pedestal.views

Server-side rendering interceptors.

Quickstart

Add the following dependency to project.clj or build.boot:

[com.cognitect/pedestal.views "0.1.0-SNAPSHOT"]

Require the namespace in your Pedestal service.clj (or wherever else you define your routes.):

(:require [com.cognitect.pedestal.views :as views])

Add the view rendering interceptor to the route or routes that need it:

(def common-interceptors [(body-params/body-params) http/html-body views/renderer])

(def routes
  #{["/home"  :get (conj common-interceptors `home)]
    ["/about"   :get (conj common-interceptors `about)]})

Now you can separate view rendering from logic & data assembly.

(defn about
  [request]
  {:view :sample.views/about
   :text "About"
   :body (clojure-version)
   :url  (route/url-for ::about)})

(defn home
  [request]
  {:view :sample.views/home
   :text "Rendered by pedestal.views"
   :body "Hello, world!"
   :url  (route/url-for ::home)})

Details

The interceptor com.cognitect.pedestal.views/renderer uses the :view key to look up a rendering function. The value can be a keyword for ease of use... the interceptor looks for a function with the "same" name as the keyword. The value of the :view key can also be a symbol or var, in which case lookup proceeds as you would expect.

The interceptor passes the entire response map to the rendering function. That means applications can use whatever keys and nesting structure makes sense for the application.

Rendering functions are supplied by a variety of templating libraries. We've tried this out with:

• Enlive
• Hiccup
• Stencil

Since they all meet at the level of "make me a function" they all work nicely.

The interceptor should also work with any of the other packages listed as Template Languages.

Using with Vase

Pedestal.views offers some interceptor literals that work with a Vase descriptor.

Engine

Literal syntax:

;; Use default engine.
;; View keys are keywords that name functions
#views/engine{}

;; Use Stencil.
;; View keys map to template .mustache files.
#views/engine{:engine-type :stencil}

;; Use Selmer
;; View keys map to template .html files.
#views/engine{:engine-type :selmer}

An engine must either be added to the #vase/interceptors key or supplied by your driver application. This is equivalent to the function com.cognitect.pedestal.views/renderer or the corresponding constructors in the selmer.clj and stencil.clj namespaces.

Note that you are not required to include Stencil or Selmer in your project's dependencies. If you have them, then these engine options will work. If you don't have them, then you'll get exceptions.

Render

Literal syntax:

;; Simple case: always render the same view
#views/render{:view :home}

#views/render - Goes in any route action vector. Attaches a view key to the response for rendering on the way out of the interceptor stack for that route. Can follow a #vase/query or #vase/transact interceptor to display the results.

;; When using Stencil, renders "home.mustache"
#views/render{:view :home}

;; When using Selmer, renders "home.html"
#views/render{:view :home}

;; When using the default engine, renders `sample.app/home`
#views/render{:view :sample.app/home}

License

Copyright 2017 Cognitect, Inc.

Distributed under the Eclipse Public License version 1.0.