Merge branch '2025-dataclasses'

Author: egges

2025/dataclasses/books.db

@@ -0,0 +1,44 @@
+import secrets
+
+import uvicorn
+from fastapi import FastAPI, HTTPException
+from pydantic import BaseModel
+
+app = FastAPI()
+
+
+class Book(BaseModel):
+    title: str
+    author: str
+    pages: int = 0
+
+
+books_db: dict[str, Book] = {}
+
+
+def generate_id() -> str:
+    # Generate a 24-character hex string (like MongoDB ObjectID)
+    return secrets.token_hex(12)
+
+
+@app.post("/books/")
+def create_book(book: Book):
+    book_id = generate_id()
+    books_db[book_id] = book
+    return {"id": book_id, "book": book}
+
+
+@app.get("/books/{book_id}")
+def get_book(book_id: str):
+    if book_id not in books_db:
+        raise HTTPException(status_code=404, detail="Book not found")
+    return {"id": book_id, "book": books_db[book_id]}
+
+
+@app.get("/books/")
+def list_books():
+    return [{"id": book_id, "book": book} for book_id, book in books_db.items()]
+
+
+if __name__ == "__main__":
+    uvicorn.run(app, host="0.0.0.0", port=8000)

2025/dataclasses/fastapi_example.py

@@ -0,0 +1,70 @@
+import secrets
+from dataclasses import dataclass, field
+
+import uvicorn
+from fastapi import FastAPI, HTTPException
+from pydantic import BaseModel
+
+app = FastAPI()
+
+# --- DOMAIN MODEL ---
+
+
+def generate_id() -> str:
+    return secrets.token_hex(12)
+
+
+@dataclass
+class Book:
+    title: str
+    author: str
+    pages: int = 0
+    id: str = field(default_factory=generate_id)
+
+
+# --- Pydantic MODELS for API ---
+
+
+class BookCreate(BaseModel):
+    title: str
+    author: str
+    pages: int = 0
+
+
+class BookResponse(BaseModel):
+    id: str
+    title: str
+    author: str
+    pages: int
+
+
+# --- FAKE DB ---
+
+books_db: dict[str, Book] = {}
+
+
+# --- ROUTES ---
+
+
+@app.post("/books/", response_model=BookResponse)
+def create_book(book_data: BookCreate):
+    book = Book(**book_data.dict())  # ID is generated automatically
+    books_db[book.id] = book
+    return BookResponse(**book.__dict__)
+
+
+@app.get("/books/{book_id}", response_model=BookResponse)
+def get_book(book_id: str):
+    book = books_db.get(book_id)
+    if not book:
+        raise HTTPException(status_code=404, detail="Book not found")
+    return BookResponse(**book.__dict__)
+
+
+@app.get("/books/", response_model=list[BookResponse])
+def list_books():
+    return [BookResponse(**book.__dict__) for book in books_db.values()]
+
+
+if __name__ == "__main__":
+    uvicorn.run(app, host="0.0.0.0", port=8000)

2025/dataclasses/fastapi_model_example.py

@@ -0,0 +1,74 @@
+import secrets
+
+import uvicorn
+from fastapi import FastAPI, HTTPException
+from pydantic import BaseModel, dataclasses
+
+app = FastAPI()
+
+# --- DOMAIN MODEL (Pydantic Dataclass) ---
+
+
+def generate_id() -> str:
+    return secrets.token_hex(12)
+
+
+@dataclasses.dataclass
+class Book:
+    title: str
+    author: str
+    pages: int = 0
+    id: str = dataclasses.Field(default_factory=generate_id)
+
+
+# --- API MODELS (Pydantic BaseModels) ---
+
+
+class BookCreate(BaseModel):
+    title: str
+    author: str
+    pages: int = 0
+
+    class Config:
+        from_attributes = True
+
+
+class BookResponse(BaseModel):
+    id: str
+    title: str
+    author: str
+    pages: int
+
+    class Config:
+        from_attributes = True
+
+
+# --- FAKE IN-MEMORY DB ---
+
+books_db: dict[str, Book] = {}
+
+# --- ROUTES ---
+
+
+@app.post("/books/", response_model=BookResponse)
+def create_book(book_data: BookCreate):
+    book = Book(**book_data.model_dump())
+    books_db[book.id] = book
+    return BookResponse.model_validate(book)
+
+
+@app.get("/books/{book_id}", response_model=BookResponse)
+def get_book(book_id: str):
+    book = books_db.get(book_id)
+    if not book:
+        raise HTTPException(status_code=404, detail="Book not found")
+    return BookResponse.model_validate(book)
+
+
+@app.get("/books/", response_model=list[BookResponse])
+def list_books():
+    return [BookResponse.model_validate(book) for book in books_db.values()]
+
+
+if __name__ == "__main__":
+    uvicorn.run(app, host="0.0.0.0", port=8000)

