build_conditions

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# Given a hash that's built from an HTML form, this little gadget
# will build an appropriate chunk of SQL to be used in a 
# :conditions => call.
#
# input is the hash we got from the form
# conjunction is whatever we stick between our conditions, 
# defaulting to AND name is the optional name for the left-hand side
# of the condition.  
#
# This is necessary for inner arrays.
def build_conditions(input, conjunction = "AND", name = nil)
  cond = ""
  values = []

  input.collect { |k,v|
    # Problem is, all forms come back with a key, but if the value
    # is blank, we want to move on
    next if v == ""

    # If there's already something in the conditions string, we 
    # need to tack on our conjunction.  We can't get into a 
    # position where the conjunction ends the string, since we 
    # output everything lower.
    cond << " #{conjunction} " unless cond.empty?

    if v.class == Array && v.size > 1
      ret = build_conditions(v, "OR", k)
      cond << "(#{ret})"
    else
      cond << "#{name.nil? ? k : name} = ?"
    end

    values << v
  }

  return [cond, values].flatten
end