[main] Slight changes to models to finally make them work

src/models/__init__.py

@@ -1,7 +1,10 @@
+from .base import Base
 from .author import Author
-from .book_category import BookCategory
 from .book import Book
+from .book_category import BookCategory
 from .book_category_link import BookCategoryLink
 from .member import Member
 from .librarian import Librarian
 from .loan import Loan
+
+__all__ = ["Author", "Book", "BookCategory", "BookCategoryLink", "Member", "Librarian", "Loan"]

src/models/author.py

@@ -1,8 +1,7 @@
 from sqlalchemy import Column, Integer, String, TIMESTAMP, UniqueConstraint, func
 from sqlalchemy.orm import relationship
-from sqlalchemy.ext.declarative import declarative_base
 
-Base = declarative_base()
+from .base import Base
 
 
 class Author(Base):
@@ -13,3 +12,6 @@ class Author(Base):
     first_name = Column(String(50), nullable=False)
     last_name = Column(String(50), nullable=False)
     last_updated = Column(TIMESTAMP, nullable=False, server_default=func.now())
+
+    # Reference 'Book' as a string to avoid direct import
+    books = relationship('Book', back_populates='author')

src/models/base.py

@@ -0,0 +1,3 @@
+from sqlalchemy.ext.declarative import declarative_base
+
+Base = declarative_base()

src/models/book.py

@@ -2,12 +2,8 @@ import enum
 
 from sqlalchemy import Column, Integer, String, TIMESTAMP, Text, ForeignKey, Enum, UniqueConstraint, func
 from sqlalchemy.orm import relationship
-from sqlalchemy.ext.declarative import declarative_base
 
-from .author import Author
-from .book_category import BookCategory
-
-Base = declarative_base()
+from .base import Base
 
 
 class BookStatusEnum(enum.Enum):
@@ -15,6 +11,7 @@ class BookStatusEnum(enum.Enum):
     borrowed = 'borrowed'
     reserved = 'reserved'
 
+
 class Book(Base):
     __tablename__ = 'book'
     __table_args__ = (UniqueConstraint('isbn'),)
@@ -29,4 +26,5 @@ class Book(Base):
     created_at = Column(TIMESTAMP, nullable=False, server_default=func.now())
     last_updated = Column(TIMESTAMP, nullable=False, server_default=func.now())
 
-    author = relationship('Author', backref='books')
+    # Reference 'Author' as a string to avoid direct import
+    author = relationship('Author', back_populates='books')

src/models/book_category.py

@@ -1,9 +1,7 @@
 from sqlalchemy import Column, Integer, String, TIMESTAMP, ForeignKey, UniqueConstraint, func
 from sqlalchemy.orm import relationship
-from sqlalchemy.ext.declarative import declarative_base
-
-Base = declarative_base()
 
+from .base import Base
 
 class BookCategory(Base):
     __tablename__  = 'book_category'

src/models/book_category_link.py

@@ -1,12 +1,9 @@
 from sqlalchemy import Column, Integer, ForeignKey
 from sqlalchemy.orm import relationship
-from sqlalchemy.ext.declarative import declarative_base
-
 
 from .book import Book
 from .book_category import BookCategory
-
-Base = declarative_base()
+from .base import Base
 
 class BookCategoryLink(Base):
     __tablename__ = 'book_category_link'

src/models/librarian.py

@@ -2,10 +2,8 @@ import enum
 
 from sqlalchemy import Column, Integer, String, TIMESTAMP, Text, ForeignKey, Enum, UniqueConstraint, func
 from sqlalchemy.orm import relationship
-from sqlalchemy.ext.declarative import declarative_base
 
-
-Base = declarative_base()
+from .base import Base
 
 
 class LibrarianStatusEnum(enum.Enum):

src/models/loan.py

@@ -2,14 +2,12 @@ import enum
 
 from sqlalchemy import Column, Integer, String, TIMESTAMP, Text, ForeignKey, Enum, UniqueConstraint, Float, func
 from sqlalchemy.orm import relationship
-from sqlalchemy.ext.declarative import declarative_base
 
+from .base import Base
 from .book import Book
 from .member import Member
 from .librarian import Librarian
 
-Base = declarative_base()
-
 
 class LoanStatusEnum(enum.Enum):
     borrowed = 'borrowed'

src/models/member.py

@@ -2,13 +2,14 @@ import enum
 
 from sqlalchemy import Column, Integer, String, TIMESTAMP, Text, ForeignKey, Enum, UniqueConstraint, func
 from sqlalchemy.orm import relationship
-from sqlalchemy.ext.declarative import declarative_base
+
+from .base import Base
+
 
 class MemberStatusEnum(enum.Enum):
     active = 'active'
     inactive = 'inactive'
 
-Base = declarative_base()
 
 class Member(Base):
     __tablename__  = 'member'