Refactor the LocalSchemaTransport into an AsyncTransport (#84)

Author: leszekhanusz

gql/client.py

@@ -1,5 +1,4 @@
 import asyncio
-from inspect import isawaitable
 from typing import Any, AsyncGenerator, Dict, Generator, Optional, Union, cast
 
 from graphql import (
@@ -116,9 +115,6 @@ def execute(self, document: DocumentNode, *args, **kwargs) -> Dict:
 
             result = self.transport.execute(document, *args, **kwargs)
 
-            assert not isawaitable(result), "Transport returned an awaitable result."
-            result = cast(ExecutionResult, result)
-
             if result.errors:
                 raise TransportQueryError(str(result.errors[0]))
 

gql/transport/local_schema.py

@@ -1,11 +1,12 @@
-from typing import Awaitable, Union
+from inspect import isawaitable
+from typing import Any, AsyncGenerator, AsyncIterator, Awaitable, Coroutine, cast
 
-from graphql import DocumentNode, ExecutionResult, GraphQLSchema, execute
+from graphql import DocumentNode, ExecutionResult, GraphQLSchema, execute, subscribe
 
-from gql.transport import Transport
+from gql.transport import AsyncTransport
 
 
-class LocalSchemaTransport(Transport):
+class LocalSchemaTransport(AsyncTransport):
     """A transport for executing GraphQL queries against a local schema."""
 
     def __init__(
@@ -17,14 +18,59 @@ def __init__(
         """
         self.schema = schema
 
-    def execute(
-        self, document: DocumentNode, *args, **kwargs
-    ) -> Union[ExecutionResult, Awaitable[ExecutionResult]]:
-        """Execute the given document against the configured local schema.
+    async def connect(self):
+        """No connection needed on local transport
+        """
+        pass
+
+    async def close(self):
+        """No close needed on local transport
+        """
+        pass
 
-        :param document: GraphQL query as AST Node object.
-        :param args: Positional options for execute method from graphql-core.
-        :param kwargs: Keyword options passed to execute method from graphql-core.
-        :return: ExecutionResult (either as value or awaitable)
+    async def execute(
+        self, document: DocumentNode, *args, **kwargs,
+    ) -> ExecutionResult:
+        """Execute the provided document AST for on a local GraphQL Schema.
         """
-        return execute(self.schema, document, *args, **kwargs)
+
+        result_or_awaitable = execute(self.schema, document, *args, **kwargs)
+
+        execution_result: ExecutionResult
+
+        if isawaitable(result_or_awaitable):
+            result_or_awaitable = cast(Awaitable[ExecutionResult], result_or_awaitable)
+            execution_result = await result_or_awaitable
+        else:
+            result_or_awaitable = cast(ExecutionResult, result_or_awaitable)
+            execution_result = result_or_awaitable
+
+        return execution_result
+
+    async def subscribe(
+        self, document: DocumentNode, *args, **kwargs,
+    ) -> AsyncGenerator[ExecutionResult, None]:
+        """Send a query and receive the results using an async generator
+
+        The query can be a graphql query, mutation or subscription
+
+        The results are sent as an ExecutionResult object
+        """
+
+        subscribe_result = subscribe(self.schema, document, *args, **kwargs)
+
+        if isinstance(subscribe_result, ExecutionResult):
+            yield ExecutionResult
+
+        else:
+            # if we don't get an ExecutionResult, then we should receive
+            # a Coroutine returning an AsyncIterator[ExecutionResult]
+
+            subscribe_coro = cast(
+                Coroutine[Any, Any, AsyncIterator[ExecutionResult]], subscribe_result
+            )
+
+            subscribe_generator = await subscribe_coro
+
+            async for result in subscribe_generator:
+                yield result

gql/transport/transport.py

@@ -1,20 +1,17 @@
 import abc
-from typing import Awaitable, Union
 
 from graphql import DocumentNode, ExecutionResult
 
 
 class Transport:
     @abc.abstractmethod
-    def execute(
-        self, document: DocumentNode, *args, **kwargs
-    ) -> Union[ExecutionResult, Awaitable[ExecutionResult]]:
+    def execute(self, document: DocumentNode, *args, **kwargs) -> ExecutionResult:
         """Execute GraphQL query.
 
         Execute the provided document AST for either a remote or local GraphQL Schema.
 
         :param document: GraphQL query as AST Node or Document object.
-        :return: ExecutionResult (either as value or awaitable)
+        :return: ExecutionResult
         """
         raise NotImplementedError(
             "Any Transport subclass must implement execute method"
@@ -27,4 +24,4 @@ def close(self):
         from it. This is currently used by the RequestsHTTPTransport transport to close
         the session's connection pool.
         """
-        pass
+        pass  # pragma: no cover

tests/starwars/test_subscription.py

@@ -1,11 +1,21 @@
 import pytest
 from graphql import subscribe
 
-from gql import gql
+from gql import Client, gql
 
 from .fixtures import reviews
 from .schema import StarWarsSchema
 
+subscription_str = """
+    subscription ListenEpisodeReviews($ep: Episode!) {
+      reviewAdded(episode: $ep) {
+        stars,
+        commentary,
+        episode
+      }
+    }
+"""
+
 
 @pytest.mark.asyncio
 async def test_subscription_support():
@@ -15,17 +25,8 @@ async def test_subscription_support():
         {"stars": 5, "commentary": "This is a great movie!", "episode": 6},
     ]
 
-    subs = gql(
-        """
-        subscription ListenEpisodeReviews($ep: Episode!) {
-          reviewAdded(episode: $ep) {
-            stars,
-            commentary,
-            episode
-          }
-        }
-    """
-    )
+    subs = gql(subscription_str)
+
     params = {"ep": "JEDI"}
     expected = [{**review, "episode": "JEDI"} for review in reviews[6]]
 
@@ -34,3 +35,25 @@ async def test_subscription_support():
     result = [result.data["reviewAdded"] async for result in ai]
 
     assert result == expected
+
+
+@pytest.mark.asyncio
+async def test_subscription_support_using_client():
+    # reset review data for this test
+    reviews[6] = [
+        {"stars": 3, "commentary": "Was expecting more stuff", "episode": 6},
+        {"stars": 5, "commentary": "This is a great movie!", "episode": 6},
+    ]
+
+    subs = gql(subscription_str)
+
+    params = {"ep": "JEDI"}
+    expected = [{**review, "episode": "JEDI"} for review in reviews[6]]
+
+    results = []
+
+    async with Client(schema=StarWarsSchema) as session:
+        async for result in session.subscribe(subs, variable_values=params):
+            results.append(result["reviewAdded"])
+
+    assert results == expected

tests/test_client.py

@@ -171,6 +171,6 @@ def test_gql():
     """
     )
 
-    with Client(schema=schema) as client:
-        result = client.execute(query)
+    client = Client(schema=schema)
+    result = client.execute(query)
     assert result["user"] is None