Fix Active Record validation error messages markup in guides

The other way it was not marking the text as italic, it was showing the
underlines as normal text.

Also fixes some code examples indentation and # => marks in Active Model
and Active Record guides.

[ci skip]

guides/source/active_model_basics.md

@@ -85,9 +85,9 @@ class Person
 end
 
 person = Person.new
-person.to_model == person  #=> true
-person.to_key              #=> nil
-person.to_param            #=> nil
+person.to_model == person  # => true
+person.to_key              # => nil
+person.to_param            # => nil
 ```
 
 ### Dirty
@@ -130,22 +130,22 @@ end
 
 ```ruby
 person = Person.new
-person.changed? #=> false
+person.changed? # => false
 
 person.first_name = "First Name"
-person.first_name #=> "First Name"
+person.first_name # => "First Name"
 
 # returns if any attribute has changed.
-person.changed? #=> true
+person.changed? # => true
 
 # returns a list of attributes that have changed before saving.
-person.changed #=> ["first_name"]
+person.changed # => ["first_name"]
 
 # returns a hash of the attributes that have changed with their original values.
-person.changed_attributes #=> {"first_name"=>nil}
+person.changed_attributes # => {"first_name"=>nil}
 
 # returns a hash of changes, with the attribute names as the keys, and the values will be an array of the old and new value for that field.
-person.changes #=> {"first_name"=>[nil, "First Name"]}
+person.changes # => {"first_name"=>[nil, "First Name"]}
 ```
 
 #### Attribute based accessor methods
@@ -154,23 +154,23 @@ Track whether the particular attribute has been changed or not.
 
 ```ruby
 # attr_name_changed?
-person.first_name #=> "First Name"
-person.first_name_changed? #=> true
+person.first_name # => "First Name"
+person.first_name_changed? # => true
 ```
 
 Track what was the previous value of the attribute.
 
 ```ruby
 # attr_name_was accessor
-person.first_name_was  #=> "First Name"
+person.first_name_was # => "First Name"
 ```
 
 Track both previous and current value of the changed attribute. Returns an array if changed, else returns nil.
 
 ```ruby
 # attr_name_change
-person.first_name_change #=> [nil, "First Name"]
-person.last_name_change #=> nil
+person.first_name_change # => [nil, "First Name"]
+person.last_name_change # => nil
 ```
 
 ### Validations
@@ -189,12 +189,12 @@ class Person
 end
 
 person = Person.new(token: "2b1f325")
-person.valid?                        #=> false
+person.valid?                        # => false
 person.name = 'vishnu'
 person.email = 'me'
-person.valid?                        #=> false
+person.valid?                        # => false
 person.email = 'me@vishnuatrai.com'
-person.valid?                        #=> true
+person.valid?                        # => true
 person.token = nil
-person.valid?                        #=> raises ActiveModel::StrictValidationFailed
+person.valid?                        # => raises ActiveModel::StrictValidationFailed
 ```

guides/source/active_record_basics.md

@@ -147,50 +147,50 @@ Active Record objects can be created from a hash, a block or have their attribut
 For example, given a model `User` with attributes of `name` and `occupation`, the `create` method call will create and save a new record into the database:
 
 ```ruby
-  user = User.create(name: "David", occupation: "Code Artist")
+user = User.create(name: "David", occupation: "Code Artist")
 ```
 
 Using the `new` method, an object can be created without being saved:
 
 ```ruby
-  user = User.new
-  user.name = "David"
-  user.occupation = "Code Artist"
+user = User.new
+user.name = "David"
+user.occupation = "Code Artist"
 ```
 
 A call to `user.save` will commit the record to the database.
 
