Ruby Arrays: select(), collect(), and map()

Question

The syntax for mapping:

a = ["a", "b", "c", "d"]      #=> ["a", "b", "c", "d"]  a.map {|item|"a" == item}     #=> [true, false, false, false]  a.select {|item|"a" == item}  #=> ["a"] 

Question how about if I have:

 irb(main):105:0> details[1]  => {:sku=>"507772-B21", :desc=>"HP 1TB 3G SATA 7.2K RPM LFF (3 .", :qty=>"",   :qty2=>"1", :price=>"5,204.34 P"} 

I want to delete every entry which has an empty qty value on this array or select only the ones with some value in it.

I tried:

details.map {|item|"" == item} 

Just returns a lot of false and then when I use the same just change map to select I get:

[] 

Answer 1

It looks like details is an array of hashes. So item inside of your block will be the whole hash. Therefore, to check the :qty key, you'd do something like the following:

details.select{ |item| item[:qty] != "" } 

That will give you all items where the :qty key isn't an empty string.

official select documentation