rewrote to remove parent_ref and just use parent from ORM, added POST for book/id route, so we can now error on delete and save title only - baby steps -- with alert/message feedback, and also removed debugs

main.py

@@ -89,10 +89,11 @@ class Book(db.Model):
     created = db.Column(db.Date)
     modified = db.Column(db.Date)
 
-    parent_ref = 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" )
+    # take actual parent book as there is no real associated sub_book_num data and can just use it
+    parent = db.relationship('Book', 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" )
+    # but use child_ref as sub_book_num is per book, and I can't connect an empty array of sub_book_nums to a child book array in "child"
     child_ref = db.relationship('Book_Sub_Book_Link', secondary=Book_Sub_Book_Link.__table__, primaryjoin="Book.id==Book_Sub_Book_Link.book_id", secondaryjoin="Book.id==Book_Sub_Book_Link.sub_book_id" )
 
-    parent = db.relationship('Book', 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 IsParent(self):
         if len(self.child_ref):
@@ -101,7 +102,7 @@ class Book(db.Model):
             return False
 
     def IsChild(self):
-        if len(self.parent_ref):
+        if len(self.parent):
             return True
         else:
             return False
@@ -127,7 +128,6 @@ class Book(db.Model):
             return 1
 
     def MoveBookInSeries( self, series_id, amt ):
-        print( "Moving {} by {}".format( self.title, amt ) )
         if self.IsParent():
             tmp_book=book_schema.dump(self)
             for book in tmp_book['child_ref']:
@@ -158,7 +158,6 @@ class BookSchema(ma.SQLAlchemyAutoSchema):
     genre = ma.Nested(GenreSchema, many=True)
     loan = ma.Nested(LoanSchema, many=True)
     series = ma.Nested(SeriesSchema, many=True)
-    parent_ref = ma.Nested(Book_Sub_Book_LinkSchema, many=True)
     child_ref = ma.Nested(Book_Sub_Book_LinkSchema, many=True)
     class Meta: model = Book
 
@@ -175,6 +174,8 @@ class BookForm(FlaskForm):
     rating = SelectField( 'rating',  choices=[(c.id, c.name) for c in Rating.query.order_by('id')] )
     notes = TextAreaField('Notes:')
     blurb = TextAreaField('Blurb:')
+    submit = SubmitField('Save' )
+    delete = SubmitField('Delete' )
 
 
 # allow jinja2 to call this python function
@@ -208,8 +209,9 @@ def GetBookIdFromBookSubBookLinkByIdAndSubBookNum( book_id, sub_book_num ):
 def books():
     books = Book.query.all()
 
-    # ignore ORM, its too slow.  Just select sub_book data and hand add it to
-    # the books object, and use it in jinja2 to indent/order the books/sub books
+    # ignore ORM, the sub_book_num comes from the link, but does not have any attached data, so can't tell which book it connects to.  
+    # Just select sub_book data and hand add it to the books object, and use it in jinja2 to indent/order the books/sub books
+    # This data is used to sort/indent subbooks
     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)
@@ -262,7 +264,7 @@ def books_for_series(id):
             
                 # if book2 is a sub book, then we need its parent as book2 instead, as we have to move the whole book as one
                 if book2.IsChild():
-                   book2 = Book.query.get( book2.parent_ref[0].book_id )
+                   book2 = Book.query.get( book2.parent[0].id )
 
                 # By here: book1 is parent or normal book we are swapping with book2 which is parent or normal book
                 b1_numsb = book1.NumSubBooks()
@@ -287,7 +289,6 @@ def books_for_series(id):
 
 @app.route("/subbooks_for_book/<id>", methods=["GET", "POST"])
 def subbooks_for_book(id):
-    print( "called subbooks_for_book: {}".format(id) )
     if request.method == 'POST':
         if 'move_button' in request.form:
             # split form's pressed move_button to yield: dir ("up" or "down") and bid1 = book_id of subbook 
@@ -325,9 +326,21 @@ def subbooks_for_book(id):
 
     return render_template("subbooks_for_book.html", sub_books=sub_book, s2=subs )
 
-@app.route("/book/<id>", methods=["GET"])
+@app.route("/book/<id>", methods=["GET", "POST"])
 def book(id):
+    alert="success"
+    message=""
+    book_form = BookForm(request.form)
     book = Book.query.get(id)
+    if request.method == 'POST' and book_form.validate():
+        if 'delete' in request.form:
+            alert="danger"
+            message="Sorry, Deleting unsupported at present"
+        else:
+            book.title = request.form['title']
+            db.session.commit()
+            message="Successfully Updated Book (id={})".format(id)
+
     book_s = book_schema.dump(book)
 
     book_form=BookForm(request.form) 
@@ -340,7 +353,7 @@ def book(id):
     author_list = GetAuthors()
     genre_list = GetGenres()
     publisher_list = GetPublishers()
-    return render_template("book.html", b=book, books=book_s, book_form=book_form, author_list=author_list, publisher_list=publisher_list, genre_list=genre_list )
+    return render_template("book.html", b=book, books=book_s, book_form=book_form, author_list=author_list, publisher_list=publisher_list, genre_list=genre_list, alert=alert, message=message )
 
 @app.route("/", methods=["GET"])
 def main_page():