Created models for genres

library_service/models/db/book.py

@@ -1,10 +1,11 @@
 from typing import List, Optional, TYPE_CHECKING
 from sqlmodel import SQLModel, Field, Relationship
 from ..dto.book import BookBase
-from .links import AuthorBookLink
+from .links import AuthorBookLink, GenreBookLink
 
 if TYPE_CHECKING:
     from .author import Author
+    from .genre import Genre
 
 class Book(BookBase, table=True):
     id: Optional[int] = Field(default=None, primary_key=True, index=True)
@@ -12,3 +13,7 @@ class Book(BookBase, table=True):
         back_populates="books",
         link_model=AuthorBookLink
     )
+    genres: List["Genre"] = Relationship(
+        back_populates="books",
+        link_model=GenreBookLink
+    )