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/models/db/__init__.py

@@ -0,0 +1,7 @@
+from .author import Author
+from .book import Book
+from .links import AuthorBookLink, AuthorWithBooks, BookWithAuthors
+
+__all__ = [
+    'Author', 'Book', 'AuthorBookLink', 'AuthorWithBooks', 'BookWithAuthors'
+]

library_service/models/db/author.py

@@ -0,0 +1,14 @@
+from typing import List, Optional, TYPE_CHECKING
+from sqlmodel import SQLModel, Field, Relationship
+from ..dto.author import AuthorBase
+from .links import AuthorBookLink
+
+if TYPE_CHECKING:
+    from .book import Book
+
+class Author(AuthorBase, table=True):
+    id: Optional[int] = Field(default=None, primary_key=True, index=True)
+    books: List["Book"] = Relationship(
+        back_populates="authors",
+        link_model=AuthorBookLink
+    )

library_service/models/db/book.py

@@ -0,0 +1,14 @@
+from typing import List, Optional, TYPE_CHECKING
+from sqlmodel import SQLModel, Field, Relationship
+from ..dto.book import BookBase
+from .links import AuthorBookLink
+
+if TYPE_CHECKING:
+    from .author import Author
+
+class Book(BookBase, table=True):
+    id: Optional[int] = Field(default=None, primary_key=True, index=True)
+    authors: List["Author"] = Relationship(
+        back_populates="books",
+        link_model=AuthorBookLink
+    )

library_service/models/db/links.py

@@ -0,0 +1,15 @@
+from sqlmodel import SQLModel, Field
+from typing import List
+
+from library_service.models.dto.author import AuthorRead
+from library_service.models.dto.book import BookRead
+
+class AuthorBookLink(SQLModel, table=True):
+    author_id: int | None = Field(default=None, foreign_key="author.id", primary_key=True)
+    book_id: int | None = Field(default=None, foreign_key="book.id", primary_key=True)
+
+class AuthorWithBooks(AuthorRead):
+    books: List[BookRead] = Field(default_factory=list)
+
+class BookWithAuthors(BookRead):
+    authors: List[AuthorRead] = Field(default_factory=list)