setup basic fastapi backend

.env.example

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+SQLALCHEMY_DATABASE_URI=postgresql+asyncpg://username:password@host:port/database_name

Dockerfile

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+# Use official Python 3.12 slim image
+FROM python:3.12-slim
+
+# Set environment variables
+ENV SQLALCHEMY_DATABASE_URI=sqlite+aiosqlite:///:memory:
+ENV PYTHONUNBUFFERED=1
+ENV POETRY_VERSION=1.8.2
+
+# Set work directory
+WORKDIR /app
+
+# Install system dependencies
+RUN apt-get update && apt-get install -y \
+    curl \
+    build-essential \
+    && rm -rf /var/lib/apt/lists/*
+
+# Install Poetry
+RUN curl -sSL https://install.python-poetry.org | python3 -
+ENV PATH="/root/.local/bin:$PATH"
+
+# Copy only dependency files first to leverage Docker cache
+COPY pyproject.toml poetry.lock* /app/
+
+# Install dependencies (without creating a virtualenv)
+RUN poetry config virtualenvs.create false \
+ && poetry install --no-interaction --no-ansi
+
+# Copy the entire project
+COPY . /app/
+
+# Expose the port Uvicorn will run on
+EXPOSE 8000
+
+# Run the FastAPI application
+CMD ["uvicorn", "src.app:app", "--reload", "--host", "0.0.0.0", "--port", "8000"]

alembic.ini

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+# A generic, single database configuration.
+
+[alembic]
+# path to migration scripts.
+# this is typically a path given in POSIX (e.g. forward slashes)
+# format, relative to the token %(here)s which refers to the location of this
+# ini file
+script_location = %(here)s/alembic
+
+# template used to generate migration file names; The default value is %%(rev)s_%%(slug)s
+# Uncomment the line below if you want the files to be prepended with date and time
+# see https://alembic.sqlalchemy.org/en/latest/tutorial.html#editing-the-ini-file
+# for all available tokens
+# file_template = %%(year)d_%%(month).2d_%%(day).2d_%%(hour).2d%%(minute).2d-%%(rev)s_%%(slug)s
+
+# sys.path path, will be prepended to sys.path if present.
+# defaults to the current working directory.  for multiple paths, the path separator
+# is defined by "path_separator" below.
+prepend_sys_path = .
+
+# timezone to use when rendering the date within the migration file
+# as well as the filename.
+# If specified, requires the python>=3.9 or backports.zoneinfo library and tzdata library.
+# Any required deps can installed by adding `alembic[tz]` to the pip requirements
+# string value is passed to ZoneInfo()
+# leave blank for localtime
+# timezone =
+
+# max length of characters to apply to the "slug" field
+# truncate_slug_length = 40
+
+# set to 'true' to run the environment during
+# the 'revision' command, regardless of autogenerate
+# revision_environment = false
+
+# set to 'true' to allow .pyc and .pyo files without
+# a source .py file to be detected as revisions in the
+# versions/ directory
+# sourceless = false
+
+# version location specification; This defaults
+# to <script_location>/versions.  When using multiple version
+# directories, initial revisions must be specified with --version-path.
+# The path separator used here should be the separator specified by "path_separator"
+# below.
+# version_locations = %(here)s/bar:%(here)s/bat:%(here)s/alembic/versions
+
+# path_separator; This indicates what character is used to split lists of file
+# paths, including version_locations and prepend_sys_path within configparser
+# files such as alembic.ini.
+# The default rendered in new alembic.ini files is "os", which uses os.pathsep
+# to provide os-dependent path splitting.
+#
+# Note that in order to support legacy alembic.ini files, this default does NOT
+# take place if path_separator is not present in alembic.ini.  If this
+# option is omitted entirely, fallback logic is as follows:
+#
+# 1. Parsing of the version_locations option falls back to using the legacy
+#    "version_path_separator" key, which if absent then falls back to the legacy
+#    behavior of splitting on spaces and/or commas.
+# 2. Parsing of the prepend_sys_path option falls back to the legacy
+#    behavior of splitting on spaces, commas, or colons.
+#
+# Valid values for path_separator are:
+#
+# path_separator = :
+# path_separator = ;
+# path_separator = space
+# path_separator = newline
+#
+# Use os.pathsep. Default configuration used for new projects.
+path_separator = os
+
+
+# set to 'true' to search source files recursively
+# in each "version_locations" directory
+# new in Alembic version 1.10
+# recursive_version_locations = false
+
+# the output encoding used when revision files
+# are written from script.py.mako
+# output_encoding = utf-8
+
+# database URL.  This is consumed by the user-maintained env.py script only.
+# other means of configuring database URLs may be customized within the env.py
+# file.
+sqlalchemy.url = driver://user:pass@localhost/dbname
+
+
+[post_write_hooks]
+# post_write_hooks defines scripts or Python functions that are run
+# on newly generated revision scripts.  See the documentation for further
+# detail and examples
+
+# format using "black" - use the console_scripts runner, against the "black" entrypoint
+# hooks = black
+# black.type = console_scripts
+# black.entrypoint = black
+# black.options = -l 79 REVISION_SCRIPT_FILENAME
+
+# lint with attempts to fix using "ruff" - use the exec runner, execute a binary
+# hooks = ruff
+# ruff.type = exec
+# ruff.executable = %(here)s/.venv/bin/ruff
+# ruff.options = check --fix REVISION_SCRIPT_FILENAME
+
+# Logging configuration.  This is also consumed by the user-maintained
+# env.py script only.
+[loggers]
+keys = root,sqlalchemy,alembic
+
+[handlers]
+keys = console
+
+[formatters]
+keys = generic
+
+[logger_root]
+level = WARNING
+handlers = console
+qualname =
+
+[logger_sqlalchemy]
+level = WARNING
+handlers =
+qualname = sqlalchemy.engine
+
+[logger_alembic]
+level = INFO
+handlers =
+qualname = alembic
+
+[handler_console]
+class = StreamHandler
+args = (sys.stderr,)
+level = NOTSET
+formatter = generic
+
+[formatter_generic]
+format = %(levelname)-5.5s [%(name)s] %(message)s
+datefmt = %H:%M:%S

