factory method gino.ext.starlette (#538)

* factory method starlette.

* Test for factory method gino.ext.starlette.

* remove unused import

* Chgs to PR rec by @wwwjfy, rm chgs Pipfile.lock, .gitignore.

* Revert "Chgs to PR rec by @wwwjfy, rm chgs Pipfile.lock, .gitignore."

This reverts commit c75f26a.

* changes from suggestions on PR

Author: jim-obrien-orig

gino/ext/starlette.py

@@ -1,12 +1,11 @@
 # noinspection PyPackageRequirements
-from starlette.applications import Starlette
+from sqlalchemy.engine.url import URL
 # noinspection PyPackageRequirements
-from starlette.types import Message, Receive, Scope, Send
+from starlette import status
 # noinspection PyPackageRequirements
 from starlette.exceptions import HTTPException
 # noinspection PyPackageRequirements
-from starlette import status
-from sqlalchemy.engine.url import URL
+from starlette.types import Message, Receive, Scope, Send
 
 from ..api import Gino as _Gino, GinoExecutor as _Executor
 from ..engine import GinoConnection as _Connection, GinoEngine as _Engine
@@ -94,6 +93,7 @@ async def receiver() -> Message:
                 elif message["type"] == "lifespan.shutdown":
                     await self.db.pop_bind().close()
                 return message
+
             await self.app(scope, receiver, send)
             return
 
@@ -146,7 +146,7 @@ class Gino(_Gino):
     model_base_classes = _Gino.model_base_classes + (StarletteModelMixin,)
     query_executor = GinoExecutor
 
-    def __init__(self, app: Starlette, *args, **kwargs):
+    def __init__(self, app=None, *args, **kwargs):
         self.config = dict()
         if 'dsn' in kwargs:
             self.config['dsn'] = kwargs.pop('dsn')
@@ -168,7 +168,10 @@ def __init__(self, app: Starlette, *args, **kwargs):
         self.config['kwargs'] = kwargs.pop('kwargs', dict())
 
         super().__init__(*args, **kwargs)
+        if app is not None:
+            self.init_app(app)
 
+    def init_app(self, app):
         app.add_middleware(_Middleware, db=self)
 
     async def first_or_404(self, *args, **kwargs):

tests/test_starlette.py

@@ -28,7 +28,13 @@ async def _app(**kwargs):
             max_inactive_connection_lifetime=_MAX_INACTIVE_CONNECTION_LIFETIME,
         ),
     })
-    db = Gino(app, **kwargs)
+    factory = kwargs.pop('factory', False)
+
+    if factory:
+        db = Gino(**kwargs)
+        db.init_app(app)
+    else:
+        db = Gino(app, **kwargs)
 
     class User(db.Model):
         __tablename__ = 'gino_users'
@@ -95,6 +101,18 @@ async def app():
     )
 
 
+@pytest.fixture
+@async_generator
+async def app_factory():
+    await _app(
+        factory=True,
+        host=DB_ARGS['host'],
+        port=DB_ARGS['port'],
+        user=DB_ARGS['user'],
+        password=DB_ARGS['password'],
+        database=DB_ARGS['database'],
+    )
+
 @pytest.fixture
 @async_generator
 async def app_ssl(ssl_ctx):
@@ -157,3 +175,6 @@ def test_ssl(app_ssl):
 
 def test_dsn(app_dsn):
     _test(app_dsn)
+
+def test_app_factory(app_factory):
+    _test(app_factory)