about to really rewrite the swapping sub books, so committing what we have that partially works

main.py

@@ -92,6 +92,26 @@ class Book(db.Model):
     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" )
     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" )
 
+    def IsParent(self):
+        if len(self.child_ref):
+            return True
+        else:
+            return False
+
+    def IsChild(self):
+        if len(self.parent_ref):
+            return True
+        else:
+            return False
+
+    def FirstSubBookId(self):
+		# need to work out the first sub book and return an id?
+        return False
+
+    def LastSubBookId(self):
+		# need to work out the last sub book and return an id?
+        return False
+
     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 )
 
@@ -114,9 +134,6 @@ class BookSchema(ma.SQLAlchemyAutoSchema):
     child_ref = ma.Nested(Book_Sub_Book_LinkSchema, many=True)
     class Meta: model = Book
 
-#
-# To be completed
-#
 class BookForm(FlaskForm):
     id = HiddenField()
     title = StringField('Title:', [validators.DataRequired()])
@@ -175,8 +192,12 @@ def books_for_series(id):
             book1_s = book_schema.dump( book1 )
 			# only have to check if we are a parent, as if we were a child, we
 			# do not have a button to even press to cause this condition
-            if len(book1_s['child_ref']):
-                print( "we want to swap a parent book" )
+            if book1.IsParent():
+                print( book1_s )
+                bsl_of_first_sub_of_b1=Book_Sub_Book_Link.query.filter(Book_Sub_Book_Link.book_id==bid,Book_Sub_Book_Link.sub_book_num==book1_s['child_ref'][0]['sub_book_num'] ).all()
+                print( bsl_of_first_sub_of_b1 )
+                bid=bsl_of_first_sub_of_b1[0].sub_book_id
+                print( "we want to swap a parent book - we have {} subbooks, and subbook in series is: {}".format( len(book1_s['child_ref']), bid ))
             bsl1=Book_Series_Link.query.filter(Book_Series_Link.series_id==id, Book_Series_Link.book_id==bid).all()
             print( bsl1[0].book_num )
             if dir == "up":
@@ -190,13 +211,11 @@ def books_for_series(id):
             book2 = Book.query.get(bsl2[0].book_id)
             book2_s = book_schema.dump( book2 )
             print( book2_s )
-            if len(book2_s['child_ref']):
-                print( "swapping with a parent book!" )
             if len(book2_s['parent_ref']):
-                print( "swapping with a parent book! (and the 'next' book is a child book)" )
-            bsl2[0].book_num=bsl1[0].book_num
-            bsl1[0].book_num=other_bn
-            db.session.commit()
+                print( "swapping with a parent book! (as the next book in the series is a child book)" )
+#            bsl2[0].book_num=bsl1[0].book_num
+#            bsl1[0].book_num=other_bn
+#            db.session.commit()
     books = Book.query.join(Book_Series_Link).filter(Book_Series_Link.series_id==id).all()
     series = Series.query.get(id)
     return render_template("books_for_series.html", books=books, series=series)
@@ -206,12 +225,9 @@ def book(id):
     book = Book.query.get(id)
     book_s = book_schema.dump(book)
 
-       ######
-    ###
-    ### okay, this manual hacking of sub_book is currently going to be needed, because in the jinja2 I want to list the book, and more than just the id number of the sub_book, I want the details... (sub_book_schema needs a book relationship BUT, dependencies mean I can't define a book schema inside sub_book schema, and I am definitely not sure how to join it anyway... for another time.
-    ###
-    #####
-    # force sub books for jinja2 to be able to use
+    ####################################
+    # force sub books for jinja2 to be able to use (ORM is not giving all the details
+    ####################################
     subs = db.engine.execute ( "select bsb.book_id, bsb.sub_book_id, bsb.sub_book_num, book.title, book.rating, book.year_published, book.notes, bal.author_id as author_id, author.surname||', '||author.firstnames as author from book_sub_book_link bsb, book, book_author_link bal, author where bsb.book_id = {} and book.id = bsb.sub_book_id and book.id = bal.book_id and bal.author_id = author.id".format( id ) )
     sub_book=[]
     for row in subs: