I’ve got an object with a short string attribute, and a long multi-line string attribute. I want to write the short string as a YAML quoted scalar, and the multi-line string as a literal scalar:
my_obj.short = "Hello" my_obj.long = "Line1nLine2nLine3"
I’d like the YAML to look like this:
short: "Hello" long: | Line1 Line2 Line3
How can I instruct PyYAML to do this? If I call yaml.dump(my_obj)
, it produces a dict-like output:
{long: 'line1 line2 line3 ', short: Hello}
(Not sure why long is double-spaced like that…)
Can I dictate to PyYAML how to treat my attributes? I’d like to affect both the order and style.
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Answer
import yaml from collections import OrderedDict class quoted(str): pass def quoted_presenter(dumper, data): return dumper.represent_scalar('tag:yaml.org,2002:str', data, style='"') yaml.add_representer(quoted, quoted_presenter) class literal(str): pass def literal_presenter(dumper, data): return dumper.represent_scalar('tag:yaml.org,2002:str', data, style='|') yaml.add_representer(literal, literal_presenter) def ordered_dict_presenter(dumper, data): return dumper.represent_dict(data.items()) yaml.add_representer(OrderedDict, ordered_dict_presenter) d = OrderedDict(short=quoted("Hello"), long=literal("Line1nLine2nLine3n")) print(yaml.dump(d))
Output
short: "Hello" long: | Line1 Line2 Line3