1 files changed, 42 insertions, 20 deletions
diff --git a/guides/source/active_record_querying.md b/guides/source/active_record_querying.md
index 63658e7c8b..9d349691b4 100644
--- a/guides/source/active_record_querying.md
+++ b/guides/source/active_record_querying.md
@@ -11,7 +11,7 @@ After reading this guide, you will know:
 * How to specify the order, retrieved attributes, grouping, and other properties of the found records.
 * How to use eager loading to reduce the number of database queries needed for data retrieval.
 * How to use dynamic finder methods.
-* How to use method chaining to use multiple ActiveRecord methods together.
+* How to use method chaining to use multiple Active Record methods together.
 * How to check for the existence of particular records.
 * How to perform various calculations on Active Record models.
 * How to run EXPLAIN on relations.
@@ -153,9 +153,9 @@ You can pass in a numerical argument to the `take` method to return up to that n
 ```ruby
 client = Client.take(2)
 # => [
-  #<Client id: 1, first_name: "Lifo">,
-  #<Client id: 220, first_name: "Sara">
-]
+#   #<Client id: 1, first_name: "Lifo">,
+#   #<Client id: 220, first_name: "Sara">
+# ]
 ```
 
 The SQL equivalent of the above is:
@@ -192,10 +192,10 @@ You can pass in a numerical argument to the `first` method to return up to that
 ```ruby
 client = Client.first(3)
 # => [
-  #<Client id: 1, first_name: "Lifo">,
-  #<Client id: 2, first_name: "Fifo">,
-  #<Client id: 3, first_name: "Filo">
-]
+#   #<Client id: 1, first_name: "Lifo">,
+#   #<Client id: 2, first_name: "Fifo">,
+#   #<Client id: 3, first_name: "Filo">
+# ]
 ```
 
 The SQL equivalent of the above is:
@@ -243,10 +243,10 @@ You can pass in a numerical argument to the `last` method to return up to that n
 ```ruby
 client = Client.last(3)
 # => [
-  #<Client id: 219, first_name: "James">,
-  #<Client id: 220, first_name: "Sara">,
-  #<Client id: 221, first_name: "Russel">
-]
+#   #<Client id: 219, first_name: "James">,
+#   #<Client id: 220, first_name: "Sara">,
+#   #<Client id: 221, first_name: "Russel">
+# ]
 ```
 
 The SQL equivalent of the above is:
@@ -1296,6 +1296,28 @@ Using a class method is the preferred way to accept arguments for scopes. These
 category.articles.created_before(time)
 ```
 
+### Using conditionals
+
+Your scope can utilize conditionals:
+
+```ruby
+class Article < ApplicationRecord
+  scope :created_before, ->(time) { where("created_at < ?", time) if time.present? }
+end
+```
+
+Like the other examples, this will behave similarly to a class method.
+
+```ruby
+class Article < ApplicationRecord
+  def self.created_before(time)
+    where("created_at < ?", time) if time.present?
+  end
+end
+```
+
+However, there is one important caveat: A scope will always return an `ActiveRecord::Relation` object, even if the conditional evaluates to `false`, whereas a class method, will return `nil`. This can cause `NoMethodError` when chaining class methods with conditionals, if any of the conditionals return `false`.
+
 ### Applying a default scope
 
 If we wish for a scope to be applied across all queries to the model we can use the
@@ -1591,7 +1613,7 @@ now want the client named 'Nick':
 
 ```ruby
 nick = Client.find_or_initialize_by(first_name: 'Nick')
-# => <Client id: nil, first_name: "Nick", orders_count: 0, locked: true, created_at: "2011-08-30 06:09:27", updated_at: "2011-08-30 06:09:27">
+# => #<Client id: nil, first_name: "Nick", orders_count: 0, locked: true, created_at: "2011-08-30 06:09:27", updated_at: "2011-08-30 06:09:27">
 
 nick.persisted?
 # => false
@@ -1623,10 +1645,10 @@ Client.find_by_sql("SELECT * FROM clients
   INNER JOIN orders ON clients.id = orders.client_id
   ORDER BY clients.created_at desc")
 # =>  [
-  #<Client id: 1, first_name: "Lucas" >,
-  #<Client id: 2, first_name: "Jan" >,
-  # ...
-]
+#   #<Client id: 1, first_name: "Lucas" >,
+#   #<Client id: 2, first_name: "Jan" >,
+#   ...
+# ]
 ```
 
 `find_by_sql` provides you with a simple way of making custom calls to the database and retrieving instantiated objects.
@@ -1638,9 +1660,9 @@ Client.find_by_sql("SELECT * FROM clients
 ```ruby
 Client.connection.select_all("SELECT first_name, created_at FROM clients WHERE id = '1'")
 # => [
-  {"first_name"=>"Rafael", "created_at"=>"2012-11-10 23:23:45.281189"},
-  {"first_name"=>"Eileen", "created_at"=>"2013-12-09 11:22:35.221282"}
-]
+#   {"first_name"=>"Rafael", "created_at"=>"2012-11-10 23:23:45.281189"},
+#   {"first_name"=>"Eileen", "created_at"=>"2013-12-09 11:22:35.221282"}
+# ]
 ```
 
 ### `pluck`