Merge pull request #89 from lotus/params-get

Introduced Lotus::Action::Params#get

lib/lotus/action/params.rb

@@ -26,6 +26,14 @@ class Params
       # @since 0.1.0
       ROUTER_PARAMS = 'router.params'.freeze
 
+      # Separator for #get
+      #
+      # @since x.x.x
+      # @api private
+      #
+      # @see Lotus::Action::Params#get
+      GET_SEPARATOR = '.'.freeze
+
       # Whitelist and validate a parameter
       #
       # @param name [#to_sym] The name of the param to whitelist
@@ -137,6 +145,52 @@ def [](key)
         @attributes.get(key)
       end
 
+      # Get an attribute value associated with the given key.
+      # Nested attributes are reached with a dot notation.
+      #
+      # @param key [String] the key
+      #
+      # @return [Object,NilClass] return the associated value, if found
+      #
+      # @since x.x.x
+      #
+      # @example
+      #   require 'lotus/controller'
+      #
+      #   module Deliveries
+      #     class Create
+      #       include Lotus::Action
+      #
+      #       params do
+      #         param :customer_name
+      #         param :address do
+      #           param :city
+      #         end
+      #       end
+      #
+      #       def call(params)
+      #         params.get('customer_name')   # => "Luca"
+      #         params.get('uknown')          # => nil
+      #
+      #         params.get('address.city')    # => "Rome"
+      #         params.get('address.unknown') # => nil
+      #
+      #         params.get(nil)               # => nil
+      #       end
+      #     end
+      #   end
+      def get(key)
+        key, *keys = key.to_s.split(GET_SEPARATOR)
+        result     = self[key]
+
+        Array(keys).each do |k|
+          break if result.nil?
+          result = result[k]
+        end
+
+        result
+      end
+
       # Returns the Ruby's hash
       #
       # @return [Hash]

test/action/params_test.rb

@@ -155,25 +155,6 @@
   end
 
   describe 'validations' do
-    before do
-      TestParams = Class.new(Lotus::Action::Params) do
-        param :email, presence:   true, format: /\A.+@.+\z/
-        param :name,  presence:   true
-        param :tos,   acceptance: true
-        param :age,   type: Integer
-        param :address do
-          param :line_one, presence: true
-          param :deep do
-            param :deep_attr, type: String
-          end
-        end
-      end
-    end
-
-    after do
-      Object.send(:remove_const, :TestParams)
-    end
-
     it "isn't valid with empty params" do
       params = TestParams.new({})
 
@@ -228,6 +209,60 @@
     end
   end
 
+  describe '#get' do
+    describe 'with data' do
+      before do
+        @params = TestParams.new(name: 'John', address: { line_one: '10 High Street', deep: { deep_attr: 1 } })
+      end
+
+      it 'returns nil for nil argument' do
+        @params.get(nil).must_be_nil
+      end
+
+      it 'returns nil for unknown param' do
+        @params.get('unknown').must_be_nil
+      end
+
+      it 'allows to read top level param' do
+        @params.get('name').must_equal 'John'
+      end
+
+      it 'allows to read nested param' do
+        @params.get('address.line_one').must_equal '10 High Street'
+      end
+
+      it 'returns nil for uknown nested param' do
+        @params.get('address.unknown').must_be_nil
+      end
+    end
+
+    describe 'without data' do
+      before do
+        @params = TestParams.new({})
+      end
+
+      it 'returns nil for nil argument' do
+        @params.get(nil).must_be_nil
+      end
+
+      it 'returns nil for unknown param' do
+        @params.get('unknown').must_be_nil
+      end
+
+      it 'returns nil for top level param' do
+        @params.get('name').must_be_nil
+      end
+
+      it 'returns nil for nested param' do
+        @params.get('address.line_one').must_be_nil
+      end
+
+      it 'returns nil for uknown nested param' do
+        @params.get('address.unknown').must_be_nil
+      end
+    end
+  end
+
   describe '#to_h' do
     let(:params) { Lotus::Action::Params.new(id: '23') }
 

test/fixtures.rb

@@ -603,6 +603,19 @@ def call(params)
   end
 end
 
+class TestParams < Lotus::Action::Params
+  param :email, presence:   true, format: /\A.+@.+\z/
+  param :name,  presence:   true
+  param :tos,   acceptance: true
+  param :age,   type: Integer
+  param :address do
+    param :line_one, presence: true
+    param :deep do
+      param :deep_attr, type: String
+    end
+  end
+end
+
 class Root
   include Lotus::Action