dumps() crashes with TypeError when a list contains non-string values (e.g. integers)

[anthonyoteri]

Bug

dumps() raises TypeError: argument of type 'int' is not a container or iterable when serializing a list that contains non-string scalar values such as integers or floats.

Root cause

In _dump, when iterating list items, non-dict items are passed directly to _escape():

yield '%s%s\n' % (' ' * (indent + 2), _escape(subvalue))

_escape() does for ch in _ESCAPE_CHARACTERS: if ch in k — which fails when k is an int (or any non-string type) because in on a string requires the left operand to also be a string.

Reproducer

import structprop
structprop.dumps({"ids": [1, 2, 3]})
# TypeError: argument of type 'int' is not a container or iterable

Fix

_escape should coerce its argument to str before testing membership, or _dump should coerce non-string list items to strings before passing them to _escape:

def _escape(k):
    k = str(k)
    for ch in _ESCAPE_CHARACTERS:
        if ch in k:
            return '"%s"' % (k,)
    return k