Get Comment During Iteration In Ruamel.yaml

How can I get the comments when I iterate through the YAML object yaml = YAML() with open(path, 'r') as f: yaml_data = yaml.load(f) for obj in yaml_data: # how to get the

Solution 1:

You did not specify your input, but since your code expects an obj and not a key, I assume the root level of your YAML is a sequence and not mapping. If you want to get the comments after each element (i.e nr 1 and the last) you can do:

import ruamel.yaml

yaml_str = """\
- one  # nr 1
- two 
- three # the last
"""

yaml = ruamel.yaml.YAML()

data = yaml.load(yaml_str)

for idx, obj inenumerate(data):
    comment_token = data.ca.items.get(idx)
    if comment_token isNone:
        continueprint(repr(comment_token[0].value))

which gives:

'# nr 1\n''# the last\n'

You might want to strip of the leading octothorpe and trailing newline.

Please note that this works with the current version (0.15.61), but there is no guarantee it might not to change.

Solution 2:

Using the example from Anthon as well as an issue in ruamel.yaml on sourceforge, here's a set of methods which should allow you to retrieve (almost - see below) all the comments in your documents:

from ruamel.yaml import YAML
from ruamel.yaml.comments import CommentedMap, CommentedSeq

# set attributesdefget_comments_map(self, key):
    coms = []
    comments = self.ca.items.get(key)
    if comments isNone:
        return coms
    for token in comments:
        if token isNone:
            continueelifisinstance(token, list):
            coms.extend(token)
        else:
            coms.append(token)
    return coms

defget_comments_seq(self, idx):
    coms = []
    comments = self.ca.items.get(idx)
    if comments isNone:
        return coms
    for token in comments:
        if token isNone:
            continueelifisinstance(token, list):
            coms.extend(token)
        else:
            coms.append(token)
    return coms

setattr(CommentedMap, 'get_comments', get_comments_map)
setattr(CommentedSeq, 'get_comments', get_comments_seq)

# load string
yaml_str = """\
- name: gather all complex custom facts using the custom module
  hosts: switches
  gather_facts: False
  connection: local
  tasks:
    # There is a bug in ansible 2.4.1 which prevents it loading
    # playbook/group_vars
    - name: ensure we're running a known working version
      assert:
        that:
          - 'ansible_version.major == 2'
          - 'ansible_version.minor == 4'
"""
yml = YAML(typ='rt')
data = yml.load(yaml_str)

defwalk_data(data):
    ifisinstance(data, CommentedMap):
        for k, v in data.items():
            print(k, [ comment.value for comment in data.get_comments(k)])
            ifisinstance(v, CommentedMap) orisinstance(v, CommentedSeq):
                walk_data(v)
    elifisinstance(data, CommentedSeq):
        for idx, item inenumerate(data):
            print(idx, [ comment.value for comment in data.get_comments(idx)])
            ifisinstance(item, CommentedMap) orisinstance(item, CommentedSeq):
                walk_data(item)

walk_data(data)

Here's the output:

0[]
name []
hosts []
gather_facts []
connection []
tasks ['# There is a bug in ansible 2.4.1 which prevents it loading\n', '# playbook/group_vars\n']0[]
name []
assert []
that []0[]1[]

Unfortunately, there are two is one problems that I have encountered which are not covered by this method:

1. You will notice that there is no leading \n in the comments for tasks. As a result, it is not possible with this method to differentiate between comments which start on the same line as tasks or on the next line. Since the CommentToken.start_mark.line only contains the absolute line of the comment, it might be able to be compared to the line of tasks. But, I have not yet found a way to retrieve the line associated with tasks inside the loaded data.
2. There does not seem to be a way that I have found yet to retrieve comments at the head of the document. So, any initial comments would need to be discovered using a method other than to retrieve them outside the yaml reader. But, related to problem #1, these head comments are included in the absolute line count of other comments. To add the comments at the head of the document, you need to use [comment.value for comment in data.ca.comment[1] as per this explanation by Anthon.