Cookbooks
Elixir
Chapter 10. Data Formats and Serialization
Working with YAML

Elixir:
Working with YAML

How to:

Elixir doesn’t include built-in YAML support. However, you can use third-party libraries such as yamerl or yaml_elixir to work with YAML. Here, we’ll focus on yaml_elixir for its ease of use and comprehensive features.

First, add yaml_elixir to your mix.exs dependencies:

defp deps do
  [
    {:yaml_elixir, "~> 2.9"}
  ]
end

Then, run mix deps.get to fetch the new dependency.

Reading YAML

Given a simple YAML file, config.yaml, which looks like this:

database:
  adapter: postgres
  username: user
  password: pass

You can read this YAML file and convert it to an Elixir map like so:

defmodule Config do
  def read do
    {:ok, content} = YamlElixir.read_from_file("config.yaml")
    content
  end
end

# Sample usage
Config.read()
# Output: 
# %{
#   "database" => %{
#     "adapter" => "postgres",
#     "username" => "user",
#     "password" => "pass"
#   }
# }

Writing YAML

To write a map back to a YAML file:

defmodule ConfigWriter do
  def write do
    content = %{
      database: %{
        adapter: "mysql",
        username: "root",
        password: "s3cret"
      }
    }
    
    YamlElixir.write_to_file("new_config.yaml", content)
  end
end

# Sample usage
ConfigWriter.write()
# This will create or overwrite `new_config.yaml` with the specified content

Notice how yaml_elixir allows for a straightforward translation between YAML files and Elixir data structures, making it an excellent choice for Elixir programmers needing to work with YAML data.

Working with XML