Permalink
Browse files

migrations guide: fix and edits [ci skip]

  • Loading branch information...
1 parent 538bd36 commit 3baee0982d25e64cab2eeb046369f0fcf9ee2436 @fxn fxn committed Aug 5, 2013
Showing with 9 additions and 7 deletions.
  1. +9 −7 guides/source/migrations.md
@@ -829,8 +829,7 @@ which contains a `Product` model:
Bob goes on vacation.
Alice creates a migration for the `products` table which adds a new column and
-initializes it. She also adds a validation to the `Product` model for the new
-column.
+initializes it:
```ruby
# db/migrate/20100513121110_add_flag_to_product.rb
@@ -845,6 +844,8 @@ class AddFlagToProduct < ActiveRecord::Migration
end
```
+She also adds a validation to the `Product` model for the new column:
+
```ruby
# app/models/product.rb
@@ -853,9 +854,8 @@ class Product < ActiveRecord::Base
end
```
-Alice adds a second migration which adds and initializes another column to the
-`products` table and also adds a validation to the `Product` model for the new
-column.
+Alice adds a second migration which adds another column to the `products`
+table and initializes it:
```ruby
# db/migrate/20100515121110_add_fuzz_to_product.rb
@@ -870,6 +870,8 @@ class AddFuzzToProduct < ActiveRecord::Migration
end
```
+She also adds a validation to the `Product` model for the new column:
+
```ruby
# app/models/product.rb
@@ -903,7 +905,7 @@ A fix for this is to create a local model within the migration. This keeps
Rails from running the validations, so that the migrations run to completion.
When using a local model, it's a good idea to call
-`Product.reset_column_information` to refresh the `ActiveRecord` cache for the
+`Product.reset_column_information` to refresh the Active Record cache for the
`Product` model prior to updating data in the database.
If Alice had done this instead, there would have been no problem:
@@ -956,7 +958,7 @@ other product attributes.
These migrations run just fine, but when Bob comes back from his vacation
and calls `rake db:migrate` to run all the outstanding migrations, he gets a
subtle bug: The descriptions have defaults, and the `fuzz` column is present,
-but `fuzz` is nil on all products.
+but `fuzz` is `nil` on all products.
The solution is again to use `Product.reset_column_information` before
referencing the Product model in a migration, ensuring the Active Record's

0 comments on commit 3baee09

Please sign in to comment.