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Trails & Ways: A Look at Rails Routing

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Trails & Ways: A Look at Rails Routing AbacusWell-nighTrails & Ways: A Look at Rails Routing Mar 25, 2014 Touch things with consideration and they will be yours. Infinite Jest   Our routes are the neuronal connections of our applications. They are the bridges between our users and our data, and pinpoint the interactions that our applications are capable of. Yet, beginners often describe routing to be frustrating; an uncertain process that often goes haywire . Some, in frustration, swear off generated routes entirely, choosing to yank their routes by hand. Having read through the Rails Routing guide last week, I wanted to highlight a few particularly striking features of Rails routing, and suggest that the proper using of these tools will indulge you to yank your routes with greater finesse, control, and accuracy. Nested Resources Most of us are enlightened of the resources :posts method in Rails, which, if widow in the config/routes.rb file, will rationalization Rails to yank the “seven RESTful routes” of index, new, create, show, edit, update, and destroy. This works well for self-sustaining resources, but what if your domain model is increasingly complex, and needs to support nested resources? Nested Resources to the rescue. Rails supports the nesting of resources via the pursuit syntax: resources :posts do resources :comments end Including this in your routes.rb file will tell Rails to yank 14 routes, seven for each resource, with the nested resource coming without the first-level resource in the URI. Ex: http://www.example.com/posts/1/comments/3/edit You can theoretically nest resources to infinite depth, but the Rails guide explicitly discourages nesting increasingly than three resources deep – suggesting that perhaps, if such nesting seems necessary, that you should reconsider your site’s design. Controller Namespaces and Routing Now, say you’d like the goody of nested URIs, but without all the headache of unquestionably creating new resources? Or, you’d like to separate a resource into two sort of “virtual” resources, which use the same model but are accessed via variegated URIs? Namespaces to the rescue! This full-length behaves quite similarly to nested resources, and accepts the pursuit syntax: namespace :admin do resources :posts end This will yank routes like http://www.example.com/admin/posts/new These routes can coexist with those at  http://www.example.com/posts which creates the possibility of two separate controllers, with variegated methods, both writing and reading from the same Post model. Restricting the Routes Created Much hullaballoo has been made at Flatiron on the relative pros and cons of the über-powerful “rails generate scaffold” command. In one corner, there are those who enjoy the worthiness to stuff a project with a fully-stocked pantry of routes and controllers. In the other, there are those of increasingly sober caution, who worry well-nigh their projects stuff strangled in a jungle of superfluity. Rails, of course, allows for compromise. Using the “only” and “except” macros, it becomes possible to exert a preferably stratum of tenancy over the unusually Rails generators, making drawing routes downright relaxing. Ex: resources :posts only: [:new, :show, :destroy] or resources :posts except: [:index] These macros will restrict the routes drawn, permitting us the benefits of the Rails generators, without the excess. (You will have to delete the deportment from the controllers manually, I believe). As an aside, having some neuroscience background, the parallels between this sort of “pruning” and the process of neurogenesis are striking – the idea that you first yank many increasingly routes than you could possibly need, and prune downwards, as opposed to only towers what you need as you need it. Perhaps I’m reading increasingly into the metaphor than the substance justifies, but it’s an heady idea.Increasinglyon this concept here. Segment Constraints Perhaps my favorite routing feature. Segment constraints indulge you to pinpoint regular expressions which filter through URIs when matching your routes. Ex: get '/:id', to: 'posts#show', constraints: { id: /\d.+/ } get '/:username', to: 'users#show' What’s tomfool well-nigh this is that, since routes are evaluated in the order they are defined, segment constraints indulge you to create a “cascade” of possible routes within a single namespace. In the whilom example, any value which satisfied the constraint of stuff numeric would’ve been unprotected by the first route and been directed to posts#show, while any alphabetical values would’ve passed the first route and been captured by the second, going to users#show. In clever hands, this technique could be quite powerful. There are many other special features of Rails routing, but these were the most striking and seemed to have the most non-contrived potential. Good luck! Comments Please enable JavaScript to view the comments powered by Disqus. Abacus Abacus kronovet@gmail.com kronosapiens kronosapiens I'm Daniel Kronovet, a data scientist living in Tel Aviv.