2025/dataclasses/fastapi_model_example_v2.py

@@ -0,0 +1,105 @@
+import secrets
+
+import uvicorn
+from fastapi import Depends, FastAPI, HTTPException
+from pydantic import BaseModel
+from sqlalchemy import Integer, String, create_engine
+from sqlalchemy.orm import (
+    DeclarativeBase,
+    Mapped,
+    Session,
+    mapped_column,
+    sessionmaker,
+)
+
+# --- Database setup ---
+
+DATABASE_URL = "sqlite:///./books.db"
+engine = create_engine(DATABASE_URL, connect_args={"check_same_thread": False})
+
+SessionLocal = sessionmaker(bind=engine, autoflush=False)
+
+
+# declarative base class
+class Base(DeclarativeBase):
+    pass
+
+
+# --- SQLAlchemy ORM model ---
+
+
+class Book(Base):
+    __tablename__ = "books"
+
+    id: Mapped[str] = mapped_column(
+        primary_key=True, default=lambda: secrets.token_hex(12)
+    )
+    title: Mapped[str] = mapped_column(String, nullable=False)
+    author: Mapped[str] = mapped_column(String, nullable=False)
+    pages: Mapped[int] = mapped_column(Integer, default=0)
+
+
+# --- Pydantic models ---
+
+
+class BookCreate(BaseModel):
+    title: str
+    author: str
+    pages: int = 0
+
+
+class BookResponse(BaseModel):
+    id: str
+    title: str
+    author: str
+    pages: int
+
+    class Config:
+        from_attributes = True  # allows conversion from ORM objects
+
+
+# --- Dependency to get a DB session ---
+
+
+def get_db():
+    db = SessionLocal()
+    try:
+        yield db
+    finally:
+        db.close()
+
+
+# --- FastAPI setup ---
+
+app = FastAPI()
+
+# Create tables
+Base.metadata.create_all(bind=engine)
+
+# --- Routes ---
+
+
+@app.post("/books/", response_model=BookResponse)
+def create_book(book_data: BookCreate, db: Session = Depends(get_db)):
+    book = Book(**book_data.model_dump())
+    db.add(book)
+    db.commit()
+    db.refresh(book)
+    return book
+
+
+@app.get("/books/{book_id}", response_model=BookResponse)
+def get_book(book_id: str, db: Session = Depends(get_db)):
+    book = db.get(Book, book_id)
+    if not book:
+        raise HTTPException(status_code=404, detail="Book not found")
+    return book
+
+
+@app.get("/books/", response_model=list[BookResponse])
+def list_books(db: Session = Depends(get_db)):
+    return db.query(Book).all()
+
+
+if __name__ == "__main__":
+    uvicorn.run(app, host="0.0.0.0", port=8000)

2025/dataclasses/fastapi_sqlalchemy.py

@@ -0,0 +1,45 @@
+from pydantic import BaseModel, ValidationError, validator
+from pydantic.dataclasses import dataclass
+
+
+@dataclass
+class Book:
+    title: str
+    pages: int
+
+    @validator("pages")
+    def pages_must_be_positive(cls, v: int):
+        if v < 0:
+            raise ValueError("Pages must be a positive integer")
+        return v
+
+
+class Author(BaseModel):
+    name: str
+    age: int
+
+    @validator("age")
+    def age_must_be_positive(cls, v: int):
+        if v < 0:
+            raise ValueError("Age must be a positive integer")
+        return v
+
+
+def main() -> None:
+    # Valid input
+    book = Book(title="1984", pages=328)  # pages will be converted to int
+
+    # print(book.model_dump())  # {'title': '1984', 'pages': 328}
+
+    # Invalid input – will raise a ValidationError
+    try:
+        bad_book = Book(title="The Hobbit", pages="three hundred")
+    except ValidationError as e:
+        print(e)
+
+    author = Author(name="J.R.R. Tolkien", age=81)
+    print(author.model_dump())  # {'name': 'J.R.R. Tolkien', 'age': 81}
+
+
+if __name__ == "__main__":
+    main()

2025/dataclasses/pydantic_dc.py

@@ -0,0 +1,10 @@
+[project]
+name = "dataclasses_vs_pydantic"
+version = "0.1.0"
+requires-python = ">=3.13"
+dependencies = [
+    "fastapi>=0.115.12",
+    "pydantic>=2.11.4",
+    "sqlalchemy>=2.0.41",
+    "uvicorn>=0.34.2",
+]