Allow SQLite query parameters and support cached databases (#561)

* add support for sqlite connection string query parameters, cached memory databases

* add additional comments #196

* tweaked comments #196

* Lint

---------

Co-authored-by: Nathan Joshi <nvjoshi@Nathans-MacBook-Pro.local>

databases/backends/sqlite.py

@@ -1,6 +1,8 @@
 import logging
+import sqlite3
 import typing
 import uuid
+from urllib.parse import urlencode
 
 import aiosqlite
 from sqlalchemy.dialects.sqlite import pysqlite
@@ -45,7 +47,9 @@ async def connect(self) -> None:
         # )
 
     async def disconnect(self) -> None:
-        pass
+        # if it extsis, remove reference to connection to cached in-memory database on disconnect
+        if self._pool._memref:
+            self._pool._memref = None
         # assert self._pool is not None, "DatabaseBackend is not running"
         # self._pool.close()
         # await self._pool.wait_closed()
@@ -57,12 +61,20 @@ def connection(self) -> "SQLiteConnection":
 
 class SQLitePool:
     def __init__(self, url: DatabaseURL, **options: typing.Any) -> None:
-        self._url = url
+        self._database = url.database
+        self._memref = None
+        # add query params to database connection string
+        if url.options:
+            self._database += "?" + urlencode(url.options)
         self._options = options
 
+        if url.options and "cache" in url.options:
+            # reference to a connection to the cached in-memory database must be held to keep it from being deleted
+            self._memref = sqlite3.connect(self._database, **self._options)
+
     async def acquire(self) -> aiosqlite.Connection:
         connection = aiosqlite.connect(
-            database=self._url.database, isolation_level=None, **self._options
+            database=self._database, isolation_level=None, **self._options
         )
         await connection.__aenter__()
         return connection

requirements.txt

@@ -8,8 +8,8 @@ aiosqlite==0.17.0
 asyncpg==0.26.0
 
 # Sync database drivers for standard tooling around setup/teardown/migrations.
-psycopg2-binary==2.9.3
-pymysql==1.0.2
+# psycopg2-binary==2.9.3
+# pymysql==1.0.2
 
 # Testing
 autoflake==1.4

tests/test_databases.py

@@ -6,6 +6,7 @@
 import itertools
 import os
 import re
+import sqlite3
 from typing import MutableMapping
 from unittest.mock import MagicMock, patch
 
@@ -1529,6 +1530,67 @@ async def test_result_named_access(database_url):
         assert result.completed is True
 
 
+@pytest.mark.parametrize("database_url", DATABASE_URLS)
+@async_adapter
+async def test_mapping_property_interface(database_url):
+    """
+    Test that all connections implement interface with `_mapping` property
+    """
+    async with Database(database_url) as database:
+        query = notes.select()
+        single_result = await database.fetch_one(query=query)
+        assert single_result._mapping["text"] == "example1"
+        assert single_result._mapping["completed"] is True
+
+        list_result = await database.fetch_all(query=query)
+        assert list_result[0]._mapping["text"] == "example1"
+        assert list_result[0]._mapping["completed"] is True
+
+
+@async_adapter
+async def test_should_not_maintain_ref_when_no_cache_param():
+    async with Database("sqlite:///file::memory:", uri=True) as database:
+        query = sqlalchemy.schema.CreateTable(notes)
+        await database.execute(query)
+
+        query = notes.insert()
+        values = {"text": "example1", "completed": True}
+        with pytest.raises(sqlite3.OperationalError):
+            await database.execute(query, values)
+
+
+@async_adapter
+async def test_should_maintain_ref_when_cache_param():
+    async with Database("sqlite:///file::memory:?cache=shared", uri=True) as database:
+        query = sqlalchemy.schema.CreateTable(notes)
+        await database.execute(query)
+
+        query = notes.insert()
+        values = {"text": "example1", "completed": True}
+        await database.execute(query, values)
+
+        query = notes.select().where(notes.c.text == "example1")
+        result = await database.fetch_one(query=query)
+        assert result.text == "example1"
+        assert result.completed is True
+
+
+@async_adapter
+async def test_should_remove_ref_on_disconnect():
+    async with Database("sqlite:///file::memory:?cache=shared", uri=True) as database:
+        query = sqlalchemy.schema.CreateTable(notes)
+        await database.execute(query)
+
+        query = notes.insert()
+        values = {"text": "example1", "completed": True}
+        await database.execute(query, values)
+
+    async with Database("sqlite:///file::memory:?cache=shared", uri=True) as database:
+        query = notes.select()
+        with pytest.raises(sqlite3.OperationalError):
+            await database.fetch_all(query=query)
+
+
 @pytest.mark.parametrize("database_url", DATABASE_URLS)
 @async_adapter
 async def test_mapping_property_interface(database_url):