# NavigationHistory [](https://travis-ci.org/danhper/plug-navigation-history) [](https://hex.pm/packages/navigation_history) [](https://hexdocs.pm/navigation_history/SecurePassword.html)
A plug to keep track of user navigation history using sessions.
This can be useful for example to redirect the user back to the previous page,
or to redirect after a login when the user tried to access a page without being
authenticated.
## Installation
Add `navigation_history` to your list of dependencies in `mix.exs`:
```elixir
def deps do
[{:navigation_history, "~> 0.3"}]
end
```
## Usage
To keep track of the navigation, add the `NavigationHistory.Tracker` plug.
For example, in a Phoenix application, your pipeline could become:
```elixir
pipeline :browser do
plug :accepts, ["html"]
plug :fetch_session
plug :fetch_flash
plug :protect_from_forgery
plug :put_secure_browser_headers
plug NavigationHistory.Tracker
end
```
You can then retrieve the paths the user navigated to by using
```elixir
NavigationHistory.last_path(conn) # will return the last navigated path or nil
NavigationHistory.last_path(conn, 1) # will return the second last navigated path
NavigationHistory.last_path(conn, default: "/") # will return the last path or "/"
NavigationHistory.last_paths(conn) # will return a list of the last navigated paths
```
For example, to redirect the user to the last navigated path in Phoenix, you can use
a helper like this
```elixir
def redirect_back(conn, opts \\ []) do
Phoenix.Controller.redirect(conn, to: NavigationHistory.last_path(conn, opts))
end
# you can then write
redirect_back(conn, default: "/")
```
Take a look at [this conversation](https://github.com/phoenixframework/phoenix/pull/1402) in Phoenix for more info about redirecting back.
## Configuration
There are a few options that can be used with the plug:
* `excluded_paths` - The list of paths which should not be tracked.
For example, `/login` or similar for a lot of apps.
Defaults to `[]`
* `included_paths` - Limits list the paths to be tracked when set.
`excluded_paths` is ignored if set.
* `methods` - The list methods which should be tracked.
Defaults to `["GET"]`
* `history_size` - The number of history entries to track in `last_paths`.
Defaults to `10`.
* `key` - The key used to track the navigation.
It can also be passed to `last_path` and `last_paths` to retrieve the paths for the
relevant key.
Defaults to `"default"`.
* `accept_duplicates` - By default, if the same URL is repeated, it is ignored, unless this
option is set to `true`.
Defaults to `false`.
### Example
```elixir
plug NavigationHistory.Tracker, excluded_paths: ["/login", ~r(/admin.*)]
plug NavigationHistory.Tracker, included_paths: [~r(/admin.*)], key: "admin", history_size: 5
# which an be used
NavigationHistory.last_path(conn) # from default history
NavigationHistory.last_path(conn, key: "admin") # from admin history
```
