Question

Want to be able to provide a search interface for a collection of objects to be used by passing a list of keyword arguments like so:

playerID = players.search(nameFirst='ichiro', nameLast='suzuki')

Where players.search is defined like so:

def search(self, **args):
    ret = []
    for playerID, player in self.iteritems():
        for key, value in args.iteritems():
            if getattr(player, key) == value:
                ret.append(player.playerID)

    return ret

Obviously the above code doesn’t work. I want to, to borrow some SQL idioms, to work like where player.key == value and player.keyN = valueN, and so on for N number of kwargs passed.

Any ideas? Thanks!

Answer 1

I want to, to borrow some SQL idioms,
to work like where player.key == value
and player.keyN = valueN, and so on
for N number of kwargs passed.

So you’re currently implementing an OR and want to implement an AND instead — is that it?

If so, then the all suggested in @Mark’s answer would work — or alternatively, and equivalently albeit at a lower level of abstraction:

def search(self, **args):
  ret = []
  for playerID, player in self.iteritems():
    for key, value in args.iteritems():
      if getattr(player, key) != value: break
    else:
       ret.append(player.playerID)

  return ret

I’m not quite sure why you’re looping on iteritems and then ignoring the key you’re getting (appending player.playerID rather than the playerID key directly).

Anyway, another high-abstraction approach, assuming you don’t need the keys…:

def search(self, **args):
  def vals(p):
    return dict((k, getattr(p, k, None)) for k in args)
  return [p.playerID for p in self.itervalues() if vals(p) == args]

This one doesn’t “short-circuit” but is otherwise equivalent to Mark’s. Fully equivalent, but quite concise:

def search(self, **args):
  return [p.playerID for p in self.itervalues()
          if all(getattr(p, k, None)==args[k] for k in args)]

If these code snippets don’t meet your needs, and you can clarify why exactly they don’t (ideally with an example or three!-), I’m sure they can be tweaked to satisfy said needs.