From a933debf35b5f6a077e5aa29d7b7b6557fdc2e1c Mon Sep 17 00:00:00 2001
From: Andrew Kane <acekane1@gmail.com>
Date: Thu, 14 May 2015 03:26:47 -0700
Subject: [PATCH] Added dynamic grouping - #80

---
 CHANGELOG.md                |  5 +++--
 README.md                   | 12 ++++++++++++
 lib/groupdate/enumerable.rb | 10 ++++++++++
 lib/groupdate/scopes.rb     | 10 ++++++++++
 test/enumerable_test.rb     |  2 +-
 test/test_helper.rb         | 24 +++++++++++++++++++++++-
 6 files changed, 59 insertions(+), 4 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index d0772cd..658a853 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,6 +1,7 @@
-## 2.4.1 [unreleased]
+## 2.5.0 [unreleased]
 
-- raise `ArgumentError` if no block given to enumerable
+- Added `group_by_period` method
+- Raise `ArgumentError` if no block given to enumerable
 
 ## 2.4.0
 
diff --git a/README.md b/README.md
index d2cc95d..b5c9e7d 100644
--- a/README.md
+++ b/README.md
@@ -139,6 +139,18 @@ User.group_by_hour_of_day(:created_at, format: "%l %P").count.keys.first # 12 am
 
 Takes a `String`, which is passed to [strftime](http://strfti.me/), or a `Proc`.  You can pass a locale with the `locale` option.
 
+### Dynamic Grouping [master, may change]
+
+```ruby
+User.group_by_period(:day, :created_at).count
+```
+
+Limit groupings with the `permit` option.
+
+```ruby
+User.group_by_period(params[:period], :created_at, permit: %w[day week]).count
+```
+
 ## Arrays and Hashes
 
 ```ruby
diff --git a/lib/groupdate/enumerable.rb b/lib/groupdate/enumerable.rb
index e18b452..50ce111 100644
--- a/lib/groupdate/enumerable.rb
+++ b/lib/groupdate/enumerable.rb
@@ -8,4 +8,14 @@ module Enumerable
       end
     end
   end
+
+  def group_by_period(period, options = {}, &block)
+    # to_sym is unsafe on user input, so convert to strings
+    permitted_periods = ((options[:permit] || Groupdate::FIELDS).map(&:to_sym) & Groupdate::FIELDS).map(&:to_s)
+    if permitted_periods.include?(period.to_s)
+      send("group_by_#{period}", options, &block)
+    else
+      raise ArgumentError, "Unpermitted period"
+    end
+  end
 end
diff --git a/lib/groupdate/scopes.rb b/lib/groupdate/scopes.rb
index 941aea1..cbda9ef 100644
--- a/lib/groupdate/scopes.rb
+++ b/lib/groupdate/scopes.rb
@@ -10,5 +10,15 @@ module Groupdate
         Groupdate::Magic.new(field, options).relation(args[0], self)
       end
     end
+
+    def group_by_period(period, field, options = {})
+      # to_sym is unsafe on user input, so convert to strings
+      permitted_periods = ((options[:permit] || Groupdate::FIELDS).map(&:to_sym) & Groupdate::FIELDS).map(&:to_s)
+      if permitted_periods.include?(period.to_s)
+        send("group_by_#{period}", field, options)
+      else
+        raise ArgumentError, "Unpermitted period"
+      end
+    end
   end
 end
diff --git a/test/enumerable_test.rb b/test/enumerable_test.rb
index 5f4f090..667f91e 100644
--- a/test/enumerable_test.rb
+++ b/test/enumerable_test.rb
@@ -19,6 +19,6 @@ class TestEnumerable < Minitest::Test
   end
 
   def call_method(method, field, options)
-    Hash[User.all.to_a.send(:"group_by_#{method}", options) { |u| u.send(field) }.map { |k, v| [k, v.size] }]
+    Hash[User.all.to_a.group_by_period(method, options) { |u| u.send(field) }.map { |k, v| [k, v.size] }]
   end
 end
diff --git a/test/test_helper.rb b/test/test_helper.rb
index 7618a4e..2f7278b 100644
--- a/test/test_helper.rb
+++ b/test/test_helper.rb
@@ -739,6 +739,28 @@ module TestGroupdate
     assert_equal ({[1, "Sun"] => 1}), User.group(:score).group_by_week(:created_at, format: "%a").count
   end
 
+  # permit
+
+  def test_permit
+    assert_raises(ArgumentError, "Unpermitted period") { User.group_by_period(:day, :created_at, permit: %w[week]).count }
+  end
+
+  def test_permit_symbol_symbols
+    assert_equal ({}), User.group_by_period(:day, :created_at, permit: %i[day]).count
+  end
+
+  def test_permit_string_symbols
+    assert_equal ({}), User.group_by_period("day", :created_at, permit: %i[day]).count
+  end
+
+  def test_permit_symbol_strings
+    assert_equal ({}), User.group_by_period(:day, :created_at, permit: %w[day]).count
+  end
+
+  def test_permit_string_strings
+    assert_equal ({}), User.group_by_period("day", :created_at, permit: %w[day]).count
+  end
+
   # associations
 
   def test_associations
@@ -807,7 +829,7 @@ module TestGroupdate
   end
 
   def call_method(method, field, options)
-    User.send(:"group_by_#{method}", field, options).count
+    User.group_by_period(method, field, options).count
   end
 
   def create_user(created_at, score = 1)
--
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