1 files changed, 17 insertions, 16 deletions

diff --git a/guides/source/association_basics.md b/guides/source/association_basics.md
index a2231c55d7..4f3e8b2cff 100644
--- a/guides/source/association_basics.md
+++ b/guides/source/association_basics.md
@@ -109,7 +109,7 @@ class CreateBooks < ActiveRecord::Migration[5.0]
     end
 
     create_table :books do |t|
-      t.belongs_to :author, index: true
+      t.belongs_to :author
       t.datetime :published_at
       t.timestamps
     end
@@ -140,7 +140,7 @@ class CreateSuppliers < ActiveRecord::Migration[5.0]
     end
 
     create_table :accounts do |t|
-      t.belongs_to :supplier, index: true
+      t.belongs_to :supplier
       t.string :account_number
       t.timestamps
     end
@@ -184,7 +184,7 @@ class CreateAuthors < ActiveRecord::Migration[5.0]
     end
 
     create_table :books do |t|
-      t.belongs_to :author, index: true
+      t.belongs_to :author
       t.datetime :published_at
       t.timestamps
     end
@@ -231,8 +231,8 @@ class CreateAppointments < ActiveRecord::Migration[5.0]
     end
 
     create_table :appointments do |t|
-      t.belongs_to :physician, index: true
-      t.belongs_to :patient, index: true
+      t.belongs_to :physician
+      t.belongs_to :patient
       t.datetime :appointment_date
       t.timestamps
     end
@@ -312,13 +312,13 @@ class CreateAccountHistories < ActiveRecord::Migration[5.0]
     end
 
     create_table :accounts do |t|
-      t.belongs_to :supplier, index: true
+      t.belongs_to :supplier
       t.string :account_number
       t.timestamps
     end
 
     create_table :account_histories do |t|
-      t.belongs_to :account, index: true
+      t.belongs_to :account
       t.integer :credit_rating
       t.timestamps
     end
@@ -358,8 +358,8 @@ class CreateAssembliesAndParts < ActiveRecord::Migration[5.0]
     end
 
     create_table :assemblies_parts, id: false do |t|
-      t.belongs_to :assembly, index: true
-      t.belongs_to :part, index: true
+      t.belongs_to :assembly
+      t.belongs_to :part
     end
   end
 end
@@ -487,7 +487,7 @@ class CreatePictures < ActiveRecord::Migration[5.0]
   def change
     create_table :pictures do |t|
       t.string :name
-      t.references :imageable, polymorphic: true, index: true
+      t.references :imageable, polymorphic: true
       t.timestamps
     end
   end
@@ -517,7 +517,7 @@ In your migrations/schema, you will add a references column to the model itself.
 class CreateEmployees < ActiveRecord::Migration[5.0]
   def change
     create_table :employees do |t|
-      t.references :manager, index: true
+      t.references :manager
       t.timestamps
     end
   end
@@ -868,7 +868,7 @@ While Rails uses intelligent defaults that will work well in most situations, th
 
 ```ruby
 class Book < ApplicationRecord
-  belongs_to :author, dependent: :destroy,
+  belongs_to :author, touch: :books_updated_at,
     counter_cache: true
 end
 ```
@@ -1048,8 +1048,7 @@ There may be times when you wish to customize the query used by `belongs_to`. Su
 
 ```ruby
 class Book < ApplicationRecord
-  belongs_to :author, -> { where active: true },
-                        dependent: :destroy
+  belongs_to :author, -> { where active: true }
 end
 ```
 
@@ -1259,7 +1258,7 @@ Controls what happens to the associated object when its owner is destroyed:
 * `:destroy` causes the associated object to also be destroyed
 * `:delete` causes the associated object to be deleted directly from the database (so callbacks will not execute)
 * `:nullify` causes the foreign key to be set to `NULL`. Callbacks are not executed.
-* `:restrict_with_exception` causes an exception to be raised if there is an associated record
+* `:restrict_with_exception` causes an `ActiveRecord::DeleteRestrictionError` exception to be raised if there is an associated record
 * `:restrict_with_error` causes an error to be added to the owner if there is an associated object
 
 It's necessary not to set or leave `:nullify` option for those associations
@@ -1660,9 +1659,11 @@ Controls what happens to the associated objects when their owner is destroyed:
 * `:destroy` causes all the associated objects to also be destroyed
 * `:delete_all` causes all the associated objects to be deleted directly from the database (so callbacks will not execute)
 * `:nullify` causes the foreign keys to be set to `NULL`. Callbacks are not executed.
-* `:restrict_with_exception` causes an exception to be raised if there are any associated records
+* `:restrict_with_exception` causes an `ActiveRecord::DeleteRestrictionError` exception to be raised if there are any associated records
 * `:restrict_with_error` causes an error to be added to the owner if there are any associated objects
 
+The `:destroy` and `:delete_all` options also affect the semantics of the `collection.delete` and `collection=` methods by causing them to destroy associated objects when they are removed from the collection.
+
 ##### `:foreign_key`
 
 By convention, Rails assumes that the column used to hold the foreign key on the other model is the name of this model with the suffix `_id` added. The `:foreign_key` option lets you set the name of the foreign key directly: