How to read the yaml file as dictionary and update value using python

Question

I need to write function to read the YAML file and update the specific value. The YAML file is dictionary,

sample :
    test_example:
    parent:
      attribute_1: 2
      attribute_2: 2
    parent2:
      childList:
        - group: 2
          type: "test"
          track_int:
            - key_1: 3
              key_2: 25
              state: present
          state: present
        - group: 4
          typr: "old"
          track_int:
            - key_1: 3
              key_2: 25
              state: present
          state: present

Now I need to write function to pass the key and it should replace the value for specific value ex - update the test_example["parent2"]["childList"][0]["group"] to 4 and update test_example["parent"]["attribute_2"] to 5

How can I do that?

Answer 1

If you want to preserve the rest of the input file as-is, including the superfluous quotes around "test" and "old" and the offset of the dash in your sequence indent then your only real option is to use ruamel.yaml (disclaimer: I am the author of that package):

import sys
import ruamel.yaml

yaml = ruamel.yaml.YAML()
yaml.preserve_quotes = True
yaml.indent(mapping=4, sequence=4, offset=2)

with open('input.yaml') as fp:
    data = yaml.load(fp)

test_example = data['sample']
test_example["parent2"]["childList"][0]["group"] =4
test_example["parent"]["attribute_2"] = 5
yaml.dump(data, sys.stdout)

gives:

sample:
    test_example:
    parent:
        attribute_1: 2
        attribute_2: 5
    parent2:
        childList:
          - group: 4
            type: "test"
            track_int:
              - key_1: 3
                key_2: 25
                state: present
            state: present
          - group: 4
            typr: "old"
            track_int:
              - key_1: 3
                key_2: 25
                state: present
            state: present

The naming of your Python test_example of course cannot correspond to the test_example of your input file. That gets loaded as None (assuming your input is really indented as you presented your YAML document).