Global refactoring of the project to use poetry and implement tests,

fixing bugs, changing the handling of dto and db models, preparing to
add new functionality

library_service/routers/authors.py

@@ -0,0 +1,80 @@
+from fastapi import APIRouter, Depends, HTTPException
+from sqlmodel import Session, select
+
+from library_service.settings import get_session
+from library_service.models.db import Author, AuthorBookLink, Book, AuthorWithBooks
+from library_service.models.dto import (
+    AuthorCreate, AuthorUpdate, AuthorRead,
+    AuthorList, BookRead
+)
+
+router = APIRouter(prefix="/authors", tags=["authors"])
+
+# Create an author
+@router.post("/", response_model=AuthorRead)
+def create_author(author: AuthorCreate, session: Session = Depends(get_session)):
+    db_author = Author(**author.model_dump())
+    session.add(db_author)
+    session.commit()
+    session.refresh(db_author)
+    return AuthorRead(**db_author.model_dump())
+
+# Read authors
+@router.get("/", response_model=AuthorList)
+def read_authors(session: Session = Depends(get_session)):
+    authors = session.exec(select(Author)).all()
+    return AuthorList(
+        authors=[AuthorRead(**author.model_dump()) for author in authors],
+        total=len(authors)
+    )
+
+# Read an author with their books
+@router.get("/{author_id}", response_model=AuthorWithBooks)
+def get_author(author_id: int, session: Session = Depends(get_session)):
+    author = session.get(Author, author_id)
+    if not author:
+        raise HTTPException(status_code=404, detail="Author not found")
+
+    books = session.exec(
+        select(Book)
+        .join(AuthorBookLink)
+        .where(AuthorBookLink.author_id == author_id)
+    ).all()
+
+    book_reads = [BookRead(**book.model_dump()) for book in books]
+
+    author_data = author.model_dump()
+    author_data['books'] = book_reads
+
+    return AuthorWithBooks(**author_data)
+
+# Update an author
+@router.put("/{author_id}", response_model=AuthorRead)
+def update_author(
+    author_id: int,
+    author: AuthorUpdate,
+    session: Session = Depends(get_session)
+):
+    db_author = session.get(Author, author_id)
+    if not db_author:
+        raise HTTPException(status_code=404, detail="Author not found")
+
+    update_data = author.model_dump(exclude_unset=True)
+    for field, value in update_data.items():
+        setattr(db_author, field, value)
+
+    session.commit()
+    session.refresh(db_author)
+    return AuthorRead(**db_author.model_dump())
+
+# Delete an author
+@router.delete("/{author_id}", response_model=AuthorRead)
+def delete_author(author_id: int, session: Session = Depends(get_session)):
+    author = session.get(Author, author_id)
+    if not author:
+        raise HTTPException(status_code=404, detail="Author not found")
+
+    author_read = AuthorRead(**author.model_dump())
+    session.delete(author)
+    session.commit()
+    return author_read