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Re: How can I use Flex to access foreign-keyed fields in Django?
by Nick Joyce
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Hi Bryan,
Welcome!
I hadn't realised that foreign key relationships were not being
followed on encoding.
I have spent some time putting together an adapter that support django
foreign keys out of the box without you (the user) having to do
anything except provide a `select_related`.
An example:
# models
class Author(models.Model):
name = models.CharField(max_length=100)
class Book(models.Model):
title = models.CharField(max_length=50)
author = models.ForeignKey(Author)
# views
import pyamf
from pyamf.remoting.gateway.django import DjangoGateway
from myproject.myapp.models import Book
def only_books():
return Book.objects.all()
def books_and_authors():
return Book.objects.select_related().all()
gateway = DjangoGateway({
'only_books': only_books,
'books_and_authors': books_and_authors
})
The `only_books` method will return a list of book objects with no
author objects (as foreign keys are lazily loaded) whereas
`books_and_authors` will return books with author objects attached to
them. <-- Hope that all makes sense :)
If you want this behaviour then apply the diff attached to your pyamf
tree. I have (lightly) tested for encoding but not decoding so use
with caution.
If the patch seems reasonable we can get some tests for it and make it
part of 0.4.1.
Joel, this should save you some time investigating the cache issue you
were having - hope it goes some way to solving your problem.
Cheers,
Nick
On 26 Jan 2009, at 22:11, Bryan Hughes wrote:
> I don't mean to second guess, but are you certain DjangoAMF doesn't
> handle ForeignKeys in the manner I described? I read through this
> post (http://sourceforge.jp/forum/forum.php?forum_id=10573&thread_id=16153
> ) and the author implies this functionality has been made available
> in DjangoAMF 0.7.
>
> Thank you again for your help. Just getting frustrated with
> something I was hoping would be straightforward.
>
>
> On Mon, Jan 26, 2009 at 4:44 PM, Joel <imlowdown@...> wrote:
> DjangoAMF doesn't handle it at all, you simply get the title_id:int
> back (as you do with PyAMF). It is also unsupported (for all
> practical purposes) and has some fairly crippling errors. Do not want.
>
> Nick explained to me earlier this month how to override the Cache
> creation class to build your own custom cache. I would bet you could
> do this and attach the object cleanly to the returned object. I
> haven't tried this yet, but it is on my list of things to do. I will
> report back if I have success. Will probably test it out tonight.
>
>
> On Mon, Jan 26, 2009 at 3:35 PM, Bryan Hughes <huuuze@...>
> wrote:
> Thanks for the response. From what I gather, adding the _cache
> fields to my VO seems a little dirty.
>
> Does anyone know if DjangoAMF handles this dilemma in a cleaner
> manner?
>
>
>
> On Mon, Jan 26, 2009 at 4:30 PM, Joel <imlowdown@...> wrote:
> "I personally hate this and wish it was either cleaner or more
> controllable (in an easy way)."
>
> I should add, but not so much that I get off my lazy butt and
> contribute to the project in a meaningful way. Thanks PyAmf dev
> team, you guys are awesome! I would like to turn off the caching
> globally though :>
>
>
> On Mon, Jan 26, 2009 at 3:24 PM, Joel <imlowdown@...> wrote:
> http://pastebin.com/m2ffcb77d
>
> I use these methods to grab related models and whatnot.
>
>
> ReferenceError: Error #1056: Cannot create property _title_cache on
> com.myproject.models.vo.BookVO
>
> If you create a TitleVO object and then make a _title_cache:TitleVO
> property it will do some ORM bits. I personally hate this and wish
> it was either cleaner or more controllable (in an easy way).
>
> -joel
>
>
> On Mon, Jan 26, 2009 at 3:01 PM, Bryan Hughes <huuuze@...>
> wrote:
> I need some help! Please see the question I posted here:
>
> http://stackoverflow.com/questions/481110/how-can-i-use-flex-to-access-foreign-keyed-fields-in-django
>
> Does anyone know of a solution? The one posted in the thread
> results in the following error:
>
> ReferenceError: Error #1056: Cannot create property _title_cache on
> com.myproject.models.vo.BookVO
>
> _______________________________________________
> PyAMF users mailing list - users@...
> http://lists.pyamf.org/mailman/listinfo/users
>
>
>
>
> _______________________________________________
> PyAMF users mailing list - users@...
> http://lists.pyamf.org/mailman/listinfo/users
>
>
>
> _______________________________________________
> PyAMF users mailing list - users@...
> http://lists.pyamf.org/mailman/listinfo/users
>
>
>
> _______________________________________________
> PyAMF users mailing list - users@...
> http://lists.pyamf.org/mailman/listinfo/users
>
>
> _______________________________________________
> PyAMF users mailing list - users@...
> http://lists.pyamf.org/mailman/listinfo/users
_______________________________________________
PyAMF users mailing list - users@...
http://lists.pyamf.org/mailman/listinfo/users
Welcome!
