This is a wrapper for yamerl - a native Erlang YAML parser which brings all of the functionalities to Elixir language.

Add Yaml Elixir as a dependency in your mix.exs file.

defp deps do
  [
     # ...
    {:yaml_elixir, "~> x.x.x"}, # where "x.x.x" equals version in mix.exs
  ]
end

ALWAYS MAKE SURE YOU USE THE LATEST VERSION FROM mix.ex

You should also update your applications list to include Yaml Elixir:

def application do
  [
     applications: [
       # ...
       :yaml_elixir,
     ]
  ]
end

Once you've done that, run mix deps.get in your command line to fetch the dependency.

With Yaml Elixir you have an access to two methods, one for parsing a string and an another one for parsing a file.

Run iex -S mix in your terminal to try how their works.

iex(1)>     yaml = """
...(1)>       a: a
...(1)>       b: 1
...(1)>       c: true
...(1)>       d: ~
...(1)>       e: nil
...(1)>     """
"  a: a\n  b: 1\n  c: true\n  d: ~\n  e: nil\n"
iex(2)> YamlElixir.read_from_string yaml
%{"a" => "a", "b" => 1, "c" => true, "d" => nil, "e" => "nil"}

iex(1)> path = File.cwd! |> Path.join("test/fixtures/flat.yml")
"/Users/squixy/Desktop/yaml-elixir/test/fixtures/flat.yml"
iex(2)> YamlElixir.read_from_file path
%{"a" => "a", "b" => 1, "c" => true, "d" => nil, "e" => []}

By default, all map keys are processed as strings, as are all bareword or quoted values. If you would prefer to autodetect keys and values that begin with : as atoms, this can be accomplished by passing atoms: true as an option to any of the read_* functions.

iex(1)>     yaml = """
...(1)>       a: a
...(1)>       b: 1
...(1)>       c: true
...(1)>       d: ~
...(1)>       e: nil,
...(1)>       :f: :atom
...(1)>     """
"  a: a\n  b: 1\n  c: true\n  d: ~\n  e: nil\n"
iex(2)> YamlElixir.read_from_string yaml, atoms: true
%{:f => :atom, "a" => "a", "b" => 1, "c" => true, "d" => nil, "e" => "nil"}

Atoms are not garbage collected by BEAM, so be careful with this option, and don't use it with user-supplied input. One other caveat: if you enable autodetection of atoms, any string values entered (e.g., ":not_really_an_atom") will be converted to atoms, as well. If you only need to support a few atom values, you might be better off enabling yamerl's custom tag for atoms:

:yamerl_app.set_param(:node_mods, [:yamerl_node_erlang_atom])

and then using the somewhat inconvenient syntax for it:

atom_key: !<tag:yamerl,2012:atom> atom_value

The YamlElixir.Sigil module provides the ~y sigil that can be useful for example for keeping short configurations or other inlined yaml.

import YamlElixir.Sigil

@config ~y"""
debug: false
port:  9200
files:
  - some/file.csv
  - another/file.csv
"""

Use the a sigil modifier to turn on atom values from yaml:

~y":answer: yes"a

You can find more examples in test directory.

Sometimes, you may want to use yaml_elixir in your mix tasks. To do that, you must ensure that the application has started.

Application.ensure_all_started(:yaml_elixir)

After that, you will be able to use yaml-elixir in your mix tasks.

Credits to bobbypriambodo.

In case of any problems or suggestions do not hesitate and create a pull request.