Created
June 15, 2018 16:56
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| defmodule MyApp.ActivationToken do | |
| import Ecto.Query | |
| alias MyApp.Accounts.User | |
| alias MyApp.Repo | |
| @moduledoc """ | |
| Responsible for generating uniuqe email activation tokens | |
| """ | |
| @length 64 | |
| @query_limit 5 | |
| @doc """ | |
| Generates a unique random string for email activation | |
| """ | |
| def generate(acc \\ 0) do | |
| @length | |
| |> :crypto.strong_rand_bytes | |
| |> Base.url_encode64 | |
| |> binary_part(0, @length) | |
| |> enforce_uniqueness(acc) | |
| end | |
| # Passes the generated token down to `is_unique?` and handles | |
| # the result by either returning the token if unique, or calling | |
| # generate again for another attempt at a unique token | |
| defp enforce_uniqueness(token, acc) do | |
| if acc >= @query_limit do | |
| raise "Error. Something has gone terribly wrong in token generation" | |
| end | |
| case is_unique?(token) do | |
| true -> token | |
| _ -> generate(acc + 1) | |
| end | |
| end | |
| # Passes the generated token down to `users_with_token` and | |
| # verifies that the list returned is less than 1, returning | |
| # a boolean | |
| defp is_unique?(token) do | |
| Enum.count(users_with_token(token)) <= 0 | |
| end | |
| # Queries the database for users whose activation token matches | |
| # the newly generated one. Returns a list of those users | |
| defp users_with_token(token) do | |
| Repo.all( | |
| from u in User, | |
| where: u.activation_token == ^token | |
| ) | |
| end | |
| end |
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