Proper handling mapping.DictField default values

[GoogleCodeExporter]

`DictField` accepts default value and has default default as empty dict. But if 
`mapping` parameter is specified user is expecting empty `Mapping` instance as 
default value not empty dict. Or if default is already `Mapping` instance so it 
doesn't have `copy()` method and that causes an error.

Patch is attached.

Original issue reported on code.google.com by daevaorn on 6 Jun 2011 at 11:31

Attachments:

• dictfield_default.diff

[GoogleCodeExporter]

I understand idea of this patch, but it doesn't solves issue:
class Image(Mapping):
    name = TextField()
    url = TextField()

class Post(Mapping):
    title = TextField()
    logo = DictField(Image, default={'name': 'post logo'})
    attached_image = DictField(Mapping.build(
        name=TextField(), 
        url=TextField()
    ), default=Image(name='attached image'))

post = Post(title='test post') # TypeError: MappingMeta object argument after 
** must be a mapping, not Image

I suppose that better to implement full dict API to Mapping instance because it 
represented ORM to dict object instead of trying to do same thing within Field 
instances.

Original comment by kxepal on 8 Jun 2011 at 4:28

[GoogleCodeExporter]

This issue has been migrated to GitHub. Please continue discussion here:

https://github.com/djc/couchdb-python/issues/185

Original comment by djc.ochtman on 15 Jul 2014 at 7:21