python yaml update preserving order and comments

Question

Im inserting a key into Yaml using python but I would like to preserve order and comments in the yaml

#This Key is used for identifying Parent tests
    ParentTest:
       test:
         JOb1: myjob
         name: testjob
         arrive: yes

Now Im using below code to insert new key

params['ParentTest']['test']['new_key']='new value'
yaml_output=yaml.dump(pipeline_params, default_flow_style=False)

How to preserve the exact order and comments ?

Below arrive moved up but I want to preserve order & comments as well

output is :

 ParentTest:
       test:
         arrive: yes
         JOb1: myjob
         name: testjob

Answer 1

pyyaml cannot keep comments, but ruamel does.

Try this:

doc = ruamel.yaml.load(yaml, Loader=ruamel.yaml.RoundTripLoader)
doc['ParentTest']['test']['new_key'] = 'new value'
print ruamel.yaml.dump(doc, Dumper=ruamel.yaml.RoundTripDumper)

The order of keys will also be preserved.

Edit: Look at Anthon's answer from 2020: https://stackoverflow.com/a/59659659/93745