Solution

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/migrations
+
+# 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
+# Or organize into date-based subdirectories (requires recursive_version_locations = true)
+# file_template = %%(year)d/%%(month).2d/%%(day).2d_%%(hour).2d%%(minute).2d_%%(second).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 tzdata library which can be 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 = sqlite:///db.sqlite3
+
+
+[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 module runner, against the "ruff" module
+# hooks = ruff
+# ruff.type = module
+# ruff.module = ruff
+# ruff.options = check --fix REVISION_SCRIPT_FILENAME
+
+# Alternatively, use the exec runner to execute a binary found on your PATH
+# hooks = ruff
+# ruff.type = exec
+# ruff.executable = 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

db/crud.py

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+from sqlalchemy.orm import Session
+from db import models, schemas
+
+
+def get_books(db: Session, skip: int = 0, limit: int = 100):
+    return db.query(models.Book).offset(skip).limit(limit).all()
+
+
+def create_book(db: Session, book_type: schemas.BookBase):
+    db_book = models.Book(
+        title=book_type.title,
+        summary=book_type.summary,
+        publication_date=book_type.publication_date,
+        author_id=book_type.author_id,
+    )
+    db.add(db_book)
+    db.commit()
+    db.refresh(db_book)
+    return db_book
+
+
+def get_authors(db: Session, skip: int = 0, limit: int = 100):
+    return db.query(models.Author).offset(skip).limit(limit).all()
+
+
+def create_author(db: Session, author_type: schemas.AuthorBase):
+    db_author = models.Author(
+        name=author_type.name,
+        bio=author_type.bio,
+    )
+    db.add(db_author)
+    db.commit()
+    db.refresh(db_author)
+    return db_author
+
+
+def get_author(db: Session, author_id: int):
+    return db.query(models.Author).filter(models.Author.id == author_id).first()
+
+
+def get_books_by_author(db: Session, author_id: int, skip: int = 0, limit: int = 100):
+    return (
+        db.query(models.Book)
+        .filter(models.Book.author_id == author_id)
+        .offset(skip)
+        .limit(limit)
+        .all()
+    )

db/database.py

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+from sqlalchemy import create_engine
+from sqlalchemy.orm import sessionmaker, declarative_base
+
+SQLALCHEMY_DATABASE_URL = "sqlite:///db.sqlite3"
+
+
+engine = create_engine(
+    SQLALCHEMY_DATABASE_URL, connect_args={"check_same_thread": False}
+)
+SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)
+
+Base = declarative_base()

db/main.py

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+from fastapi import FastAPI, Depends, HTTPException
+from sqlalchemy.orm import Session
+from database import SessionLocal, engine, Base
+import crud
+import schemas
+
+Base.metadata.create_all(bind=engine)
+
+app = FastAPI(title="Library Management API")
+
+
+def get_db():
+    db = SessionLocal()
+    try:
+        yield db
+    finally:
+        db.close()
+
+
+@app.post("/authors/", response_model=schemas.Author)
+def create_author_endpoint(author: schemas.AuthorBase, db: Session = Depends(get_db)):
+    return crud.create_author(db, author)
+
+
+@app.get("/authors/", response_model=list[schemas.Author])
+def get_authors_endpoint(
+    skip: int = 0, limit: int = 100, db: Session = Depends(get_db)
+):
+    return crud.get_authors(db, skip, limit)
+
+
+@app.get("/authors/{author_id}", response_model=schemas.Author)
+def get_author_endpoint(author_id: int, db: Session = Depends(get_db)):
+    author = crud.get_author(db, author_id)
+    if not author:
+        raise HTTPException(status_code=404, detail="Author not found")
+    return author
+
+
+@app.post("/authors/{author_id}/books/", response_model=schemas.Book)
+def create_book_endpoint(
+    author_id: int, book: schemas.BookBase, db: Session = Depends(get_db)
+):
+    author = crud.get_author(db, author_id)
+    if not author:
+        raise HTTPException(status_code=404, detail="Author not found")
+    return crud.create_book(db, book, author_id)
+
+
+@app.get("/books/", response_model=list[schemas.Book])
+def get_books_endpoint(skip: int = 0, limit: int = 100, db: Session = Depends(get_db)):
+    return crud.get_books(db, skip, limit)
+
+
+@app.get("/books/by-author/{author_id}", response_model=list[schemas.Book])
+def get_books_by_author_endpoint(
+    author_id: int, skip: int = 0, limit: int = 100, db: Session = Depends(get_db)
+):
+    return crud.get_books_by_author(db, author_id, skip, limit)

db/models.py

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+from sqlalchemy import Integer, Column, String, Date, ForeignKey
+from sqlalchemy.orm import relationship
+
+from db.database import Base
+
+
+class Author(Base):
+    __tablename__ = "authors"
+
+    id = Column(Integer, primary_key=True, index=True)
+    name = Column(String(255), nullable=False, unique=True)
+    bio = Column(String(255))
+    books = relationship("Book", back_populates="author")
+
+
+class Book(Base):
+    __tablename__ = "books"
+    id = Column(Integer, primary_key=True)
+    title = Column(String(255), nullable=False)
+    summary = Column(String(255))
+    publication_date = Column(Date)
+    author_id = Column(Integer, ForeignKey("authors.id"))
+    author = relationship("Author", back_populates="books")

db/schemas.py

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+from datetime import date
+from typing import Optional
+
+from pydantic import BaseModel
+
+
+class BookBase(BaseModel):
+    title: str
+    summary: Optional[str]
+    publication_date: Optional[date]
+    author_id: int
+
+
+class Book(BookBase):
+    id: int
+
+    class Config:
+        orm_mode = True
+
+
+class AuthorBase(BaseModel):
+    name: str
+    bio: str
+
+
+class Author(AuthorBase):
+    id: int
+    books: list[Book] = []
+
+    class Config:
+        orm_mode = True

migrations/README

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+Generic single-database configuration.