PyYAML : Control ordering of items called by yaml.load()

Question

I have a yaml setting file which creates some records in db:

setting1:
  name: [item,item]
  name1: text
anothersetting2:
  name: [item,item]
  sub_setting:
      name :[item,item]

when i update this file with setting3 and regenerate records in db by:

import yaml
fh = open('setting.txt', 'r')
setting_list = yaml.load(fh)
for i in setting_list:
    add_to_db[i]

it's vital that the order of them settings (id numbers in db) stay the same each time as im addig them to the db... and setting3 just gets appended to the yaml.load()'s end so that its id doesn't confuse any records which are already in the db ... At the moment each time i add another setting and call yaml.load() records get loaded in different order which results in different ids. I would welcome any ideas ;)

EDIT: I've followed abarnert tips and took this gist https://gist.github.com/844388

Works as expected thanks !

Answer 1

My project oyaml is a drop-in replacement for PyYAML, which will load maps into collections.OrderedDict instead of regular dicts. Just pip install it and use as normal - works on both Python 3 and Python 2.

Demo with your example:

>>> import oyaml as yaml  # pip install oyaml
>>> yaml.load('''setting1:
...   name: [item,item]
...   name1: text
... anothersetting2:
...   name: [item,item]
...   sub_setting:
...       name :[item,item]''')
OrderedDict([('setting1',
              OrderedDict([('name', ['item', 'item']), ('name1', 'text')])),
             ('anothersetting2',
              OrderedDict([('name', ['item', 'item']),
                           ('sub_setting', 'name :[item,item]')]))])

Note that if the stdlib dict is order preserving (Python >= 3.7, CPython >= 3.6) then oyaml will use an ordinary dict.

Answer 2

You can now use ruaml.yaml for this.

From https://pypi.python.org/pypi/ruamel.yaml:

ruamel.yaml is a YAML parser/emitter that supports roundtrip preservation of comments, seq/map flow style, and map key order