Deprecations in Nova

We try to keep the Nova API as stable as possible, but sometimes we need to depreciate old functionality. This is a list of the things that are currently deprecated in Nova.

0.9.24

• The old format with {Module, Function} is deprecated in favor of fun Module:function/1. This is a breaking change, but it is a good time to do it now before we release 1.0.0. The old format will be removed in 1.0.0. This goes for all occurrences of {Module, Function} in Nova.

Unreleased

• routing_tree is no longer a dependency. Nova's dispatch table is now built by the in-tree nova_routing_trie. If you introspected the routing table by including routing_tree.hrl and matching on #host_tree{}, #routing_tree{}, #node{} or #node_comp{}, those records are gone. Use nova_routing_trie:routes/1, which returns [{Host, Path, Method, HandlerValue}]; the trie itself is opaque.

Nothing changes for applications that only declare routes and let Nova serve them.

Behaviour changes to be aware of

• Route matching backtracks. A request is now matched against every route that could serve it, so /a/:x/c matches /a/b/c even when a /a/b/d route exists. Previously matching committed to the first sibling it found and gave up, returning a 404. Routes that were unreachable before may start being reached.

• Every binding at the same depth is reachable. /p/:id/picture and /p/:user_id/name both work. Previously only whichever one happened to be visited first was reachable, and which one that was depended on insertion order.

• use_strict_routing now takes effect. It never reached the routing table before, so it has been a no-op. An application with genuinely conflicting routes and use_strict_routing set to true will now refuse to start. Conflicts are reported with both paths and the method.

• An application's own status-code routes now win. Nova's routes are compiled last, so a {404, fun my_controller:not_found/1, #{}} entry in your router replaces Nova's default error page. Previously Nova's was registered first and yours was silently ignored.

• Plugins. A route entry that declares plugins uses exactly those, and one that does not uses the globally configured ones - unchanged. The new plugin_strategy option lets you combine both; see the routing guide.

• nova_router:lookup_url/1,2,3 keep their return shapes, including {error, comparator_not_found, AllowedMethods} for a path that exists but does not accept the method.