- implement postgres connection pool

- adapt current sqlalchemy based methods to produce raw sql

Author: grillazz

app/api/stuff.py

@@ -1,4 +1,5 @@
-from fastapi import APIRouter, Depends, HTTPException, status
+from fastapi import APIRouter, Depends, HTTPException, status, Request
+from fastapi.exceptions import ResponseValidationError
 from sqlalchemy.exc import SQLAlchemyError
 from sqlalchemy.ext.asyncio import AsyncSession
 
@@ -21,7 +22,6 @@ async def create_multi_stuff(
         db_session.add_all(stuff_instances)
         await db_session.commit()
     except SQLAlchemyError as ex:
-        # logger.exception(ex)
         raise HTTPException(
             status_code=status.HTTP_422_UNPROCESSABLE_ENTITY, detail=repr(ex)
         ) from ex
@@ -43,10 +43,29 @@ async def create_stuff(
 
 @router.get("/{name}", response_model=StuffResponse)
 async def find_stuff(
+    request: Request,
     name: str,
+    pool: bool = False,
     db_session: AsyncSession = Depends(get_db),
 ):
-    return await Stuff.find(db_session, name)
+    try:
+        if not pool:
+            result = await Stuff.find(db_session, name)
+        else:
+            # execute the compiled SQL statement
+            stmt = await Stuff.find(db_session, name, compile_sql=True)
+            result = await request.app.postgres_pool.fetchrow(str(stmt))
+            result = dict(result)
+    except SQLAlchemyError as ex:
+        raise HTTPException(
+            status_code=status.HTTP_422_UNPROCESSABLE_ENTITY, detail=repr(ex)
+        ) from ex
+    if not result:
+        raise HTTPException(
+            status_code=status.HTTP_404_NOT_FOUND,
+            detail=f"Stuff with name {name} not found.",
+        )
+    return result
 
 
 @router.delete("/{name}")

app/config.py

@@ -70,5 +70,29 @@ def asyncpg_url(self) -> PostgresDsn:
             path=self.POSTGRES_DB,
         )
 
+    @computed_field
+    @property
+    def postgres_url(self) -> PostgresDsn:
+        """
+        This is a computed field that generates a PostgresDsn URL
+
+        The URL is built using the MultiHostUrl.build method, which takes the following parameters:
+        - scheme: The scheme of the URL. In this case, it is "postgres".
+        - username: The username for the Postgres database, retrieved from the POSTGRES_USER environment variable.
+        - password: The password for the Postgres database, retrieved from the POSTGRES_PASSWORD environment variable.
+        - host: The host of the Postgres database, retrieved from the POSTGRES_HOST environment variable.
+        - path: The path of the Postgres database, retrieved from the POSTGRES_DB environment variable.
+
+        Returns:
+            PostgresDsn: The constructed PostgresDsn URL.
+        """
+        return MultiHostUrl.build(
+            scheme="postgres",
+            username=self.POSTGRES_USER,
+            password=self.POSTGRES_PASSWORD,
+            host=self.POSTGRES_HOST,
+            path=self.POSTGRES_DB,
+        )
+
 
 settings = Settings()

app/main.py

@@ -1,3 +1,4 @@
+import asyncpg
 from contextlib import asynccontextmanager
 
 from fastapi import FastAPI, Depends
@@ -7,6 +8,7 @@
 from app.api.nonsense import router as nonsense_router
 from app.api.shakespeare import router as shakespeare_router
 from app.api.stuff import router as stuff_router
+from app.config import settings as global_settings
 from app.utils.logging import AppLogger
 from app.api.user import router as user_router
 from app.api.health import router as health_router
@@ -21,15 +23,26 @@ async def lifespan(_app: FastAPI):
     # Load the redis connection
     _app.redis = await get_redis()
 
+    _postgres_dsn = global_settings.postgres_url.unicode_string()
+
     try:
         # Initialize the cache with the redis connection
         redis_cache = await get_cache()
         FastAPICache.init(RedisBackend(redis_cache), prefix="fastapi-cache")
         logger.info(FastAPICache.get_cache_status_header())
+        # Initialize the postgres connection pool
+        _app.postgres_pool = await asyncpg.create_pool(
+            dsn=_postgres_dsn,
+            min_size=5,
+            max_size=20,
+        )
+        logger.info(f"Postgres pool created: {_app.postgres_pool.get_idle_size()=}")
         yield
     finally:
         # close redis connection and release the resources
         await _app.redis.close()
+        # close postgres connection pool and release the resources
+        await _app.postgres_pool.close()
 
 
 app = FastAPI(title="Stuff And Nonsense API", version="0.6", lifespan=lifespan)

app/models/stuff.py

@@ -24,23 +24,12 @@ class Stuff(Base):
     )
 
     @classmethod
-    async def find(cls, db_session: AsyncSession, name: str):
-        """
-
-        :param db_session:
-        :param name:
-        :return:
-        """
+    async def find(cls, db_session: AsyncSession, name: str, compile_sql: bool = False):
         stmt = select(cls).options(joinedload(cls.nonsense)).where(cls.name == name)
+        if compile_sql:
+            return stmt.compile(compile_kwargs={"literal_binds": True})
         result = await db_session.execute(stmt)
-        instance = result.scalars().first()
-        if instance is None:
-            raise HTTPException(
-                status_code=status.HTTP_404_NOT_FOUND,
-                detail={"Not found": f"There is no record for name: {name}"},
-            )
-        else:
-            return instance
+        return result.scalars().first()
 
 
 class StuffFullOfNonsense(Base):

tests/api/test_stuff.py

@@ -1,4 +1,3 @@
-
 import pytest
 from fastapi import status
 from httpx import AsyncClient