Can PyYAML dump dict items in non-alphabetical order?

Question

I\'m using yaml.dump to output a dict. It prints out each item in alphabetical order based on the key.

>>> d = {\"z\":0,\"y\":0,\"x\":         


        

Answer 1

One-liner to rule them all:

yaml.add_representer(dict, lambda self, data: yaml.representer.SafeRepresenter.represent_dict(self, data.items()))

That's it. Finally. After all those years and hours, the mighty represent_dict has been defeated by giving it the dict.items() instead of just dict

Here is how it works:

This is the relevant PyYaml source code:

    if hasattr(mapping, 'items'):
        mapping = list(mapping.items())
        try:
            mapping = sorted(mapping)
        except TypeError:
            pass
    for item_key, item_value in mapping:

To prevent the sorting we just need some Iterable[Pair] object that does not have .items().

dict_items is a perfect candidate for this.

Here is how to do this without affecting the global state of the yaml module:

#Using a custom Dumper class to prevent changing the global state
class CustomDumper(yaml.Dumper):
    #Super neat hack to preserve the mapping key order. See https://stackoverflow.com/a/52621703/1497385
    def represent_dict_preserve_order(self, data):
        return self.represent_dict(data.items())    

CustomDumper.add_representer(dict, CustomDumper.represent_dict_preserve_order)

return yaml.dump(component_dict, Dumper=CustomDumper)