okay, using ORM, the book_sub_book_link table is actually linked, it is also being used to force the ordering of the quert - although its probably not needed, as the datatables sort can do it by using sub_book_num and parent_id... Those values are still being put in by hand, so need to think about the parent_id bit... we need it to get the sorting to work. I think the sub_book_num would now be there in the normal book.dump() if I try to put it there -- would need to make sure the appropriate Schema is used of course

main.py

@@ -27,6 +27,15 @@ book_genre_link = db.Table('book_genre_link', db.Model.metadata,
     db.Column('genre_id', db.Integer, db.ForeignKey('genre_lst.id'))
 )
 
+class Book_Sub_Book_Link(db.Model):
+    __tablename__ = "book_sub_book_link"
+    book_id = db.Column(db.Integer, db.ForeignKey('book.id'), unique=True, nullable=False, primary_key=True)
+    sub_book_id = db.Column(db.Integer, db.ForeignKey('book.id'), unique=True, nullable=False, 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)
@@ -43,6 +52,7 @@ class Book(db.Model):
     author = db.relationship('Author', secondary=book_author_link)
     publisher = db.relationship('Publisher', secondary=book_publisher_link)
     genre = db.relationship('Genre_Lst', secondary=book_genre_link )
+    subs = db.relationship('Book_Sub_Book_Link', secondary=Book_Sub_Book_Link.__table__, primaryjoin="Book.id==Book_Sub_Book_Link.sub_book_id", secondaryjoin="Book.id==Book_Sub_Book_Link.book_id" )
 
     def __repr__(self):
         return "<id: {}, author: {}, title: {}, year_published: {}, rating: {}, condition: {}, owned: {}, covertype: {}, notes: {}, blurb: {}, created: {}, modified: {}, publisher: {}>".format(self.id, self.author, self.title, self.year_published, self.rating, self.condition, self.owned, self.covertype, self.notes, self.blurb, self.created, self.modified, self.publisher )
@@ -89,10 +99,17 @@ class Genre_LstSchema(ma.SQLAlchemyAutoSchema):
         include_relationships = True
         load_instance = True
 
+class Book_Sub_Book_LinkSchema(ma.SQLAlchemyAutoSchema):
+    class Meta:
+        model = Book_Sub_Book_Link
+        include_relationships = True
+        load_instance = True
+
 class BookSchema(ma.SQLAlchemyAutoSchema):
     author = ma.Nested(AuthorSchema, many=True)
     publisher = ma.Nested(PublisherSchema, many=True)
     genre = ma.Nested(Genre_LstSchema, many=True)
+    subs = ma.Nested(Book_Sub_Book_LinkSchema, many=True)
     class Meta:
         model = Book
         include_relationships = True
@@ -107,7 +124,10 @@ def books():
     if request.form:
         print(request.form)
 
-    books = Book.query.all()
+### DDP: this fails... also, maybe we use ORM to build a parent_book (and I am child #4) and child_books???
+#    books = Book.query.all()
+    books = Book.query.outerjoin(Book_Sub_Book_Link, Book.id==Book_Sub_Book_Link.book_id).order_by(Book.id, Book_Sub_Book_Link.sub_book_num).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" )
@@ -137,6 +157,9 @@ def book(id):
 
     book_s['sub_book'] = sub_book
 
+    print( book.genre )
+    print( book.subs )
+
     return render_template("books.html", books=book_s, subs=sub_book )
 
 @app.route("/authors", methods=["GET"])