alembic/README

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+Generic single-database configuration with an async dbapi.

alembic/env.py

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+import asyncio
+from logging.config import fileConfig
+
+from sqlalchemy import pool
+from sqlalchemy.engine import Connection
+from sqlalchemy.ext.asyncio import async_engine_from_config
+
+from alembic import context
+
+from src.models import *
+
+# this is the Alembic Config object, which provides
+# access to the values within the .ini file in use.
+config = context.config
+
+# Interpret the config file for Python logging.
+# This line sets up loggers basically.
+if config.config_file_name is not None:
+    fileConfig(config.config_file_name)
+
+# add your model's MetaData object here
+# for 'autogenerate' support
+# from myapp import mymodel
+# target_metadata = mymodel.Base.metadata
+target_metadata = Base.metadata
+
+# other values from the config, defined by the needs of env.py,
+# can be acquired:
+# my_important_option = config.get_main_option("my_important_option")
+# ... etc.
+
+
+def run_migrations_offline() -> None:
+    """Run migrations in 'offline' mode.
+
+    This configures the context with just a URL
+    and not an Engine, though an Engine is acceptable
+    here as well.  By skipping the Engine creation
+    we don't even need a DBAPI to be available.
+
+    Calls to context.execute() here emit the given string to the
+    script output.
+
+    """
+    url = config.get_main_option("sqlalchemy.url")
+    context.configure(
+        url=url,
+        target_metadata=target_metadata,
+        literal_binds=True,
+        dialect_opts={"paramstyle": "named"},
+    )
+
+    with context.begin_transaction():
+        context.run_migrations()
+
+
+def do_run_migrations(connection: Connection) -> None:
+    context.configure(connection=connection, target_metadata=target_metadata)
+
+    with context.begin_transaction():
+        context.run_migrations()
+
+
+async def run_async_migrations() -> None:
+    """In this scenario we need to create an Engine
+    and associate a connection with the context.
+
+    """
+
+    connectable = async_engine_from_config(
+        config.get_section(config.config_ini_section, {}),
+        prefix="sqlalchemy.",
+        poolclass=pool.NullPool,
+    )
+
+    async with connectable.connect() as connection:
+        await connection.run_sync(do_run_migrations)
+
+    await connectable.dispose()
+
+
+def run_migrations_online() -> None:
+    """Run migrations in 'online' mode."""
+
+    connectable = config.attributes.get("connection", None)
+
+    if connectable is None:
+        asyncio.run(run_async_migrations())
+    else:
+        do_run_migrations(connectable)
+
+
+if context.is_offline_mode():
+    run_migrations_offline()
+else:
+    run_migrations_online()