 Finally, if a block is provided, both `create` and `new` will yield the new object to that block for initialization:
 
 ```ruby
-  user = User.new do |u|
-    u.name = "David"
-    u.occupation = "Code Artist"
-  end
+user = User.new do |u|
+  u.name = "David"
+  u.occupation = "Code Artist"
+end
 ```
 
 ### Read
 
 Active Record provides a rich API for accessing data within a database. Below are a few examples of different data access methods provided by Active Record.
 
 ```ruby
-  # return array with all records
-  users = User.all
+# return array with all records
+users = User.all
 ```
 
 ```ruby
-  # return the first record
-  user = User.first
+# return the first record
+user = User.first
 ```
 
 ```ruby
-  # return the first user named David
-  david = User.find_by_name('David')
+# return the first user named David
+david = User.find_by_name('David')
 ```
 
 ```ruby
-  # find all users named David who are Code Artists and sort by created_at in reverse chronological order
-  users = User.where(name: 'David', occupation: 'Code Artist').order('created_at DESC')
+# find all users named David who are Code Artists and sort by created_at in reverse chronological order
+users = User.where(name: 'David', occupation: 'Code Artist').order('created_at DESC')
 ```
 
 You can learn more about querying an Active Record model in the [Active Record Query Interface](active_record_querying.html) guide.
@@ -200,18 +200,18 @@ You can learn more about querying an Active Record model in the [Active Record Q
 Once an Active Record object has been retrieved, its attributes can be modified and it can be saved to the database.
 
 ```ruby
-  user = User.find_by_name('David')
-  user.name = 'Dave'
-  user.save
+user = User.find_by_name('David')
+user.name = 'Dave'
+user.save
 ```
 
 ### Delete
 
 Likewise, once retrieved an Active Record object can be destroyed which removes it from the database.
 
 ```ruby
-  user = User.find_by_name('David')
-  user.destroy
+user = User.find_by_name('David')
+user.destroy
 ```
 
 Validations

guides/source/active_record_callbacks.md

@@ -200,7 +200,7 @@ Halting Execution
 
 As you start registering new callbacks for your models, they will be queued for execution. This queue will include all your model's validations, the registered callbacks, and the database operation to be executed.
 
-The whole callback chain is wrapped in a transaction. If any <em>before</em> callback method returns exactly `false` or raises an exception, the execution chain gets halted and a ROLLBACK is issued; <em>after</em> callbacks can only accomplish that by raising an exception.
+The whole callback chain is wrapped in a transaction. If any _before_ callback method returns exactly `false` or raises an exception, the execution chain gets halted and a ROLLBACK is issued; _after_ callbacks can only accomplish that by raising an exception.
 
 WARNING. Raising an arbitrary exception may break code that expects `save` and its friends not to fail like that. The `ActiveRecord::Rollback` exception is thought precisely to tell Active Record a rollback is going on. That one is internally captured but not reraised.
 

guides/source/active_record_validations.md

@@ -264,7 +264,7 @@ class Person < ActiveRecord::Base
 end
 ```
 
-The default error message for this helper is "_must be accepted_".
+The default error message for this helper is _"must be accepted"_.
 
 It can receive an `:accept` option, which determines the value that will be
 considered acceptance. It defaults to "1" and can be easily changed.
@@ -293,7 +293,7 @@ This validation will work with all of the association types.
 CAUTION: Don't use `validates_associated` on both ends of your associations.
 They would call each other in an infinite loop.
 
-The default error message for `validates_associated` is "_is invalid_". Note
+The default error message for `validates_associated` is _"is invalid"_. Note
 that each associated object will contain its own `errors` collection; errors do
 not bubble up to the calling model.
 
@@ -328,7 +328,7 @@ class Person < ActiveRecord::Base
 end
 ```
 
-The default error message for this helper is "_doesn't match confirmation_".
+The default error message for this helper is _"doesn't match confirmation"_.
 
 ### `exclusion`
 
@@ -348,7 +348,7 @@ alias called `:within` that you can use for the same purpose, if you'd like to.
 This example uses the `:message` option to show how you can include the
 attribute's value.
 
-The default error message is "_is reserved_".
+The default error message is _"is reserved"_.
 
