Add `show_many' action helper

README.md

@@ -187,7 +187,7 @@ helpers, and the `resource`, `has_one`, and `has_many` keywords build
 [Sinatra::Namespace][21] blocks. You can manage caching directives, set
 headers, and even `halt` (or `not_found`, although such cases are usually
 handled transparently by returning `nil` values or empty collections from
-action helpers) as desired.
+action helpers) as appropriate.
 
 ```ruby
 class App < Sinatra::Base
@@ -541,6 +541,11 @@ Return an array of zero or more objects to serialize on the response.
 Take an ID and return the corresponding object (or `nil` if not found) to
 serialize on the response.
 
+##### `show_many {|ids| ..}` => Array
+
+Take an array of IDs and return an equally-lengthed array of objects to
+serialize on the response. See "Coalesced Find Requests" below.
+
 ##### `create {|attr, id| ..}` => id, Object?
 
 With client-generated IDs: Take a hash of (dedasherized) attributes and a
@@ -1116,7 +1121,7 @@ either `graft` or `create`.
 
 `create` and `update` are the only two action helpers that trigger sideloading;
 `graft`, `merge`, and `clear` are the only action helpers invoked by
-sideloading.  You must indicate which combinations are valid using the
+sideloading. You must indicate which combinations are valid using the
 `:sideload_on` action helper option. (Note that if you want to sideload `merge`
 on `update`, you must define a `clear` action helper as well.) For example:
 
@@ -1251,6 +1256,11 @@ are supported: `?filter[id]=1,2` and `?filter[id][]=1&filter[id][]=2`. If any
 ID is not found (i.e. `show` returns `nil`), the route will halt with HTTP
 status 404.
 
+Optionally, to reduce round trips to the database, you may define a "special"
+`show_many` action helper that takes an array of IDs to show. It does not take
+`:roles` or any other options and will only be invoked if the current user has
+access to `show`. This feature is still experimental.
+
 ### Patchless Clients
 
 {json:api} [recommends][23] supporting patchless clients by using the

demo-app/classes/author.rb

@@ -55,6 +55,10 @@ def settable_fields
 
   show
 
+  show_many do |ids|
+    Author.where(id: ids.map!(&:to_i)).all
+  end
+
   index do
     Author.dataset
   end

demo-app/classes/post.rb

@@ -59,6 +59,10 @@ def settable_fields
     next find(slug), include: %w[author comments tags]
   end
 
+  show_many do |slugs|
+    next Post.where(slug: slugs.map!(&:to_s)).all, include: %i[author tags]
+  end
+
   index do
     Post.dataset
   end

lib/sinja/config.rb

@@ -70,7 +70,7 @@ def initialize
       @error_logger = ->(h) { logger.error('sinja') { h } }
 
       @default_roles = {
-        :resource=>RolesConfig.new(%i[show index create update destroy]),
+        :resource=>RolesConfig.new(%i[show show_many index create update destroy]),
         :has_many=>RolesConfig.new(%i[fetch merge subtract clear]),
         :has_one=>RolesConfig.new(%i[pluck graft prune])
       }

lib/sinja/resource.rb

@@ -34,14 +34,16 @@ def def_action_helper(context, action, allow_opts=[])
         required_arity = {
           :create=>2,
           :index=>-1,
-          :fetch=>-1
+          :fetch=>-1,
+          :show_many=>-1
         }.freeze[action] || 1
 
         define_method(action) do |*args|
           raise ArgumentError, "Unexpected argument(s) for `#{action}' action helper" \
             unless args.length == block.arity
 
-          public_send("before_#{action}", *args) if respond_to?("before_#{action}")
+          public_send("before_#{action}", *args) \
+            if respond_to?("before_#{action}")
 
           case result = instance_exec(*args, &block)
           when Array

lib/sinja/resource_routes.rb

@@ -3,6 +3,7 @@ module Sinja
   module ResourceRoutes
     def self.registered(app)
       app.def_action_helper(app, :show, :roles)
+      app.def_action_helper(app, :show_many)
       app.def_action_helper(app, :index, %i[roles filter_by sort_by])
       app.def_action_helper(app, :create, :roles)
       app.def_action_helper(app, :update, :roles)
@@ -15,16 +16,23 @@ def self.registered(app)
       app.get '', :qcapture=>{ :filter=>:id }, :qparams=>%i[include fields], :actions=>:show do
         ids = @qcaptures.first # TODO: Get this as a block parameter?
         ids = ids.split(',') if String === ids
+        ids = [*ids].tap(&:uniq!)
 
-        opts = {}
-        resources = [*ids].tap(&:uniq!).map! do |id|
-          tmp, opts = show(id)
-          raise NotFoundError, "Resource '#{id}' not found" unless tmp
-          tmp
-        end
+        if respond_to?(:show_many)
+          resources, opts = show_many(ids)
+          raise NotFoundError, "Resource(s) not found" \
+            unless ids.length == resources.length
+          serialize_models(resources, opts)
+        else
+          opts = {}
+          resources = ids.map! do |id|
+            tmp, opts = show(id)
+            raise NotFoundError, "Resource '#{id}' not found" unless tmp
+            tmp
+          end
 
-        # TODO: Serialize collection with opts from last model found?
-        serialize_models(resources, opts)
+          serialize_models(resources, opts)
+        end
       end
 
       app.head '' do

test/integration/author_test.rb

@@ -10,6 +10,48 @@ def app
     Sinatra::Application.new
   end
 
+  def test_uncoalesced_find_head
+    head '/authors'
+    assert_ok
+    assert_equal 'GET,POST', last_response.headers['Allow']
+  end
+
+  def test_uncoalesced_find
+    DB[:authors].multi_insert [
+      { :email=>'[email protected]', :display_name=>'Dilbert' },
+      { :email=>'[email protected]', :display_name=>'Dogbert' },
+      { :email=>'[email protected]', :display_name=>'Catbert' },
+      { :email=>'[email protected]', :display_name=>'Wally' }
+    ]
+    get '/authors'
+    assert_ok
+    vals = json[:data].map do |t|
+      name = t[:attributes][:'display-name']
+      name = nil if name == 'Anonymous Coward'
+      { :id=>t[:id].to_i, :display_name=>name }
+    end
+    assert_equal DB[:authors].select(:id, :display_name).all, vals
+  end
+
+  def test_coalesced_find_head
+    head '/tags?filter[id]=2,4'
+    assert_ok
+    assert_equal 'GET', last_response.headers['Allow']
+  end
+
+  def test_coalesced_find
+    DB[:authors].multi_insert [
+      { :email=>'[email protected]', :display_name=>'Dilbert' },
+      { :email=>'[email protected]', :display_name=>'Dogbert' },
+      { :email=>'[email protected]', :display_name=>'Catbert' },
+      { :email=>'[email protected]', :display_name=>'Wally' }
+    ]
+    get '/authors?filter[id]=2,4'
+    assert_ok
+    vals = json[:data].map { |t| { :id=>t[:id].to_i, :display_name=>t[:attributes][:'display-name'] } }
+    assert_equal DB[:authors].where(:id=>[2, 4]).select(:id, :display_name).all, vals
+  end
+
   def test_disallow_client_generated_id
     post '/authors', JSON.generate(:data=>{
       :type=>'authors',

test/integration/tag_test.rb

@@ -7,7 +7,6 @@ class PostTest < SequelTest
   include Rack::Test::Methods
 
   def app
-    Sinatra::Application.dump_errors = true
     Sinatra::Application.new
   end