from lotan import Lotan
from lotan.models import Model, IntField, StringField

# Define models
class Question(models.Model):

    id = models.IntField(is_key=True)
    title = models.StringField()
    member_id = models.IntField()

    def resolve_by_id(self):
        return {
            'title': 'This is title string',
            'member_id': 1,
        }

q = Question(id=1)

assert q.title == 'This is title string'
assert q.member_id == 1

Fields are mostly lazy loaded and resolved by resolve funcitons.

Note that not every non-key-field need a corresponding resolve funciton. the result returned by resolve_by_ functions will be automatically applied to model's fields, which means if the resolve_by_id function in the above example return a dict which contains gender data, the gender field of the Member instance will be set to it automatically event if there is no funciton named resolve_gender.

test_member.py

def test_init_by_id(self, rpc_member):
        rpc_member.get_member.return_value = FAKE_MEMBER
        member = Member(id=FAKE_MEMBER.id)
        self.assertEqual(member.id, FAKE_MEMBER.id)
        self.assertEqual(member.fullname, FAKE_MEMBER.fullname)
        rpc_member.get_member.assert_called_once_with(member_id=FAKE_MEMBER.id)

Lotan

base.py

__init__(self, **kwargs) 接收到了 kwargs = {'id' : 1} , 使用 _extract_seed_key(kwargs) 将 'id' 另存为 seed_key;

1. __eq__() calls run_key_resolver()

2. run_key_resolver() runs the key resolver

   • update _exist_state 的值 RAN_EXIST;
   • 得到有关于 key (id) 的 resolver, seed_key_resolver = self.get_key_resolver(self.seed_key)
seed_key_resolver = getattr(self, 'resolve_by_%s' % key_name, None)
   • 通过 query.py中的 ResolverManager 运行 resolve_by_key

   returned_key_result = self.resolver_manager.retrieve_field(
           key_name=self.seed_key,
           key_value=self.seed_value,
           field_name=self.seed_key,
           field_resolver=seed_key_resolver,
           session=self.session
   )
   

   • dispatch_key_result()
   • set_field_value()

3. retrieve_field() calls run_resolver(field_resolver)

   • 获取函数对象的arg。

     return self.run_resolver(
               field_resolver,
               *resolver_args,
               session=session
     )
   

   • run_resolver() : All resolver should call this to solve the problem.