How to handle route not found within a namespace in Rails?

Question

I am trying expose our app via public APIs. I have written API code as an engine and mounted it on my app.

Say I have defined a route /api/users which will be handled by the API engine i have created.

We also have a generic path defined at the end of routes definition which handles all other routes since we use a frontend framework.

If the user misspells the public API as /api/user-detail, it gets handled in the generic path defined.

routes.rb

mount FtApi::Engine => "/api"
match "*a", controller: :assets, action: :index, via: [:get, :post, :patch]

I want to handle any undefined routes error under namespace api within the engine, but the path is captured by wildcard route controller.

How can i handle undefined routes error under namespace api within the Rails engine defined?

Answer 1

You can stop capturing any random route by your wildcard by applying Request-Based Constraints.

For more Info take a look here Request Based Constraints and Advanced Constraints

Take a look at the given below code. Haven't tested this but this is an example how you can add constraints in routes.

match "*a", controller: :assets, action: :index, constraints: RouteConstraint.new, via: [:get, :post, :patch]

And then add this code in constraints or initializers

class RouteConstraint
  def matches?(request)
    not request.path.include?('api')
  end
end