🐥 Assigning values from a map to a socket in Elixir Phoenix

To assign the keys of the map to a socket in Elixir using the assign/3 function, you can use Enum.reduce/3 to iterate through the map and update the socket with each key-value pair.

Let's see how that works. Imagine you have this map as the source:

map = %{
  app_env: Application.fetch_env!(:my_app, :app_env),
  app_name: Application.fetch_env!(:my_app, :app_name),
  app_description: Application.fetch_env!(:my_app, :app_description),
  app_url: MapAppWeb.Endpoint.url(),
  search_term: ""
}

If we want to assign each key with its corresponding value to the socket, you can use Enum.reduce/3 for doing so:

socket = Enum.reduce(map, socket, fn {key, value}, acc_socket ->
  assign(acc_socket, key, value)
end)

There is a shortcut to do this by using the assign/2 function:

assign(socket, map)

This is essentially the same as doing:

socket
|> assign(:app_env, map.app_env)
|> assign(:app_name, map.app_name)
|> assign(:app_description, map.app_description)
|> assign(:app_url, map.app_url)
|> assign(:search_term, map.search_term)

Update: It looks like I made things too complicated. The Phoenix.Component.assign/2 function basically does the same thing. When using it with a connection, you can use Plug.Conn.merge_assigns/2 function. I've updated the code with this shortcut. Thanks to namxam.bsky.social and Michal for pointing this out.