Hi everyone! I’m trying to find a way to add a default value on a route param in Phoenix. I’ve searched in the forum but couldn’t find an exact match to what I’m seeking.

Example: Let’s suppose there’s a page that shows logs that can be filtered. A user could click an option to filter logs from 7 days up to 30 days and we’d have routes like:

get "/logs", LogController, :index`

• /logs?days=7
• /logs?days=30

This is very trivial to achieve because any query parameter is matched against this route, but what if I want to make the days param optional? In other words, filling the value if the user does not specify one.

I know we could simply do that by hand merging the conn.params values with a default map after the action was already matched, but the problem with this approach is that the route won’t change to represent the current page state. If I want to always filter logs that are 1 day old by default, when the user accesses the /logs page, it would have to automatically fill the params as /logs?days=1.

I don’t work with Rails, but it seems that it has similar functionality to other frameworks that I’ve used before: Rails Routing from the Outside In — Ruby on Rails Guides.
So, I was wondering if Phoenix has something like this built-in or its necessary to create a custom plug.