generate_thumbnail() doesn't work right when using Multiple Image Sets

[rogeriobastos]

When using Multiple Image Sets generate_thumbnail() only create a thumbnail to the first image.
This is happening because generate_thumbnail() thinks a thumbnail was already generated and return the thumbnail of the first image.

I'm using Python (2.7.13), SQLAlchemy (1.1.14) and SQLAlchemy-ImageAttach (1.1.0).

[and-semakin]

I can confirm the issue on Python 3.6.4, SQLAlchemy 2.3.2 and sqlalchemy-imageattach 1.1.0. I think it happens because generate_thumbnail() does not consider our 'extra discriminating primary key columns' and just search for matches though all the thumbnails.

That's what I see via debugger (entity.py, line 759):

SELECT level_scheme.width AS level_scheme_width, level_scheme.height AS level_scheme_height, level_scheme.mimetype AS level_scheme_mimetype, level_scheme.original AS level_scheme_original, level_scheme.created_at AS level_scheme_created_at, level_scheme.level_id AS level_scheme_level_id, level_scheme.order_index AS level_scheme_order_index 
FROM level_scheme 
WHERE %(param_1)s = level_scheme.level_id AND level_scheme.width = %(width_1)s

That's just about what I expected to see, because I have additional column order_index in the primary key:

SELECT level_scheme.width AS level_scheme_width, level_scheme.height AS level_scheme_height, level_scheme.mimetype AS level_scheme_mimetype, level_scheme.original AS level_scheme_original, level_scheme.created_at AS level_scheme_created_at, level_scheme.level_id AS level_scheme_level_id, level_scheme.order_index AS level_scheme_order_index 
FROM level_scheme 
WHERE %(param_1)s = level_scheme.level_id AND level_scheme.width = %(width_1)s AND level_scheme.order_index = %(order_index_1)s

[and-semakin]

It seems to me that author forget to apply filter_by(**self.identity_map) in the ImageSubset.__init__() constructor. As I can see filter_by() function is applied later in ImageSubset.count(). I think that is the trick. Will check it out.

Edit.
Hmm, no, it was not so easy.

[and-semakin]

@dahlia, your code is beautiful and well-documented but it's very difficult to unravel crazy genealogy of classes and mixins 😨 uselist=True mode seems to be very buggy: at least I get different exceptions if I add list of images to existing object or not.