The storage adapter specification for WeChat common application.

Since we need to temporarily storage some key data(e.g. access_token) for invoking WeChat APIs, this module is used for customizing the persistence when use elixir_wechat in the centralization nodes(hereinafter "hub") side of WeChat common application.

Notice: the scenario as a hub, we need to implement the completed functions to maintain the persistence.

Writing custom storage adapter

Example for WeChat Official Account Platform application

defmodule MyAppStorageHub do
  @behaviour WeChat.Storage.Hub

  @impl true
  def fetch_secret_key(appid, args) do
    secret_key = "Get secret_key by appid from your persistence..."
    secret_key
  end

  @impl true
  def fetch_access_token(appid, args) do
    access_token = "Get access_token by appid from your persistence..."
    {:ok, %WeChat.Token{access_token: access_token}}
  end

  @impl true
  def fetch_ticket(appid, type, args) do
    ticket = "Get ticket by appid from your persistence..."
    {:ok, ticket}
  end

  @impl true
  def refresh_access_token(appid, access_token, args) do
    access_token = "Refresh access_token by appid from your persistence..."
    {:ok, %WeChat.Token{access_token: access_token}}
  end

  @impl true
  def save_access_token(appid, access_token, args) do
    # Save access_token by appid to your persistence
  end

  @impl true
  def save_ticket(appid, ticket, type, args) do
    # Save ticket by appid to your persistence
  end
end

Use MyAppStorageHub

Global configure MyAppStorageHub

defmodule Client do
  use WeChat,
    adapter_storage: {MyAppStorageHub, args}
end

defmodule Client do
  use WeChat,
    adapter_storage: MyAppStorageHub
end

Dynamically set MyAppStorageHub when call WeChat.request/2

WeChat.request(:post, url: ..., adapter_storage: {MyAppStorageHub, args}, ...)
WeChat.request(:post, url: ..., adapter_storage: MyAppStorageHub, ...)

Notice: The above args will be returned back into each implement of callback function, if not input it, args will be as an empty list in callback.