datastore.get() requires a list

[jgeewax]

See http://googlecloudplatform.github.io/gcloud-python/

The snippet is:

from gcloud import datastore
datastore.set_defaults()

product_key = datastore.Key('Product', 123)
print datastore.get([product_key])

I'd expect it to be:

from gcloud import datastore
product_key = datastore.Key('Product', 123)
product = datastore.get(product_key)

[dhermes]

Sorry about that. The homepage source only lives in the gh-pages branch so my git grep for set_defaults() missed it.

As for datastore.get(key), the method only accepts one type: a list (of keys). When we were making these, we were noticing that half the code was special casing the input types and it just wasn't worth it for two brackets.

[jgeewax]

@dhermes : Did we have an issue for that to discuss? I really think it's worthwhile to do that... :(

[dhermes]

No specific issue to discuss. Came as part of adding get() / put() / delete() as per request from datastore team. (They are very nice to have. I'm happy we did it, it made the code much nice and informed the way we wrote Batch -> Transaction.)

I know Python is slow already, but for high-traffic apps, I cringe at adding a branch point into these methods every time they get called

if isinstance(entities, list):
    ...
else:
    ...

[jgeewax]

The latency we'd be introducing there would be nothing compared to the latency from wire time getting to and from datastore. Datastore's selling point isn't latency, it's availability and throughput.

I'm a huge fan of taking away the brackets....

[jgeewax]

Renaming the issue to reflect the remaining issue: .get only ever taking a list.

I really would like to add the following to our .get method:

def get(keys):
  if isinstances(keys, datastore.Key):
    keys = [keys]
  ...

I have no issue at all with the extra branch when this is called. Our goal is usability first, performance second.

[theacodes]

I would also prefer adding the ability to specify a single key and additionally not get a list back if I specify a single key.

[jgeewax]

Oh - that's a good point! We should recognize when a single key is provided and return a single result back. Maybe something along the lines of...

def get(key):
  if not isinstance(key, datastore.Key):
    return get_multi(key)
  result = get_multi([key])
  return result[0] if result else None

def get_multi(keys):
  return multiple_entity_results

[theacodes]

Yep, that's exactly what I had in mind.