Allow custom model calculation methods (#150)

* Initial implementation of custom calculation methods * Use `#klass` to get the model * Move test to be database specific Custom model methods doesn't work specifically on Array objects * Simplify test case and example * Clean up methods to remove usage of `try` * Avoid floats by using a count calculation * Refactor checking of calculation methods Break into a separate class to avoid conflicting with existing ActiveRecord methods via `method_missing?` * Simplify test case by removing distinct * Add tests for alternate scenarios - calc method not white listed - calc method white listed but not defined * Specify a RuntimeError for Rails 4.0 tests

Allow custom model calculation methods (#150)
* Initial implementation of custom calculation methods * Use `#klass` to get the model * Move test to be database specific Custom model methods doesn't work specifically on Array objects * Simplify test case and example * Clean up methods to remove usage of `try` * Avoid floats by using a count calculation * Refactor checking of calculation methods Break into a separate class to avoid conflicting with existing ActiveRecord methods via `method_missing?` * Simplify test case by removing distinct * Add tests for alternate scenarios - calc method not white listed - calc method white listed but not defined * Specify a RuntimeError for Rails 4.0 tests
Charles Maresh · Andrew Kane
1 parent 166605c3
Showing 2 changed files with 67 additions and 4 deletions Show diff stats
lib/groupdate/series.rb
test/test_helper.rb
@@ -5,14 +5,14 @@ module Groupdate
     def initialize(magic, relation)
       @magic = magic
       @relation = relation
+      @calculations = Groupdate::Calculations.new(relation)
     end
  
     # clone to prevent modifying original variables
     def method_missing(method, *args, &block)
-      # https://github.com/rails/rails/blob/master/activerecord/lib/active_record/relation/calculations.rb
-      if ActiveRecord::Calculations.method_defined?(method)
+      if @calculations.include?(method)
         magic.perform(relation, method, *args, &block)
-      elsif @relation.respond_to?(method, true)
+      elsif relation.respond_to?(method, true)
         Groupdate::Series.new(magic, relation.send(method, *args, &block))
       else
         super
@@ -20,11 +20,36 @@ module Groupdate
     end
  
     def respond_to?(method, include_all = false)
-      ActiveRecord::Calculations.method_defined?(method) || relation.respond_to?(method) || super
+      @calculations.include?(method) || relation.respond_to?(method) || super
     end
  
     def reverse_order_value
       nil
     end
   end
+
+  class Calculations
+    attr_reader :relation
+
+    def initialize(relation)
+      @relation = relation
+    end
+
+    def include?(method)
+      # https://github.com/rails/rails/blob/master/activerecord/lib/active_record/relation/calculations.rb
+      ActiveRecord::Calculations.method_defined?(method) || custom_calculations.include?(method)
+    end
+
+    def custom_calculations
+      return [] if !model.respond_to?(:groupdate_calculation_methods)
+      model.groupdate_calculation_methods
+    end
+
+    private
+
+    def model
+      return if !relation.respond_to?(:klass)
+      relation.klass
+    end
+  end
 end
@@ -18,6 +18,18 @@ ActiveRecord::Base.time_zone_aware_attributes = true
  
 class User < ActiveRecord::Base
   has_many :posts
+
+  def self.groupdate_calculation_methods
+    [:custom_count, :undefined_calculation]
+  end
+
+  def self.custom_count
+    count
+  end
+
+  def self.unlisted_calculation
+    count
+  end
 end
  
 class Post < ActiveRecord::Base
@@ -346,6 +358,32 @@ module TestDatabase
     assert_raises(ArgumentError) { User.group_by_day.first }
   end
  
+  # custom model calculation methods
+
+  def test_custom_model_calculation_method
+    create_user "2014-05-01", 1
+    create_user "2014-05-01", 2
+    create_user "2014-05-03", 3
+
+    expected = {
+      Date.parse("2014-05-01") => 2,
+      Date.parse("2014-05-02") => 0,
+      Date.parse("2014-05-03") => 1
+    }
+
+    assert_equal expected, User.group_by_day(:created_at).custom_count
+  end
+
+  def test_using_unlisted_calculation_method_returns_new_series_instance
+    assert_instance_of Groupdate::Series, User.group_by_day(:created_at).unlisted_calculation
+  end
+
+  def test_using_listed_but_undefined_custom_calculation_method_raises_error
+    assert_raises(RuntimeError) do
+      User.group_by_day(:created_at).undefined_calculation
+    end
+  end
+
   private
  
