AttributeError: 'Function' object has no attribute 'items'

[DeoLeung]

from geoalchemy2 import WKBElement
import simplejson as json
json.dumps({'a': [WKBElement('abcde')]})

I tried to use the default as parser to due with WKBElement, but the code is not going into the parser, how could I do the customized serialization?

[etrepum]

I'm not familiar with that library. What is the output of print(repr(WKBElement.__bases__))? What versions of simplejson, geoalchemy2, sqlalchemy, and python are you using?

[DeoLeung]

(<class 'geoalchemy2.elements._SpatialElement'>, <class 'sqlalchemy.sql.functions.Function'>)
simplejson                3.16.0
GeoAlchemy2               0.5.0
python 3.7.2
SQLAlchemy                1.2.18

Thank you~

[etrepum]

I'm afraid that this is awkward with recent versions of simplejson because of the way that sqlalchemy.sql.functions.Function implements __getattr__. The issue is that for any unknown attribute, Function.attribute returns a callable, which for certain properties (such as _asdict and for_json in this case), simplejson thinks the result of that function should be a dict-like or json serializable object but it isn't.

The workaround in this case is to turn off the namedtuple_as_object and for_json options.

json.dumps({'a': [WKBElement('abcde')]}, namedtuple_as_object=False, for_json=False)

This will ensure that these instances will get passed to default.