One SELECT, multiple sorts

rubyonrails-talk
1

I want to pull data from the database once, but do multiple sorts on different columns.

I'm pulling a list of products from the database. In my view, I want to create two select lists: one sorted by the product name; one sorted by part number. I know I can map the values into a new array or use "options_from_collection_for_select," but I'm having a little trouble with sorting.

products.map { |p| [p.id, p.name] }.sort

=> [[7, "DataCollector"], [8, "DataTranslator"], [9, "DataMonitor"], [10, "DataExpress"], [11, "DataView"]]

The "sort" command sorts by the first item in each array, as can be seen by switching the values:

products.map { |p| [p.name, p.id] }.sort

=> [["DataCollector", 7], ["DataExpress", 10], ["DataMonitor", 9], ["DataTranslator", 8], ["DataView", 11]]

So, how do I get the sort order I want from the second example, but keep the structure from the first example so the select list will display correctly?

Thanks.

2

products.sort_by{|p| p.name}.map{|p| [p.name, p.id}

is one way.

-philip

3

I want to pull data from the database once, but do multiple sorts on different columns.

I'm pulling a list of products from the database. In my view, I want to create two select lists: one sorted by the product name; one sorted by part number. I know I can map the values into a new array or use "options_from_collection_for_select," but I'm having a little trouble with sorting.

>> products.map { |p| [p.id, p.name] }.sort

sort takes a block - you can make it compare anyway you want with that block, eg [1,2,3].sort {|x,y| x <=> y} is the same as [1,2,3] but [1,2,3].sort {|x,y| y <=> x } would sort in opposite order and [1,2,3,4,5,6,7,8].sort {|x,y| (x%5) <=> (y%5)} sorts according to residue mod 5.

Fred

4

This works, too:

<%= select_tag('product[name]', options_for_select(@products.map { |p| [p.name, p.id] }.sort)) %>

Thanks, guys.