   def call_method(method, field, options)
...	...	@@ -5,14 +5,14 @@ module Groupdate
5	5	def initialize(magic, relation)
6	6	@magic = magic
7	7	@relation = relation
	8	+ @calculations = Groupdate::Calculations.new(relation)
8	9	end
9	10
10	11	# clone to prevent modifying original variables
11	12	def method_missing(method, *args, &block)
12		- # https://github.com/rails/rails/blob/master/activerecord/lib/active_record/relation/calculations.rb
13		- if ActiveRecord::Calculations.method_defined?(method)
	13	+ if @calculations.include?(method)
14	14	magic.perform(relation, method, *args, &block)
15		- elsif @relation.respond_to?(method, true)
	15	+ elsif relation.respond_to?(method, true)
16	16	Groupdate::Series.new(magic, relation.send(method, *args, &block))
17	17	else
18	18	super
...	...	@@ -20,11 +20,36 @@ module Groupdate
20	20	end
21	21
22	22	def respond_to?(method, include_all = false)
23		- ActiveRecord::Calculations.method_defined?(method) \|\| relation.respond_to?(method) \|\| super
	23	+ @calculations.include?(method) \|\| relation.respond_to?(method) \|\| super
24	24	end
25	25
26	26	def reverse_order_value
27	27	nil
28	28	end
29	29	end
	30	+
	31	+ class Calculations
	32	+ attr_reader :relation
	33	+
	34	+ def initialize(relation)
	35	+ @relation = relation
	36	+ end
	37	+
	38	+ def include?(method)
	39	+ # https://github.com/rails/rails/blob/master/activerecord/lib/active_record/relation/calculations.rb
	40	+ ActiveRecord::Calculations.method_defined?(method) \|\| custom_calculations.include?(method)
	41	+ end
	42	+
	43	+ def custom_calculations
	44	+ return [] if !model.respond_to?(:groupdate_calculation_methods)
	45	+ model.groupdate_calculation_methods
	46	+ end
	47	+
	48	+ private
	49	+
	50	+ def model
	51	+ return if !relation.respond_to?(:klass)
	52	+ relation.klass
	53	+ end
	54	+ end
30	55	end
...	...
...	...	@@ -18,6 +18,18 @@ ActiveRecord::Base.time_zone_aware_attributes = true
18	18
19	19	class User < ActiveRecord::Base
20	20	has_many :posts
	21	+
	22	+ def self.groupdate_calculation_methods
	23	+ [:custom_count, :undefined_calculation]
	24	+ end
	25	+
	26	+ def self.custom_count
	27	+ count
	28	+ end
	29	+
	30	+ def self.unlisted_calculation
	31	+ count
	32	+ end
21	33	end
22	34
23	35	class Post < ActiveRecord::Base
...	...	@@ -346,6 +358,32 @@ module TestDatabase
346	358	assert_raises(ArgumentError) { User.group_by_day.first }
347	359	end
348	360
	361	+ # custom model calculation methods
	362	+
	363	+ def test_custom_model_calculation_method
	364	+ create_user "2014-05-01", 1
	365	+ create_user "2014-05-01", 2
	366	+ create_user "2014-05-03", 3
	367	+
	368	+ expected = {
	369	+ Date.parse("2014-05-01") => 2,
	370	+ Date.parse("2014-05-02") => 0,
	371	+ Date.parse("2014-05-03") => 1
	372	+ }
	373	+
	374	+ assert_equal expected, User.group_by_day(:created_at).custom_count
	375	+ end
	376	+
	377	+ def test_using_unlisted_calculation_method_returns_new_series_instance
	378	+ assert_instance_of Groupdate::Series, User.group_by_day(:created_at).unlisted_calculation
	379	+ end
	380	+
	381	+ def test_using_listed_but_undefined_custom_calculation_method_raises_error
	382	+ assert_raises(RuntimeError) do
	383	+ User.group_by_day(:created_at).undefined_calculation
	384	+ end
	385	+ end
	386	+
349	387	private
350	388
351	389	def call_method(method, field, options)
...	...