Is it possible to have variable find conditions for both the key and value?

Question

I'm trying to pass in both the field and the value in a find call:

@employee = Employee.find(:all,
              :conditions => [ '? = ?', params[:key], params[:value].to_i)

The output is

SELECT * FROM `employees` WHERE ('is_manager' = 1)

Which returns no results, however when I try this directly in mysqsl using the same call without the '' around is_manager, it works fine. How do I convert my params[:key] value to a symbol so that the resulting SQL call looks like:

SELECT * FROM `employees` WHERE (is_manager = 1)

Thanks, D

Answer 1

If you want to convert a string to symbol(which is what params[:key] produces, all you need to do is

params[:key].to_s.to_sym

2 points:

1. A word of caution : symbols are not garbage collected.

2. Make sure your key is not a number, if you convert to_s first then to_sym, your code will work but you may get a wierd symbol like this:

   :"5"

Answer 2

"string".to_sym

Answer 3

You could use variable substitution for column name instead of using bind values:

# make sure the key passed is a valid column
if Employee.columns_hash[params[:key]]
  Employee.all :conditions => [ "#{params[:key]} = ?", params[:value]]
end

You can further secure the solution by ensuring column name passed belongs to a pre selected set.:

if ["first_name", "last_name"].include? [params[:key]]
  Employee.all :conditions => [ "#{params[:key]} = ?", params[:value]]
end