auxmoney / uyaml

Unstructured YAML helper for Go

uyaml

Package uyaml provides utilities for working with unstructured yaml documents. It allows structures to be queried, modified, and removed using a small query language that somewhat resembles CSS selectors (in some parallel dimension).

This package is considered of beta quality, and may behave oddly in some edge cases. In case this happens, please file an issue to the corresponding repository.

Querying Values

Let's suppose you have a extensive YAML document with a key nested under some complicated hierarchy. One option is to implement structures matching the document's, so yaml.Unmarshal can do its job. The other option is to unmarshal into a map of interfaces, or slice of interfaces. uyaml implements two methods to handle this scenario: DigItem and MustDigItem. For example, consider the following YAML document:

userCount: 2
users:
- name: josie
  roles:
  - bot
  - foo
  - bar
- name: lester
  roles:
  - dummy

In order to obtain roles for a user under the key josie, DigItem can be used:

doc, err := uyaml.Decode(...)
if err != nil {
    ...
}
ok, item, err := doc.DigItem("users.(name='josie').roles")
if err != nil {
	...
}
if !ok {
	...
}

str, ok := item.String()
if ok {
    fmt.Printf("%#v", item.)
}

MustDigItem works just like DigItem, except it only have a single return value, and panics in case the item cannot be found or the provided path cannot be parsed.

Removing Values

Removing values can be done with the Remove method, which takes a single path to be removed. In case the path does not exist, a noop happens and the same object is returned.

doc, err := uyaml.Decode(...)
if err != nil {
...
}
doc, err := doc.Remove("users.(name='josie')")

Setting Values

Set can be used to inject arbitrary values into the document's structure. For instance (errors checking omitted for brevity):

	val, err := data.Set("users.(name='dummy').test", true)
	yam, err := val.Encode()
	fmt.Println(yam)

Would print the following structure:

   userCount: 2
   users:
   - name: josie
     roles:
     - bot
     - foo
     - bar
   - name: lester
     roles:
     - dummy
   - name: dummy
     test: true

License

MIT License

Copyright (c) 2021 Victor Gama de Oliveira

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.