ListField should enforce that input is a list

[pattisdr]

Purpose

A dictionary is allowed as input in a ListField. If a dictionary is received as input, the keys of the object are retained, and the values are ignored. I assume the ListField should enforce that the input is an array, especially because the error message in to_internal_value includes "not a list" if something is wrong with the data.

Changes

Enforces that data cannot be a collections.Mapping.

[pattisdr]

I could include tuples and sets

if not isinstance(data, (list, tuple, Set)):
    self.fail('not_a_list', input_type=type(data).__name__)

[xordoquy]

Thanks for the path.
I don't think it should force to list / tuple / set. Any iterable should do.
The key issue here is that a dictionary is an iterable on the keys.
Questions to be answered:

• do we really want to limit the valid type to a limited set ?
• can't we just exclude dictionaries from the ListField ?

[pattisdr]

You're right, I think excluding dictionaries from the ListField in addition to what was already in that line would do the trick.

[tomchristie]

Agree - excluding dicts sounds like a good way around to do this.

[xordoquy]

Note: by dict we should read any mapping type.

[tomchristie]

Note: by dict we should read any mapping type.

IDK - any chance that could be a bit fuzzy in cases we've not thought of?
No strong opinion tho'

[xordoquy]

Well, collections.Mapping should be a good base class to test against (as opposed to just dict).

[foresmac]

Probably want tests that prove this works as intended.

[xordoquy]

Yup, having tests would be great so we merge it.

[pattisdr]

Tests added.

[tomchristie]

Looks good, thanks!