From 1e1f3bab464d497a9250590a72b025f6095b20a7 Mon Sep 17 00:00:00 2001
From: Tom Christie <tom@tomchristie.com>
Date: Mon, 10 Dec 2018 14:37:30 +0000
Subject: [PATCH] Add executemany (#259)

---
 starlette/__init__.py          |  2 +-
 starlette/database/core.py     |  5 ++++-
 starlette/database/postgres.py | 17 +++++++++++++++--
 tests/test_database.py         | 25 +++++++++++++++++++++++++
 4 files changed, 45 insertions(+), 4 deletions(-)

diff --git a/starlette/__init__.py b/starlette/__init__.py
index f5b77301..a25765c3 100644
--- a/starlette/__init__.py
+++ b/starlette/__init__.py
@@ -1 +1 @@
-__version__ = "0.9.7"
+__version__ = "0.9.8"
diff --git a/starlette/database/core.py b/starlette/database/core.py
index f2d01418..bf53bc69 100644
--- a/starlette/database/core.py
+++ b/starlette/database/core.py
@@ -61,7 +61,10 @@ class DatabaseSession:
         row = await self.fetchone(query)
         return row[index]
 
-    async def execute(self, query: ClauseElement) -> typing.Any:
+    async def execute(self, query: ClauseElement) -> None:
+        raise NotImplementedError()  # pragma: no cover
+
+    async def executemany(self, query: ClauseElement, values: list) -> None:
         raise NotImplementedError()  # pragma: no cover
 
     def transaction(self) -> "DatabaseTransaction":
diff --git a/starlette/database/postgres.py b/starlette/database/postgres.py
index 63b141e8..e2e0530b 100644
--- a/starlette/database/postgres.py
+++ b/starlette/database/postgres.py
@@ -71,12 +71,25 @@ class PostgresSession(DatabaseSession):
         finally:
             await self.release_connection()
 
-    async def execute(self, query: ClauseElement) -> typing.Any:
+    async def execute(self, query: ClauseElement) -> None:
         query, args = compile(query, dialect=self.dialect)
 
         conn = await self.acquire_connection()
         try:
-            return await conn.execute(query, *args)
+            await conn.execute(query, *args)
+        finally:
+            await self.release_connection()
+
+    async def executemany(self, query: ClauseElement, values: list) -> None:
+        conn = await self.acquire_connection()
+        try:
+            # asyncpg uses prepared statements under the hood, so we just
+            # loop through multiple executes here, which should all end up
+            # using the same prepared statement.
+            for item in values:
+                single_query = query.values(item)
+                single_query, args = compile(single_query, dialect=self.dialect)
+                await conn.execute(single_query, *args)
         finally:
             await self.release_connection()
 
diff --git a/tests/test_database.py b/tests/test_database.py
index 6bdd9cab..803772a0 100644
--- a/tests/test_database.py
+++ b/tests/test_database.py
@@ -56,6 +56,14 @@ async def add_note(request):
     return JSONResponse({"text": data["text"], "completed": data["completed"]})
 
 
+@app.route("/notes/bulk_create", methods=["POST"])
+async def bulk_create_notes(request):
+    data = await request.json()
+    query = notes.insert()
+    await request.database.executemany(query, data)
+    return JSONResponse({"notes": data})
+
+
 @app.route("/notes/{note_id:int}", methods=["GET"])
 async def read_note(request):
     note_id = request.path_params["note_id"]
@@ -108,6 +116,23 @@ def test_database():
         assert response.json() == "buy the milk"
 
 
+def test_database_executemany():
+    with TestClient(app) as client:
+        data = [
+            {"text": "buy the milk", "completed": True},
+            {"text": "walk the dog", "completed": False},
+        ]
+        response = client.post("/notes/bulk_create", json=data)
+        assert response.status_code == 200
+
+        response = client.get("/notes")
+        assert response.status_code == 200
+        assert response.json() == [
+            {"text": "buy the milk", "completed": True},
+            {"text": "walk the dog", "completed": False},
+        ]
+
+
 def test_database_isolated_during_test_cases():
     """
     Using `TestClient` as a context manager