end
And this in the ProductsController:
def create
#product = Product.new(params[:product])
#product.css_class = css_class
respond_to do |format|
if #product.save
format.html { redirect_to #product, notice: 'Product was successfully created.' }
format.json { render json: #product, status: :created, location: #product }
else
format.html { render action: "new" }
format.json { render json: #product.errors, status: :unprocessable_entity }
end
end
end
This only seems to only save the last thing that was pushed to the array, I tried the below code on it's own and it seems to work, so I'm baffled as to where I'm going wrong?
def css_class
css = Array.new
product = {1 => ' pressure_meters', 2 => ' oil'}
product.each do |key, value|
if key > 0
css.push(value)
end
end
css.join
end
puts css_class
Thanks in advance.

Answer 1

In Ruby Hash can't have duplicate keys so
def css_class
css = Array.new
product = { #product.oil => ' oil',
#product.pressure_meters => ' pressure_meters',
#product.commercial => 'commercial' }
product.each do |key, value|
if key == true
css.push(value)
end
end
сss.join
end
will not work because
irb(main):0> h = { true => 'foo', true => 'bar', false=>'foo', false => 'bar' }
=> {true=>"bar", false=>"bar"}
your second example works only because you have distinct keys (1,2) so let's refactor your code a bit
def css_class
css = ""
product = { ' oil' => #product.oil,
' pressure_meters' => #product.pressure_meters,
' commercial' => #product.commercial }
product.each do |key, value|
css << key if value
end
сss.strip
end
it can be simplified even more however previous version should work fine too
def css_class
[ "oil ", "pressure_meters ", "commercial " ].inject(""){ |sum, val| sum += val if #product.send( val.strip ) }.strip
end

Answer 2

You can use Hash#values to get an array of your hash's values.
So:
product_values = product.values
And conditionally, you could pick the ones you want using select, like this:
product_values = product.select {|k,v| k == true }.values
Which is verbose for:
product_values = product.select {|k,v| k }.values

Answer 3

Thanks for pointing me in the right direction. I kept getting a 500 internal server error with your code Bohdan, not sure why, but played around with it and eventually found this to work:
def css_class
css = Array.new
product = { ' oil' => #product.oil,
' pressure_meters' => #product.pressure_meters,
' commercial' => #product.commercial }
product.each do |key, value|
css << key if value
end
css.join
end