Merge pull request #245 from samvera-labs/extendable_query_services

Add an extendable query interface.

lib/valkyrie/persistence/active_fedora/query_service.rb

@@ -29,6 +29,10 @@ def find_references_by(resource:, property:)
       def find_inverse_references_by(resource:, property:)
         Valkyrie::Persistence::ActiveFedora::Queries::FindInverseReferencesQuery.new(resource, property).run
       end
+
+      def custom_queries
+        @custom_queries ||= ::Valkyrie::Persistence::CustomQueryContainer.new(query_service: self)
+      end
     end
   end
 end

valkyrie/lib/valkyrie/persistence.rb

@@ -1,6 +1,7 @@
 # frozen_string_literal: true
 module Valkyrie
   module Persistence
+    require 'valkyrie/persistence/custom_query_container'
     require 'valkyrie/persistence/memory'
     require 'valkyrie/persistence/postgres'
     require 'valkyrie/persistence/solr'

valkyrie/lib/valkyrie/persistence/custom_query_container.rb

@@ -0,0 +1,28 @@
+# frozen_string_literal: true
+module Valkyrie::Persistence
+  class CustomQueryContainer
+    attr_reader :query_service, :query_handlers
+    def initialize(query_service:)
+      @query_service = query_service
+      @query_handlers = []
+    end
+
+    def register_query_handler(query_handler)
+      @query_handlers << query_handler
+    end
+
+    def method_missing(meth_name, *args, &block)
+      query_handler = find_query_handler(meth_name).new(query_service: query_service)
+      return super unless query_handler
+      query_handler.__send__(meth_name, *args, &block)
+    end
+
+    def find_query_handler(method)
+      query_handlers.find { |x| x.queries.include?(method) }
+    end
+
+    def respond_to_missing?(meth_name, _args)
+      find_query_handler(meth_name).present?
+    end
+  end
+end

valkyrie/lib/valkyrie/persistence/fedora/query_service.rb

@@ -76,5 +76,9 @@ def find_inverse_references_by(resource:, property:)
         find_by(id: id)
       end
     end
+
+    def custom_queries
+      @custom_queries ||= ::Valkyrie::Persistence::CustomQueryContainer.new(query_service: self)
+    end
   end
 end

valkyrie/lib/valkyrie/persistence/memory/query_service.rb

@@ -1,12 +1,13 @@
 # frozen_string_literal: true
 module Valkyrie::Persistence::Memory
   class QueryService
-    attr_reader :adapter
+    attr_reader :adapter, :query_handlers
     delegate :cache, to: :adapter
     # @param adapter [Valkyrie::Persistence::Memory::MetadataAdapter] The adapter which
     #   has the cache to query.
     def initialize(adapter:)
       @adapter = adapter
+      @query_handlers = []
     end
 
     # @param id [Valkyrie::ID] The ID to query for.
@@ -82,5 +83,9 @@ def find_parents(resource:)
     def member_ids(resource:)
       resource.member_ids || []
     end
+
+    def custom_queries
+      @custom_queries ||= ::Valkyrie::Persistence::CustomQueryContainer.new(query_service: self)
+    end
   end
 end

valkyrie/lib/valkyrie/persistence/postgres/query_service.rb

@@ -81,5 +81,9 @@ def find_references_query
         JOIN orm_resources member ON (b.member->>'id')::uuid = member.id WHERE a.id = ?
       SQL
     end
+
+    def custom_queries
+      @custom_queries ||= ::Valkyrie::Persistence::CustomQueryContainer.new(query_service: self)
+    end
   end
 end

valkyrie/lib/valkyrie/persistence/solr/query_service.rb

@@ -44,5 +44,9 @@ def find_references_by(resource:, property:)
     def find_inverse_references_by(resource:, property:)
       Valkyrie::Persistence::Solr::Queries::FindInverseReferencesQuery.new(resource: resource, property: property, connection: connection, resource_factory: resource_factory).run
     end
+
+    def custom_queries
+      @custom_queries ||= ::Valkyrie::Persistence::CustomQueryContainer.new(query_service: self)
+    end
   end
 end

valkyrie/lib/valkyrie/specs/shared_specs/queries.rb

@@ -125,4 +125,26 @@ class SecondResource < Valkyrie::Resource
       expect(query_service.find_parents(resource: child1).to_a).to eq []
     end
   end
+
+  describe ".register_query_handler" do
+    it "can register a query handler" do
+      class QueryHandler
+        def self.queries
+          [:find_by_user_id]
+        end
+
+        attr_reader :query_service
+        def initialize(query_service:)
+          @query_service = query_service
+        end
+
+        def find_by_user_id
+          1
+        end
+      end
+      query_service.custom_queries.register_query_handler(QueryHandler)
+      expect(query_service.custom_queries).to respond_to :find_by_user_id
+      expect(query_service.custom_queries.find_by_user_id).to eq 1
+    end
+  end
 end