I hadn't realised that foreign key relationships were not being
followed on encoding.
I have spent some time putting together an adapter that support django
foreign keys out of the box without you (the user) having to do
anything except provide a `select_related`.
An example:
# models
class Author(models.Model):
name = models.CharField(max_length=100)
class Book(models.Model):
title = models.CharField(max_length=50)
author = models.ForeignKey(Author)
# views
import pyamf
from pyamf.remoting.gateway.django import DjangoGateway
from myproject.myapp.models import Book
def only_books():
return Book.objects.all()
def books_and_authors():
return Book.objects.select_related().all()
gateway = DjangoGateway({
'only_books': only_books,
'books_and_authors': books_and_authors
})
The `only_books` method will return a list of book objects with no
author objects (as foreign keys are lazily loaded) whereas
`books_and_authors` will return books with author objects attached to
them. <-- Hope that all makes sense :)
If you want this behaviour then apply the diff attached to your pyamf
tree. I have (lightly) tested for encoding but not decoding so use
with caution.
If the patch seems reasonable we can get some tests for it and make it
part of 0.4.1.
Joel, this should save you some time investigating the cache issue you
were having - hope it goes some way to solving your problem.
Cheers,
Nick
On 26 Jan 2009, at 22:11, Bryan Hughes wrote:
> I don't mean to second guess, but are you certain DjangoAMF doesn't
> handle ForeignKeys in the manner I described? I read through this
> post (http://sourceforge.jp/forum/forum.php?forum_id=10573&thread_id=16153
> ) and the author implies this functionality has been made available
> in DjangoAMF 0.7.
>
> Thank you again for your help. Just getting frustrated with
> something I was hoping would be straightforward.
>
>
> On Mon, Jan 26, 2009 at 4:44 PM, Joel <imlowdown@...> wrote:
> DjangoAMF doesn't handle it at all, you simply get the title_id:int
> back (as you do with PyAMF). It is also unsupported (for all
> practical purposes) and has some fairly crippling errors. Do not want.
>
> Nick explained to me earlier this month how to override the Cache
> creation class to build your own custom cache. I would bet you could
> do this and attach the object cleanly to the returned object. I
> haven't tried this yet, but it is on my list of things to do. I will
> report back if I have success. Will probably test it out tonight.
>
>
> On Mon, Jan 26, 2009 at 3:35 PM, Bryan Hughes <huuuze@...>
> wrote:
> Thanks for the response. From what I gather, adding the _cache
> fields to my VO seems a little dirty.
>
> Does anyone know if DjangoAMF handles this dilemma in a cleaner
> manner?
>
>
>
> On Mon, Jan 26, 2009 at 4:30 PM, Joel <imlowdown@...> wrote:
> "I personally hate this and wish it was either cleaner or more
> controllable (in an easy way)."
>
> I should add, but not so much that I get off my lazy butt and
> contribute to the project in a meaningful way. Thanks PyAmf dev
> team, you guys are awesome! I would like to turn off the caching
> globally though :>
>
>
> On Mon, Jan 26, 2009 at 3:24 PM, Joel <imlowdown@...> wrote:
> http://pastebin.com/m2ffcb77d
>
> I use these methods to grab related models and whatnot.
>
>
> ReferenceError: Error #1056: Cannot create property _title_cache on
> com.myproject.models.vo.BookVO
>
> If you create a TitleVO object and then make a _title_cache:TitleVO
> property it will do some ORM bits. I personally hate this and wish
> it was either cleaner or more controllable (in an easy way).
>
> -joel
>
>
> On Mon, Jan 26, 2009 at 3:01 PM, Bryan Hughes <huuuze@...>
> wrote:
> I need some help! Please see the question I posted here:
>
> http://stackoverflow.com/questions/481110/how-can-i-use-flex-to-access-foreign-keyed-fields-in-django
>
> Does anyone know of a solution? The one posted in the thread
> results in the following error:
>
> ReferenceError: Error #1056: Cannot create property _title_cache on
> com.myproject.models.vo.BookVO
>
> _______________________________________________
> PyAMF users mailing list - users@...
> http://lists.pyamf.org/mailman/listinfo/users
>
>
>
>
> _______________________________________________
> PyAMF users mailing list - users@...
> http://lists.pyamf.org/mailman/listinfo/users
>
>
>
> _______________________________________________
> PyAMF users mailing list - users@...
> http://lists.pyamf.org/mailman/listinfo/users
>
>
>
> _______________________________________________
> PyAMF users mailing list - users@...
> http://lists.pyamf.org/mailman/listinfo/users
>
>
> _______________________________________________
> PyAMF users mailing list - users@...
> http://lists.pyamf.org/mailman/listinfo/users
_______________________________________________
PyAMF users mailing list - users@...
http://lists.pyamf.org/mailman/listinfo/users
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