 ### `format`
 
@@ -362,7 +362,7 @@ class Product < ActiveRecord::Base
 end
 ```
 
-The default error message is "_is invalid_".
+The default error message is _"is invalid"_.
 
 ### `inclusion`
 
@@ -381,7 +381,7 @@ will be accepted. The `:in` option has an alias called `:within` that you can
 use for the same purpose, if you'd like to. The previous example uses the
 `:message` option to show how you can include the attribute's value.
 
-The default error message for this helper is "_is not included in the list_".
+The default error message for this helper is _"is not included in the list"_.
 
 ### `length`
 
@@ -471,24 +471,24 @@ Besides `:only_integer`, this helper also accepts the following options to add
 constraints to acceptable values:
 
 * `:greater_than` - Specifies the value must be greater than the supplied
-  value. The default error message for this option is "_must be greater than
-  %{count}_".
+  value. The default error message for this option is _"must be greater than
+  %{count}"_.
 * `:greater_than_or_equal_to` - Specifies the value must be greater than or
   equal to the supplied value. The default error message for this option is
-  "_must be greater than or equal to %{count}_".
+  _"must be greater than or equal to %{count}"_.
 * `:equal_to` - Specifies the value must be equal to the supplied value. The
-  default error message for this option is "_must be equal to %{count}_".
+  default error message for this option is _"must be equal to %{count}"_.
 * `:less_than` - Specifies the value must be less than the supplied value. The
-  default error message for this option is "_must be less than %{count}_".
+  default error message for this option is _"must be less than %{count}"_.
 * `:less_than_or_equal_to` - Specifies the value must be less than or equal the
-  supplied value. The default error message for this option is "_must be less
-  than or equal to %{count}_".
+  supplied value. The default error message for this option is _"must be less
+  than or equal to %{count}"_.
 * `:odd` - Specifies the value must be an odd number if set to true. The
-  default error message for this option is "_must be odd_".
+  default error message for this option is _"must be odd"_.
 * `:even` - Specifies the value must be an even number if set to true. The
-  default error message for this option is "_must be even_".
+  default error message for this option is _"must be even"_.
 
-The default error message is "_is not a number_".
+The default error message is _"is not a number"_.
 
 ### `presence`
 
@@ -528,7 +528,7 @@ If you validate the presence of an object associated via a `has_one` or
 Since `false.blank?` is true, if you want to validate the presence of a boolean
 field you should use `validates :field_name, inclusion: { in: [true, false] }`.
 
-The default error message is "_can't be empty_".
+The default error message is _"can't be empty"_.
 
 ### `uniqueness`
 
@@ -570,7 +570,7 @@ end
 WARNING. Note that some databases are configured to perform case-insensitive
 searches anyway.
 
-The default error message is "_has already been taken_".
+The default error message is _"has already been taken"_.
 
 ### `validates_with`
 
@@ -714,7 +714,7 @@ class Person < ActiveRecord::Base
   validates :name, presence: { strict: true }
 end
 
-Person.new.valid?  #=> ActiveModel::StrictValidationFailed: Name can't be blank
+Person.new.valid?  # => ActiveModel::StrictValidationFailed: Name can't be blank
 ```
 
 There is also an ability to pass custom exception to `:strict` option
@@ -724,7 +724,7 @@ class Person < ActiveRecord::Base
   validates :token, presence: true, uniqueness: true, strict: TokenGenerationException
 end
 
-Person.new.valid?  #=> TokenGenerationException: Token can't be blank
+Person.new.valid?  # => TokenGenerationException: Token can't be blank
 ```
 
 Conditional Validation
@@ -917,7 +917,7 @@ validations fail.
 
 Because every application handles this kind of thing differently, Rails does
 not include any view helpers to help you generate these messages directly.
-However, due to the rich number of methods Rails gives you to interact with 
+However, due to the rich number of methods Rails gives you to interact with
 validations in general, it's fairly easy to build your own. In addition, when
 generating a scaffold, Rails will put some ERB into the `_form.html.erb` that
 it generates that displays the full list of errors on that model.