Document setIn() should work if document contents are empty

[akprgm]

my yaml file may or may not have keys and values, if doesn't have keys then i want create it. I think this issue documented as well but is there any way to achieve this.
conf.yml

external_servivces:
   service_1: 
      property_1: 1

const fs = require('fs');
const yaml = require('yaml');
const file = fs.readFileSync('./conf.yaml', 'utf8')
const doc =yaml.parseDocument(file);
doc.setIn(['external_servivces', 'service_1', 'property_1'], 1);

[eemeli]

I'm not sure that I understand the question here. The example above should just work. Perhaps if you could give an example which fails to work as intended?

[akprgm]

Above example doesn't work, if the those properties doesn't exist in yaml file.

Error: Expected YAML collection at external_services. Remaining path: service_1

In my case yaml is updated by multiple teams, if there is already a key for external_service then i want to add other sub properties, else i want to create it and then add it.

Also i tried doing this, but getting the same error

if (!doc.has('external_services')) {
    doc.setIn(['external_services'], "");
    doc.setIn(['external_services','service_1'], '')
    doc.setIn(['external_services','service_1', 'property_1'], 'testing')
}

[eemeli]

Ah, I think I see now. When you're parsing empty input, it's not possible to determine what shape those contents are expected to have. A YAML document is not limited to having a key-value mapping at its root.

So what you should probably do is that once you've parsed the config file into a YAML document, check that it's a map, and if it's not, assign a map to the contents. After that, the setIn() will work as you expect:

import YAML from 'yaml'
import { YAMLMap } from 'yaml/types'

const doc = YAML.parseDocument(src)
if (doc.contents instanceof YAMLMap) {
  // no need to do anything
} else if (doc.contents) {
  // the contents have been parsed as something other than a mapping
  // this is probably an error
} else {
  doc.contents = YAML.createNode({})
}

doc.setIn(...)

For the particular case where contents are empty, it would make sense for the root mapping to be auto-generated because there's no pre-existing value to override. Especially as that's what setIn() already does within collections.

[akprgm]

Also it's not necessary that this YAML file will be empty and not sure how above snippet solve my problem.

eg. Existing YAML Doc

other_things: abc
external_servivces: #may exist
   service_1:  #may exist
      property_1: 1 #may exist

So my end goal here is to update the value of property_1 but to set this property i will have to check if parents properties are there. This can be easily achieved using Parse and Stringify but i also want to preserve comments and line breaks here.

[eemeli]

This should now be fixed. There were in fact two separate bugs here:

1. When parsing collections the schema wasn't being properly passed to its constructor, so the intermediate collection creation didn't work like it should have.
2. The empty-document case now gets special handling to allow for set() and setIn() to work.