Re: Idea for ManyTomManyField extention

[Ian Holsman]

Hi Neilen. I think this would be a good idea, as I frequently have a M2M type relationship with one or two fields on that field. but personally I just use foreign keys on the middle table, as I think it makes the code more readable, and allows you to be more flexible with it. (for example a M2M with a generic flavor) What I would like to see (and might already be there.. I haven't looked to closely lately) is a common naming standard for the relationships (foreign, one-to-one,  or many) so that I can just switch a M2M to a Foreign key in the model with no effect on the code which uses it. (django might do this.. it's been a while since I used M2M) regards Ian On 29/07/2006, at 8:50 AM, Neilen Marais wrote: Hi I'm just testing the waters to see what people think about an extended ManyToManyField type that allows the addition of extra info to a link withouth having to use an intermediary table/model like here: http://www.djangoproject.com/documentation/models/m2m_intermediary/ . Using the intermediary table is not horrible, but my objections are:  - It adds an unnecesary level of indirection when all that is desired is to add some info to a relation.  - If extra info is to be added to an existing app it may require quite a few of code changes and also extra work to do data migration. Let me describe how I'd like it to work. The model definition should look something like this: from django.db import models class Tag(models.Model):     name = models.CharField(maxlength=255) class ImageTagInfo(models.Model):     # Something so that a seperate table is not created. Perhaps using     # a different base class from models.Model could be done instead?     extra_tag_info = models.SomeFieldType() class Image(models.Model):     # various image info fields...     tags = model.ManyToManyField(Tag, link_info=ImageTagInfo) In use it should work exactly like a normal m2m relation, except that the additional fields described in ImageTagInfo should be added to the resulting Tag objects when accessed through the Image.tags m2m manager, while the same fields should be added to Image objects accessed through the Tag.image_set m2m manager.  Perhaps some checks or name mangling of the ImageTagInfo fieldnames could be done to prevent field name conflicts between the models. It may also be a good idea to have the Tag objects accessed through the Image m2m manager be subclasses of both Tag and ImageTagInfo, and similarly the images should be subclasses of both ImageTagInfo and Image when accessed through the Tag.image_set m2m manager. This idea could be implemented on the DB side by adding the ImageTagInfo fields to the m2m link table. Does this sound like a good idea? Bad idea? If someone is willing to do the work, would the patches be accepted? Regards Neilen --  you know its kind of tragic  we live in the new world but we've lost the magic -- Battery 9 (www.battery9.co.za) --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Django developers" group. To post to this group, send email to django-developers@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/django-developers -~----------~----~----~----~------~----~------~--~---