Problem:
You are trying to yaml.safe_dump()
an object which is (or contains) a defaultdict, e.g.:
import yaml import collections yaml.safe_dump(collections.defaultdict(list))
which results in the following exception:
Traceback (most recent call last): File "<stdin>", line 1, in <module> File "/home/uli/.local/lib/python3.10/site-packages/yaml/__init__.py", line 269, in safe_dump return dump_all([data], stream, Dumper=SafeDumper, **kwds) File "/home/uli/.local/lib/python3.10/site-packages/yaml/__init__.py", line 241, in dump_all dumper.represent(data) File "/home/uli/.local/lib/python3.10/site-packages/yaml/representer.py", line 27, in represent node = self.represent_data(data) File "/home/uli/.local/lib/python3.10/site-packages/yaml/representer.py", line 58, in represent_data node = self.yaml_representers[None](self, data) File "/home/uli/.local/lib/python3.10/site-packages/yaml/representer.py", line 231, in represent_undefined raise RepresenterError("cannot represent an object", data) yaml.representer.RepresenterError: ('cannot represent an object', defaultdict(<class 'list'>, {}))
Solution:
You need to add a custom representer to implicitly convert the defaultdict
to a dict.
Before running yaml.safe_dump()
, add the following lines:
import collections from yaml.representer import Representer yaml.SafeDumper.add_representer(collections.defaultdict, Representer.represent_dict)
Now, the yaml.safe_dump()
call should work perfectly:
yaml.safe_dump(collections.defaultdict(list)) # Returns'{}\n'