matiso

matiso

Convert Elixir maps or structs to YAML

I am building an API that needs to allow the user to download a yaml config file for an external application.
I’m not sure if I’m blind, or there is no Elixir library that converts a map (or struct) into YAML? All I can find is how to decode YAML and parse it into an Elixir data structure, but not the other way around.

Most Liked

michalmuskala

michalmuskala

Valid JSON is valid YAML. Any conforming YAML parser should be able to parse JSON. So if you don’t have any specific needs for the YAML format, doing something like:

"---\n" <> Poison.encode!(data)

will produce something any YAML parser will be able to process.

yoran

yoran

@50kudos For what it’s worth, I found myself in a similar situation. I could parse YAML with yaml-elixir but didn’t have a way to write. So I wrote a short YAML writer myself.

def to_yaml(yaml_map, indentation \\ "") do
    yaml_map
    |> Map.keys
    |> Enum.map(
      fn key ->
        value = Map.fetch!(yaml_map, key)
        cond do
          is_bitstring(value) -> "#{indentation}#{key}: #{value}"
          is_number(value) -> "#{indentation}#{key}: #{value}"
          is_map(value) -> "#{indentation}#{key}:\n#{to_yaml(value, "#{indentation}  ")}"
        end
      end
    )
    |> Enum.join("\n")
end

You use it as follows:

YamlElixir.read_from_file!("file.yaml")
|> Map.put(:some_key, %{some_nested_key: 123})
|> to_yaml

It’s not perfect but it suits my purposes (reading and writing the app.yaml configuration file in Google App Engine).

Thought I’d share to help others who come here while searching, like I did!

Last Post!

7rans

7rans

It actually is standardized, but implementors have taken liberties with it, and some have been reluctant to updated from 1.1 to 1.2. Yes, YAML is complex compared to JSON, but it was designed to cover more use cases. The alternative might have led to multiple ad-hoc solutions sprouting up for those additional features.

Where Next?

Popular in Questions Top

nobody
Hi! In PHP: $_SERVER[‘SERVER_ADDR’] - in Elixir? Searched the docs for ip address and the web, no good results. Thanks!
New
baxterw3b
Hi guys, i’m new in the Elixir world, and i have to say, that i love it! i’m having some problem to understand anonymous functions with ...
New
joaquinalcerro
Hi there, I am working with Ecto-Postgresql and I need to call all of the records from a specific table but the table has 40,000 records...
New
jononomo
For some reason my phoenix channels are working for me in my local dev environment, but as soon as I deploy via Docker, I get a 403 error...
New
Darmani72
If I have a post route which an argument: post /my_post_route/:my_param1, MyController.my_post_handler How would get the post params ...
New
shijith.k
I am trying to start a new phoenix project with elixir 1.9, but mix phx.new does not work. It says that ** (Mix) The task "phx.new" could...
New
SoCreat
i’m a new one to elixir which editor can i use vs code? or atom? Thanks! :smiley:
New

Other popular topics Top

electic
Hi, I am new to Elixir. I am trying to use the DateTime component to insert a date into MySQL however the there seems to be no way to fo...
New
vertexbuffer
Hello, can anybody help here..? I have a list of players and I what to delete an element, but every for loop the list is reverting to ori...
New
greenz1
I have a phoenix application from which a user can download multiple(5-6) files of size 1MB. I couldn’t find anything related to sending ...
New
axelson
This post is a wiki (feel free to hit the edit button near the bottom right of this post to add your own changes!) This post collects co...
239 49084 226
New
msaraiva
Surface is an experimental library built on top of Phoenix LiveView and its new LiveComponent API that aims to provide a more declarative...
564 44139 214
New
Patoshizzle
After calling mix ecto.create I get this error: 17:00:32.162 [error] GenServer #PID&lt;0.412.0&gt; terminating ** (Postgrex.Error) FATAL...
New

We're in Beta

About us Mission Statement