okay removed sub_book as a formal db.relationship, its too confusing, using raw sql for now. Still need to ensure ordering of sub_books based on book_id, sub_book_num AND need to pass enough sub_book fields that can vary so that jinja2 can show all subs of a book when editing any of them

main.py

@@ -22,15 +22,6 @@ book_publisher_link = db.Table('book_publisher_link', db.Model.metadata,
     db.Column('publisher_id', db.Integer, db.ForeignKey('publisher.id'))
 )
 
-class Book_Sub_Book_Link(db.Model):
-    __tablename__ = 'book_sub_book_link'
-    book_id = db.Column( db.Integer, db.ForeignKey('book.id'), primary_key=True)
-    sub_book_id = db.Column( db.Integer, db.ForeignKey('book.id'), primary_key=True)
-    sub_book_num = db.Column( db.Integer )
-
-    def __repr__(self):
-        return "<book_id: {}, sub_book_id: {}, sub_book_num>".format(self.book_id, self.sub_book_id, self.sub_book_num )
-
 class Book(db.Model):
     id = db.Column(db.Integer, unique=True, nullable=False, primary_key=True)
     title = db.Column(db.String(100), unique=True, nullable=False)
@@ -46,11 +37,6 @@ class Book(db.Model):
 
     author = db.relationship('Author', secondary=book_author_link)
     publisher = db.relationship('Publisher', secondary=book_publisher_link)
-#    sub_book = db.relationship('Book', secondary="book_sub_book_link",
-#       primaryjoin="Book.id == Book_Sub_Book_Link.book_id",
-#       secondaryjoin="Book.id == Book_Sub_Book_Link.sub_book_id",
-#       backref="parent_book",  
-#    )
 
     def __repr__(self):
         return "<id: {}, title: {}, year_published: {}, rating: {}, condition: {}, owned: {}, covertype: {}, notes: {}, blurb: {}, created: {}, modified: {}, publisher: {}>".format(self.title, self.id, self.year_published, self.rating, self.condition, self.owned, self.covertype, self.notes, self.blurb, self.created, self.modified, self.publisher )
@@ -85,42 +71,47 @@ class PublisherSchema(ma.SQLAlchemyAutoSchema):
         include_relationships = True
         load_instance = True
 
-class Book_Sub_Book_Link(ma.SQLAlchemyAutoSchema):
+class BookSchema(ma.SQLAlchemyAutoSchema):
+    author = ma.Nested(AuthorSchema, many=True)
+    publisher = ma.Nested(PublisherSchema, many=True)
     class Meta:
-        model = Book_Sub_Book_Link
+        model = Book
         include_relationships = True
         load_instance = True
 
-#class BookSchema(ma.SQLAlchemyAutoSchema):
-#    class Meta:
-#        model = Book
-#        include_relationships = True
-#        load_instance = True
-
 author_schema = AuthorSchema()
 publisher_schema = PublisherSchema()
-book_sub_book_link_schema = Book_Sub_Book_Link()
-#book_schema = BookSchema()
+book_schema = BookSchema()
 
 ####################################### ROUTES #######################################
 @app.route("/books", methods=["GET"])
 def books():
     if request.form:
         print(request.form)
-#    books = Book.query.all()
-	#### quick hack - lets just return all the books not in the first 6, but should be those that are not in list of book_id's from book_sub_book_link
-    books = Book.query.filter( ~ Book.id.in_([0, 1, 2, 3, 4, 5, 6]) ).all()
+
+    books = Book.query.all()
+	# want to get sub book info and patch it into the books object to at least reference sub_book_num and parent_book, 
+	# then per book in jinja2, slide it into the right aprt of the table with the right markup to show its a sub book
+    subs = db.engine.execute ( "select * from book_sub_book_link" )
+    for row in subs:
+       index = next((i for i, item in enumerate(books) if item.id == row.sub_book_id), -1)
+       books[index].parent_id = row.book_id
+       books[index].sub_book_num = row.sub_book_num
+
     return render_template("books.html", books=books)
 
 @app.route("/book/<id>", methods=["GET"])
 def book(id):
     book = Book.query.get(id)
     book_s = book_schema.dump(book)
+
+	# force sub books for jinja2 to be able to use
     subs = db.engine.execute ( "select book_id, sub_book_id, sub_book_num from book_sub_book_link where book_id = " + id )
     sub_book=[]
     for row in subs:
        sub_book.append( { 'sub_book_id': row.sub_book_id, 'sub_book_num': row.sub_book_num } )
     book_s['sub_book'] = sub_book
+    print( book_s )
 
     return render_template("books.html", books=book_s )
 

templates/books.html

@@ -21,7 +21,11 @@
 	  <tbody>
       {% for book in books %}
         <tr>
-		  <td data-sort="{{book.id}}"><a href="/book/{{book.id}}">{{book.title}}</a></td>
+		  {% if book.sub_book_num is defined %}
+		  	<td data-sort="{{book.id}}"><a href="/book/{{book.id}}">&nbsp;&nbsp;&nbsp;&nbsp;{{book.title}}</a></td>
+		  {% else %}
+		  	<td data-sort="{{book.id}}"><a href="/book/{{book.id}}">{{book.title}}</a></td>
+		  {% endif %}
 		  <td>{{ book.author[0]['surname'] }}, {{book.author[0]['firstnames']}}</td>
 		  <td>{{ book.publisher[0]['name']}}</td>
 		  <td align="center">
@@ -42,6 +46,9 @@
 	{% else %}
 	<h3>Book</h1>
       <p>{{books.title}}, {{ books.author[0]['surname'] }}, {{books.author[0]['firstnames']}} </p>
+	  {% if books.sub_book is defined %}
+		  <p>sub_book is defined: {{books.sub_book}}</p>
+	  {% endif %}
 	{% endif %}
 
 	<!-- code to get bootstrap & bootstrap datatable to work -->