Fallback Routing with Axum

#axum #rust #webdev #routing

Yesterday I ran into a small problem with my Axum routing for my blog. So today I wanted to take 10 minutes and do quick write up about it!

My blog uses Axum as its Web Framework of choice. I was looking through some old emails and found one where a reader reached out about a post I made! (It was this one about FZF Spell Checking in VIM)

But I realized that it was linking to an older URL format, The link was to https://coreyja.com/blog/2018/11/10/vim-spelling-suggestions-fzf.html!

And you can see I was using a different URL structure then, and my current blog didn't have a redirect setup!

And that was our goal! I wanted https://coreyja.com/blog/2018/11/10/vim-spelling-suggestions-fzf.html to redirect to /posts/vim-spelling-suggestions-fzf. And I also decided that I wanted blog/anything-else-here to redirect to /posts

Simple enough!

I added these two routes to my Axum Router function:

.route("/blog/:year/:month/:date/:slug", get(redirect_to_new_post_url))
.route("/blog/*catchall", get(redirect_to_posts_index))

And I expected this to work out of the box! But it didn't :sadnerd:

Instead I got an error about conflicting routes. Luckily the answer is relatively easy, at least in my case! I just needed to use nest to target all the /blog urls and then use a fallback. Here is what I ended up with!

.nest(
  "/blog",
  Router::new()
    .route("/:year/:month/:date/:slug", get(redirect_to_new_post_url))
    .fallback(redirect_to_posts_index)
)

And now I was able to get all the redirects working as I wanted! Go check out that 'old' URL above now and with any luck you should be redirected to the right post!