alembic/script.py.mako

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+"""${message}
+
+Revision ID: ${up_revision}
+Revises: ${down_revision | comma,n}
+Create Date: ${create_date}
+
+"""
+from typing import Sequence, Union
+
+from alembic import op
+import sqlalchemy as sa
+${imports if imports else ""}
+
+# revision identifiers, used by Alembic.
+revision: str = ${repr(up_revision)}
+down_revision: Union[str, None] = ${repr(down_revision)}
+branch_labels: Union[str, Sequence[str], None] = ${repr(branch_labels)}
+depends_on: Union[str, Sequence[str], None] = ${repr(depends_on)}
+
+
+def upgrade() -> None:
+    """Upgrade schema."""
+    ${upgrades if upgrades else "pass"}
+
+
+def downgrade() -> None:
+    """Downgrade schema."""
+    ${downgrades if downgrades else "pass"}

pyproject.toml

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+[tool.poetry]
+name = "ipns-sow"
+version = "0.1.0"
+description = ""
+authors = ["Aryan Jain <77013565+aryanjain1908@users.noreply.github.com>"]
+readme = "README.md"
+
+[tool.poetry.dependencies]
+python = "^3.12"
+uvicorn = {extras = ["standard"], version = "^0.34.3"}
+fastapi = "^0.115.12"
+python-dotenv = "^1.1.0"
+alembic = "^1.16.1"
+asyncpg = "^0.30.0"
+loguru = "^0.7.3"
+pydantic = "^2.11.5"
+aiosqlite = "^0.21.0"
+
+
+[build-system]
+requires = ["poetry-core"]
+build-backend = "poetry.core.masonry.api"

src/__init__.py

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+from dotenv import load_dotenv
+import os
+
+from .app import app
+from .config import logger
+
+load_dotenv()
+
+if not os.getenv("SQLALCHEMY_DATABASE_URI"):
+    logger.error("SQLALCHEMY_DATABASE_URI is not set")
+    raise ValueError("SQLALCHEMY_DATABASE_URI is not set")
+
+__all__ = ["app"]
+__version__ = "0.1.0"
+__author__ = "Aryan Jain"

src/app.py

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+import asyncio
+import os
+from contextlib import asynccontextmanager
+from threading import Thread
+
+from alembic import command
+from alembic.config import Config
+from fastapi import FastAPI
+from fastapi.middleware.cors import CORSMiddleware
+from fastapi.responses import RedirectResponse
+
+from src.config import DatabaseConfig, logger
+from src.controllers import api_router
+
+
+
+def run_upgrade(connection, alembic_config: Config):
+    alembic_config.attributes["connection"] = connection
+    command.upgrade(alembic_config, "head")
+
+
+async def run_migrations():
+    logger.info("Running migrations if any...")
+    alembic_config = Config("alembic.ini")
+    alembic_config.set_main_option(
+        "sqlalchemy.url", os.getenv("SQLALCHEMY_DATABASE_URI")
+    )
+    async with DatabaseConfig.get_engine().begin() as session:
+        await session.run_sync(run_upgrade, alembic_config)
+
+
+@asynccontextmanager
+async def lifespan(app: FastAPI):
+    try:
+        logger.info("Starting up the application...")
+        await run_migrations()
+        logger.info("Application started successfully...")
+        yield
+    except Exception as e:
+        logger.error(f"Error during startup: {str(e)}")
+        raise
+    finally:
+        logger.info("Shutting down the application...")
+        logger.info("Application shutdown complete.")
+
+
+app = FastAPI(lifespan=lifespan)
+
+
+app.add_middleware(
+    CORSMiddleware,
+    # allow_origins=os.getenv(
+    #     "CORS_ALLOW_ORIGINS", "http://localhost, http://127.0.0.1"
+    # ).split(", "),
+    allow_origins=["*"],
+    allow_credentials=False,
+    allow_methods=["*"],
+    allow_headers=["*"],
+)
+
+
+@app.get("/")
+async def check_health():
+    return RedirectResponse(url="/docs")
+
+
+app.include_router(api_router, prefix="/api/v1")

src/config/__init__.py

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+from ._database_config import DatabaseConfig
+from ._logger import logger
+
+__all__ = [
+    "DatabaseConfig",
+    "logger",
+]
+__version__ = "0.1.0"
+__author__ = "Aryan Jain"

