How can I get the ndb.Model when my only input is an ndb.Query?

问题

Let's say there is ndb.Model that looks like this:

class Foo(ndb.Model):
  bar = ndb.StringProperty()

My question is, if my only input is the Foo.query() how can I get the model as an object that this query belongs to?

def query_to_model(query):
  # some magic 
  return model

---

The Foo.query().kind return the model's name as a string, but I didn't manage to find a way to get it as an object.

The following works using eval, but only when the model is defined in the same file:

def query_to_model(query):
  return eval(query.kind)

I want something more general than that.

回答1:

After you have imported code with this model definition, the list ndb.Model._kind_map should contain it. Here is the magic:

def query_to_model(query):
  return ndb.Model._kind_map[query.name]

回答2:

I use this code to find the model class if you have the kind name:

model_module = KIND_MODULES(kind_name)
mod = __import__(model_module, globals(), locals(), [kind_name], -1)
model_class = getattr(mod, kind_name)

The KIND Modules dict holds the modules to import the models from:

KIND_MODULES = { 'Users' : 'models', 'Comments' : 'models', 'Cities' : 'examples.models' }

来源：https://stackoverflow.com/questions/14651975/how-can-i-get-the-ndb-model-when-my-only-input-is-an-ndb-query