Use py36 async generators for simplicity

Author: grigi

tortoise/fields.py

@@ -10,7 +10,6 @@
 from pypika import Table
 
 from tortoise.exceptions import ConfigurationError, NoValuesFetched, OperationalError
-from tortoise.utils import QueryAsyncIterator
 
 if TYPE_CHECKING:  # pragma: nocoverage
     from tortoise.models import Model
@@ -533,12 +532,13 @@ def __getitem__(self, item):
     def __await__(self):
         return self._query.__await__()
 
-    def __aiter__(self) -> QueryAsyncIterator:
-        async def fetched_callback(iterator_wrapper):
+    async def __aiter__(self):
+        if not self._fetched:
+            self.related_objects = await self
             self._fetched = True
-            self.related_objects = iterator_wrapper.sequence
 
-        return QueryAsyncIterator(self._query, callback=fetched_callback)
+        for val in self.related_objects:
+            yield val
 
     def filter(self, *args, **kwargs):
         """

tortoise/queryset.py

@@ -9,7 +9,6 @@
 from tortoise.backends.base.client import BaseDBAsyncClient
 from tortoise.exceptions import DoesNotExist, FieldError, IntegrityError, MultipleObjectsReturned
 from tortoise.query_utils import Prefetch, Q, QueryModifier, _get_joins_for_related_field
-from tortoise.utils import QueryAsyncIterator
 
 # Empty placeholder - Should never be edited.
 QUERY = Query()
@@ -81,8 +80,9 @@ def __await__(self):
         self._make_query()
         return self._execute().__await__()
 
-    def __aiter__(self) -> QueryAsyncIterator:
-        return QueryAsyncIterator(self)
+    async def __aiter__(self):
+        for val in await self:
+            yield val
 
     async def _execute(self):
         raise NotImplementedError()  # pragma: nocoverage

tortoise/utils.py

@@ -1,33 +1,9 @@
 import logging
-from typing import Awaitable, Callable, Iterator, List, Optional
+from typing import List
 
 logger = logging.getLogger("tortoise")
 
 
-class QueryAsyncIterator:
-    __slots__ = ("query", "sequence", "_sequence_iterator", "_callback")
-
-    def __init__(self, query: Awaitable[Iterator], callback: Optional[Callable] = None) -> None:
-        self.query = query
-        self.sequence: Optional[Iterator] = None
-        self._sequence_iterator = None
-        self._callback = callback
-
-    def __aiter__(self):
-        return self  # pragma: nocoverage
-
-    async def __anext__(self):
-        if self.sequence is None:
-            self.sequence = await self.query
-            self._sequence_iterator = self.sequence.__iter__()
-            if self._callback:  # pragma: no branch
-                await self._callback(self)
-        try:
-            return next(self._sequence_iterator)
-        except StopIteration:
-            raise StopAsyncIteration
-
-
 def get_schema_sql(client, safe: bool) -> str:
     generator = client.schema_generator(client)
     return generator.get_create_schema_sql(safe)