src/config/_database_config.py

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+import os
+import threading
+from contextlib import asynccontextmanager
+
+from sqlalchemy.ext.asyncio import async_sessionmaker, create_async_engine
+
+
+class DatabaseConfig:
+    _thread_local = threading.local()
+
+    @classmethod
+    def get_engine(cls):
+        if not hasattr(cls._thread_local, "engine"):
+            cls._thread_local.engine = create_async_engine(
+                url=os.getenv("SQLALCHEMY_DATABASE_URI"),
+                pool_pre_ping=True,
+                pool_recycle=3600,
+            )
+        return cls._thread_local.engine
+
+    @classmethod
+    def _get_session_factory(cls):
+        if not hasattr(cls._thread_local, "session_factory"):
+            cls._thread_local.session_factory = async_sessionmaker(
+                bind=cls.get_engine(),
+                autoflush=False,
+                autocommit=False,
+                expire_on_commit=False,
+            )
+        return cls._thread_local.session_factory
+
+    @classmethod
+    @asynccontextmanager
+    async def async_session(cls):
+        session_factory = cls._get_session_factory()
+        async with session_factory() as session:
+            yield session

src/config/_logger.py

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+import os
+
+from loguru import logger
+
+LOG_FILE = os.getenv("LOG_FILE")
+if LOG_FILE:
+    LOG_RETENTION = os.getenv("LOG_RETENTION", "90 days")
+    logger.add(LOG_FILE, retention=LOG_RETENTION)

src/controllers/__init__.py

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+from fastapi import APIRouter
+
+api_router = APIRouter()
+
+__all__ = ["api_router"]
+__version__ = "0.1.0"
+__author__ = "Aryan Jain"

src/models/__init__.py

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+from ._base import Base
+
+__all__ = ["Base"]
+__version__ = "0.1.0"
+__author__ = "Aryan Jain"

src/models/_base.py

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+from sqlalchemy.orm import declarative_base
+
+Base = declarative_base()

src/repositories/__init__.py

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+from ._base_repository import BaseRepository
+
+__all__ = ["BaseRepository"]
+__version__ = "0.1.0"
+__author__ = "Aryan Jain"

src/repositories/_base_repository.py

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+from contextlib import asynccontextmanager
+from typing import Any, Dict, Optional, Type, TypeVar
+
+from sqlalchemy import asc, desc
+from sqlalchemy.exc import NoResultFound, SQLAlchemyError
+from sqlalchemy.future import select
+
+from src.config import DatabaseConfig
+
+T = TypeVar("T")
+
+
+class BaseRepository:
+    def __init__(self, model: Type[T]):
+        self._model = model
+
+    @asynccontextmanager
+    async def get_session(self):
+        async with DatabaseConfig.async_session() as session:
+            try:
+                yield session
+            except SQLAlchemyError as e:
+                await session.rollback()
+                raise e
+
+    async def create(self, **kwargs: Dict[str, Any]):
+        async with self.get_session() as session:
+            instance = self._model(**kwargs)
+            session.add(instance)
+            await session.commit()
+            await session.refresh(instance)
+            return instance
+
+    async def get(self, id: Any):
+        async with self.get_session() as session:
+            result = await session.get(self._model, id)
+            if result is None:
+                raise NoResultFound(f"{self._model.__name__} not found with id {id}")
+            return result
+
+    async def patch(self, id: Any, **kwargs: Dict[str, Any]):
+        async with self.get_session() as session:
+            instance = await session.get(self._model, id)
+            if not instance:
+                raise NoResultFound(f"{self._model.__name__} not found with id {id}")
+            for key, value in kwargs.items():
+                setattr(instance, key, value)
+            await session.commit()
+            await session.refresh(instance)
+            return instance
+
+    async def delete(self, id: Any):
+        async with self.get_session() as session:
+            instance = await session.get(self._model, id)
+            if not instance:
+                raise NoResultFound(f"{self._model.__name__} not found with id {id}")
+            await session.delete(instance)
+            await session.commit()
+            return True
+
+    async def get_all(
+        self,
+        page: int = 1,
+        page_size: int = 10,
+        filter_by: Optional[Dict[str, Any]] = {},
+        order_by: Optional[Dict[str, str]] = {},
+    ):
+        async with self.get_session() as session:
+            offset = (page - 1) * page_size
+            query = (
+                select(self._model)
+                .filter_by(**filter_by)
+                .offset(offset)
+                .limit(page_size)
+            )
+            for field, direction in order_by.items():
+                ordering = asc if direction == "asc" else desc
+                query = query.order_by(ordering(getattr(self._model, field)))
+            result = await session.execute(query)
+            return result.scalars().all()
+
+    async def execute(self, query):
+        async with self.get_session() as session:
+            result = await session.execute(query)
+            return result

src/services/__init__.py

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+__version__ = "0.1.0"
+__author__ = "Aryan Jain"

src/utils/__init__.py

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+__version__ = "0.1.0"
+__author__ = "Aryan Jain"