Use a deliberately-invalid migration version in all doc examples

If we use a real version, at best that'll be an onerous update required
for each release; at worst, it will encourage users to write new
migrations against an older version than they're using.

The other option would be to leave these bare, without any version
specifier. But as that's just a variant spelling of "4.2", it would seem
to raise the same concerns as above.

1 files changed, 19 insertions, 19 deletions

diff --git a/guides/source/active_record_migrations.md b/guides/source/active_record_migrations.md
index 5aa5dc4f60..b9bb051e7e 100644
--- a/guides/source/active_record_migrations.md
+++ b/guides/source/active_record_migrations.md
@@ -35,7 +35,7 @@ history to the latest version. Active Record will also update your
 Here's an example of a migration:
 
 ```ruby
-class CreateProducts < ActiveRecord::Migration
+class CreateProducts < ActiveRecord::Migration[0.0]
   def change
     create_table :products do |t|
       t.string :name
@@ -72,7 +72,7 @@ If you wish for a migration to do something that Active Record doesn't know how
 to reverse, you can use `reversible`:
 
 ```ruby
-class ChangeProductsPrice < ActiveRecord::Migration
+class ChangeProductsPrice < ActiveRecord::Migration[0.0]
   def change
     reversible do |dir|
       change_table :products do |t|
@@ -87,7 +87,7 @@ end
 Alternatively, you can use `up` and `down` instead of `change`:
 
 ```ruby
-class ChangeProductsPrice < ActiveRecord::Migration
+class ChangeProductsPrice < ActiveRecord::Migration[0.0]
   def up
     change_table :products do |t|
       t.change :price, :string
@@ -129,7 +129,7 @@ $ bin/rails generate migration AddPartNumberToProducts
 This will create an empty but appropriately named migration:
 
 ```ruby
-class AddPartNumberToProducts < ActiveRecord::Migration
+class AddPartNumberToProducts < ActiveRecord::Migration[0.0]
   def change
   end
 end
@@ -146,7 +146,7 @@ $ bin/rails generate migration AddPartNumberToProducts part_number:string
 will generate
 
 ```ruby
-class AddPartNumberToProducts < ActiveRecord::Migration
+class AddPartNumberToProducts < ActiveRecord::Migration[0.0]
   def change
     add_column :products, :part_number, :string
   end
@@ -162,7 +162,7 @@ $ bin/rails generate migration AddPartNumberToProducts part_number:string:index
 will generate
 
 ```ruby
-class AddPartNumberToProducts < ActiveRecord::Migration
+class AddPartNumberToProducts < ActiveRecord::Migration[0.0]
   def change
     add_column :products, :part_number, :string
     add_index :products, :part_number
@@ -180,7 +180,7 @@ $ bin/rails generate migration RemovePartNumberFromProducts part_number:string
 generates
 
 ```ruby
-class RemovePartNumberFromProducts < ActiveRecord::Migration
+class RemovePartNumberFromProducts < ActiveRecord::Migration[0.0]
   def change
     remove_column :products, :part_number, :string
   end
@@ -196,7 +196,7 @@ $ bin/rails generate migration AddDetailsToProducts part_number:string price:dec
 generates
 
 ```ruby
-class AddDetailsToProducts < ActiveRecord::Migration
+class AddDetailsToProducts < ActiveRecord::Migration[0.0]
   def change
     add_column :products, :part_number, :string
     add_column :products, :price, :decimal
@@ -215,7 +215,7 @@ $ bin/rails generate migration CreateProducts name:string part_number:string
 generates
 
 ```ruby
-class CreateProducts < ActiveRecord::Migration
+class CreateProducts < ActiveRecord::Migration[0.0]
   def change
     create_table :products do |t|
       t.string :name
@@ -239,7 +239,7 @@ $ bin/rails generate migration AddUserRefToProducts user:references
 generates
 
 ```ruby
-class AddUserRefToProducts < ActiveRecord::Migration
+class AddUserRefToProducts < ActiveRecord::Migration[0.0]
   def change
     add_reference :products, :user, index: true, foreign_key: true
   end
@@ -257,7 +257,7 @@ $ bin/rails g migration CreateJoinTableCustomerProduct customer product
 will produce the following migration:
 
 ```ruby
-class CreateJoinTableCustomerProduct < ActiveRecord::Migration
+class CreateJoinTableCustomerProduct < ActiveRecord::Migration[0.0]
   def change
     create_join_table :customers, :products do |t|
       # t.index [:customer_id, :product_id]
@@ -281,7 +281,7 @@ $ bin/rails generate model Product name:string description:text
 will create a migration that looks like this
 
 ```ruby
-class CreateProducts < ActiveRecord::Migration
+class CreateProducts < ActiveRecord::Migration[0.0]
   def change
     create_table :products do |t|
       t.string :name
@@ -309,7 +309,7 @@ $ bin/rails generate migration AddDetailsToProducts 'price:decimal{5,2}' supplie
 will produce a migration that looks like this
 
 ```ruby
-class AddDetailsToProducts < ActiveRecord::Migration
+class AddDetailsToProducts < ActiveRecord::Migration[0.0]
   def change
     add_column :products, :price, :decimal, precision: 5, scale: 2
     add_reference :products, :supplier, polymorphic: true, index: true
@@ -563,7 +563,7 @@ to reverse. You can use `reversible` to specify what to do when running a
 migration and what else to do when reverting it. For example:
 
 ```ruby
-class ExampleMigration < ActiveRecord::Migration
+class ExampleMigration < ActiveRecord::Migration[0.0]
   def change
     create_table :distributors do |t|
       t.string :zipcode
@@ -616,7 +616,7 @@ is wise to perform the transformations in precisely the reverse order they were
 made in the `up` method. The example in the `reversible` section is equivalent to:
 
 ```ruby
-class ExampleMigration < ActiveRecord::Migration
+class ExampleMigration < ActiveRecord::Migration[0.0]
   def up
     create_table :distributors do |t|
       t.string :zipcode
@@ -659,7 +659,7 @@ You can use Active Record's ability to rollback migrations using the `revert` me
 ```ruby
 require_relative '20121212123456_example_migration'
 
-class FixupExampleMigration < ActiveRecord::Migration
+class FixupExampleMigration < ActiveRecord::Migration[0.0]
   def change
     revert ExampleMigration
 
@@ -677,7 +677,7 @@ is later decided it would be best to use Active Record validations,
 in place of the `CHECK` constraint, to verify the zipcode.
 
 ```ruby
-class DontUseConstraintForZipcodeValidationMigration < ActiveRecord::Migration
+class DontUseConstraintForZipcodeValidationMigration < ActiveRecord::Migration[0.0]
   def change
     revert do
       # copy-pasted code from ExampleMigration
@@ -841,7 +841,7 @@ Several methods are provided in migrations that allow you to control all this:
 For example, this migration:
 
 ```ruby
-class CreateProducts < ActiveRecord::Migration
+class CreateProducts < ActiveRecord::Migration[0.0]
   def change
     suppress_messages do
       create_table :products do |t|
@@ -1015,7 +1015,7 @@ to add or modify data. This is useful in an existing database that can't be dest
 and recreated, such as a production database. 
 
 ```ruby
-class AddInitialProducts < ActiveRecord::Migration
+class AddInitialProducts < ActiveRecord::Migration[0.0]
   def up
     5.times do |i|
       Product.create(name: "Product ##{i}", description: "A product.")