Yags is a simple YAML getter/setter written in GO.

Current features are:

• get any value from any valid yaml file
• set a value for a key in yaml file

• Installation
• Usage
  • Get
  • Set
• Upcoming

To install yags run the following command.

$ go get github.com/farbanas/yags

Try running it in your terminal.

$ yags
Error: subcommand has to be `get` or `set`.
Usage: yags (get|set)

In case you get something like

$ yags
yags: command not found

please check that your $GOPATH/bin is included in your PATH. You can set it for the current shell by running:

$ export PATH:${GOPATH:-~/go}/bin

To save that configuration, put it in your ~/.bashrc or ~/.zshrc.

Yags has two subcommands that it supports, get and set.

$ yags
Error: subcommand has to be `get` or `set`.
Usage: yags (get|set)

The get subcommand is used for getting a value from yaml file.

$ yags get 
Error: filePath cannot be empty!
Error: query cannot be empty!

Usage of yags get:
  -filePath string
        Path to yaml file.
  -query string 
        Query for the value to get. Query should be in the dot format, for example if you want to set the value of a yaml map entry that is on the third level,
        your query would look something like 'first.second.third'. It also supports array indexes (indexes are 0-indexed). In the case that you have an array,
        your query would look something like 'first.second.2.third'.

As you can see from the command usage, it requires two parameters, path to the yaml file from which you want to get the value and a query that specifies which value you want. The first parameter is straightforward, but I will explain query a bit more.

Query is a dot separated collection of keys that are parents to the value you want to get. For example, you have a yaml like this (this is a randomly generated yaml btw):

potatoes:
- percent: true
  soil:
    engineer: programmer
    through:
    - rabbit
    - grass
    - station
    tip: mind
  stiff: tight
- false
- true
satellites: record
worry: deer

If you wanted to get the value of engineer, your query would look like potatoes.0.soil.engineer. The only thing that should be clarified in this string is the 0. It represents the index of the yaml array. We are taking the first element (0-indexed). At that point, you could imagine that you now have a yaml like this:

percent: true
soil:
  engineer: programmer
  through:
  - rabbit
  - grass
  - station
  tip: mind
stiff: tight

which is why we need soil next and engineer after that. If you saved that yaml into a file named example.yaml and ran yags on it, you would get something like this:

$ yags get -filePath example.yaml -query potatoes.0.soil.engineer
programmer

Different example, where we want to get grass:

$ yags get -filePath example.yaml -query potatoes.0.soil.through.1
grass

The set subcommand is similar to the get subcommand, it just needs one parameter, the value that you want to set.

$ yags set
Error: filePath cannot be empty!
Error: key cannot be empty!
Error: value cannot be empty!

Usage of yags get:
  -filePath string
        Path to yaml file.
  -query string 
        Query for the value to set. Query should be in the dot format, for example if you want to set the value of a yaml map entry that is on the third level,
        your query would look something like 'first.second.third'. It also supports array indexes (indexes are 0-indexed). In the case that you have an array,
        your query would look something like 'first.second.2.third'.
  -value string
        Value that you want to set.

Querying works the same as for the get subcommand.

Let's take the same yaml file as for the get subcommand.

potatoes:
- percent: true
  soil:
    engineer: programmer
    through:
    - rabbit
    - grass
    - station
    tip: mind
  stiff: tight
- false
- true
satellites: record
worry: deer

Let's say we want to change the value mind which is associated to key tip to please. It would look like this:

$ yags set -filePath example.yaml -query potatoes.0.soil.tip -value please
$ echo "$?"
0

In this case yags doesn't output anything, but it finished successfully which can be seen if you inspect the exit code. You will now have a yaml file looking like this:

potatoes:
- percent: true
  soil:
    engineer: programmer
    through:
    - rabbit
    - grass
    - station
    tip: please
  stiff: tight
- false
- true
satellites: record
worry: deer

• When setting, create a key if it does not exist (should be switchable with command line option)
• Set complex values instead of only strings
• Better logging