[FEAT] Functionality to dynamically add routes (#274)

guides/routing.md

@@ -105,3 +105,23 @@ It's possible to configure a small set of endpoints with a specific plugin. This
 
 In the example above we have enabled the *pre-request*-plugin `nova_json_schemas` for all routes under the `/admin` prefix. This will cause all requests to be validated against the JSON schema defined in the `nova_json_schemas` plugin.
 You can also include *post-request*-plugins in the same way.
+
+
+## Adding routes programatically
+
+You can also add routes programatically by calling `nova_router:add_route/2`. This is useful if you want to add routes dynamically. The spec for it is:
+
+```erlang
+%% nova_router:add_route/2 specification
+-spec add_route(App :: atom(), Routes :: map() | [map()]) -> ok.
+```
+
+First argument is the application you want to add the route to. The second argument is the route or a list of routes you want to add - it uses the same structure as in the regular routers.
+
+```erlang
+nova_router:add_route(my_app, #{prefix => "/admin", routes => [{"/", {my_controller, main}, #{methods => [get]}}]}).
+```
+
+This will add the routes defined in the second argument to the `my_app` application.
+
+**Note**: If a route already exists it will be overwritten.

src/controllers/nova_error_controller.erl

@@ -12,7 +12,12 @@ status_code(Req) ->
 not_found(Req) ->
     %% Check the accept-headers
     Accept = cowboy_req:header(<<"accept">>, Req),
-    AcceptList = binary:split(Accept, <<",">>, [global]),
+    AcceptList = case Accept of
+                     undefined ->
+                         [<<"application/json">>];
+                     _ ->
+                         binary:split(Accept, <<",">>, [global])
+                 end,
 
     case {lists:member(<<"application/json">>, AcceptList),
 	  lists:member(<<"text/html">>, AcceptList)} of

src/nova_handler.erl

@@ -8,7 +8,7 @@
         ]).
 
 -include_lib("kernel/include/logger.hrl").
--include("nova_router.hrl").
+-include("../include/nova_router.hrl").
 
 -callback init(Req, any()) -> {ok | module(), Req, any()}
                                   | {module(), Req, any(), any()}

src/nova_router.erl

@@ -24,12 +24,15 @@
          render_status_page/5,
 
          %% Expose the router-callback
-         routes/1
+         routes/1,
+
+         %% Modulates the routes-table
+         add_routes/2
         ]).
 
 -include_lib("routing_tree/include/routing_tree.hrl").
 -include_lib("kernel/include/logger.hrl").
--include("nova_router.hrl").
+-include("../include/nova_router.hrl").
 
 -type bindings() :: #{binary() := binary()}.
 -export_type([bindings/0]).
@@ -118,6 +121,42 @@ lookup_url(Host, Path, Method) ->
 lookup_url(Host, Path, Method, Dispatch) ->
     routing_tree:lookup(Host, Path, Method, Dispatch).
 
+%%--------------------------------------------------------------------
+%% @doc
+%% Add routes to the dispatch-table for the given app. The routes
+%% can be either a list of maps or a map. It use the same structure as
+%% the routes-callback in the router-module.
+%% @end
+%%--------------------------------------------------------------------
+-spec add_routes(App :: atom(), Routes :: [map()] | map()) -> ok.
+add_routes(_App, []) -> ok;
+add_routes(App, [Routes|Tl]) when is_list(Routes) ->
+    Options = #{},
+    StorageBackend = application:get_env(nova, dispatch_backend, persistent_term),
+    Dispatch = StorageBackend:get(nova_dispatch),
+
+    %% Take out the prefix for the app and store it in the persistent store
+    CompiledApps = StorageBackend:get(?NOVA_APPS, []),
+    CompiledApps0 =
+        case lists:keyfind(App, 1, CompiledApps) of
+            false ->
+                [{App, maps:get(prefix, Options, "/")}|CompiledApps];
+            _StoredApp ->
+                CompiledApps
+        end,
+
+    Options1 = Options#{app => App},
+
+    {ok, Dispatch1, _Options2} = compile_paths(Routes, Dispatch, Options1),
+
+    StorageBackend:put(?NOVA_APPS, CompiledApps0),
+    StorageBackend:put(nova_dispatch, Dispatch1),
+
+    add_routes(App, Tl);
+add_routes(App, Routes) ->
+    add_routes(App, [Routes]).
+
+
 %%%%%%%%%%%%%%%%%%%%%%%%
 %% INTERNAL FUNCTIONS %%
 %%%%%%%%%%%%%%%%%%%%%%%%
@@ -275,6 +314,7 @@ parse_url(Host, [{Path, {Mod, Func}, Options}|Tl], Prefix,
 
     RealPath = case Path of
                    _ when is_list(Path) -> string:concat(Prefix, Path);
+                   _ when is_binary(Path) -> string:concat(Prefix, binary_to_list(Path));
                    _ when is_integer(Path) -> Path;
                    _ -> throw({unknown_path, Path})
                end,