Provides various encoders/decoders to store values in the string.

Example:

<% {:ok, encoded_value} = Drab.Coder.encode(%{question: "foo", answer: 42}) %>
<button  drab='click:check_answer("<%= encoded_value %>")'>Check answer</button>

defhandler check_answer(socket, sender, value) do
  {:ok, decoded_value} = Drab.Coder.decode(value)

  question = decoded_value[:question]
  answer = decoded_value[:answer]
end

The default encoder is Drab.Coder.Cipher, which encrypts any value and returns the base-64 encoded string. You may change the default encoder with:

config :drab, default_encoder: Drab.Coder.String

Each encoder has two pairs of functions:

• encode/1 / decode/1, returning tuple {:ok, result}
• encode!/1 / decode!/1, returning the result

The result of encode functions is always a string. The argument might be restricted to string (Drab.Coder.URL, Drab.Coder.Base64). Other encoders takes any valid term as an argument.

The argument of decode functions is always a string.

Available encoders:

• Drab.Coder.URL - urlencode, encodes only string
• Drab.Coder.Base64 - simple base-64, encodes string only (no encryption)
• Drab.Coder.String - encodes any term to string, not ciphered
• Drab.Coder.Cipher - encodes any term to an encrypted string (default)

You may use the encoders individually, they expose the same API as Drab.Coder:

iex> {:ok, encoded} = Drab.Coder.String.encode(%{forty_two: 42})
iex> Drab.Coder.String.decode(encoded)
{:ok, %{forty_two: 42}}

It is used in the other part of the application, for example in Drab.Browser.set_cookie/3:

set_cookie(socket, "my_cookie", "42", encode: true) # use default encoder
set_cookie(socket, "my_cookie", "result: 42", encode: Drab.Coder.URL)