[storm] problem with many to one relationship

[peter websdell]

Hello again,
You recommendation fixed my previous problem, thank you. I now have a new
problem. I've been staring at the code for about 2 hours now, and cannot see
what is wrong. Please don't think I'm asking for help without trying first,
I'm just new to this, and fairly new to python, so my skills are not up to
speed.

SQL
http://pastebin.com/m475383da

Python
http://pastebin.com/m59ef0556

Output
http://pastebin.com/m43bdb79d

Can you see what the problem here is. I'm stumped.

Cheers,
Pete.



2009/9/18 James Henstridge <james at jamesh.id.au>

> On Fri, Sep 18, 2009 at 12:07 AM, peter websdell
> <flyingdeckchair at googlemail.com> wrote:
> > Hello all,
> > Can anyone help me see what I'm doing wrong here?
> >
> > SQL
> > CREATE TABLE IF NOT EXISTS `author` (
> >   `id` int(8) NOT NULL auto_increment,
> >   `first_name` varchar(32) NOT NULL,
> >   `last_name` varchar(32) NOT NULL,
> >   PRIMARY KEY  (`id`)
> > ) ENGINE=MyISAM  DEFAULT CHARSET=latin1 AUTO_INCREMENT=3 ;
> >
> > CREATE TABLE IF NOT EXISTS `book` (
> >   `id` int(8) NOT NULL auto_increment,
> >   `title` varchar(64) NOT NULL,
> >   `author_id` int(8) NOT NULL,
> >   PRIMARY KEY  (`id`)
> > ) ENGINE=MyISAM  DEFAULT CHARSET=latin1 AUTO_INCREMENT=3 ;
> >
> > PYTHON
> > database = create_database("mysql://uname:password@localhost:3306/DB")
> > store = Store(database)
> > class Book(Storm):
> >     __storm_table__ = "book"
> >     id=Int(primary=True)
> >     title = Unicode()
> >     author_id=Int()
> >     author = Reference(author_id,"Author.id")
> >     def __init__(self, title):
> >         self.title = title
> >
> > class Author(Storm):
> >     __storm_table__="author"
> >     id=Int(primary=True)
> >     first_name=Unicode()
> >     last_name=Unicode()
> >     books= ReferenceSet(id,"Book.id")
>
> ^^^ This is the bug.  You've set up your one to many relationship
> between Author's primary key and Book's primary key, rather than with
> Book's foreign key pointing back to Author.  Try changing it to the
> following:
>
>    books = ReferenceSet(id, Book.author_id)
>
> >     def __init__(self, first_name, last_name):
> >         self.first_name = first_name
> >         self.last_name = last_name
> >
> > dog=store.add(Book(u"Dog Called Demolition"))
> > rankin=store.add(Author(u"Robert", u"Rankin"))
> > store.flush()
> > print "rankin id is %i" % (rankin.id)
> > print "dog id is %i" % (dog.id)
> > rankin.books.add(dog)
>
> Due to the above bug, this statement will attempt to set dog.id to
> rankin.id.  dog.author_id remains None, which is why dog.author is
> also None.
>
> > print "rankin book 1 = %s" %(rankin.books.one().title)
> > print "dog author name = %s" % (dog.author.first_name)
> > The error given is:
> > Traceback (most recent call last):
> >   File "models.py", line 33, in <module>
> >     print "dog author name = %s" % (dog.author.first_name)
> > AttributeError: 'NoneType' object has no attribute 'first_name'
> >
> > I thought storm should automatically assign the author_id to the book
> object
> > when the book is added to the Author-object "books" set.
>
> It should.  If it doesn't with the above bug fixed, please tell us.
>
> James.
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: https://lists.ubuntu.com/archives/storm/attachments/20090918/c0d21868/attachment-0002.htm