Errata

<h1>Welcome to your first Rails application<h1>
should be
<h1>Welcome to your first Rails application</h1>

<h1>Welcome to your first Rails application<h1>
should be
<h1>Welcome to your first Rails application</h1>

class GreetingController < ApplicationController
def index
@age=8
@table={"headings" => ["addend", "addend", "sum"],
"body" => [[1, 1, 2], [1, 2, 3], [ 1, 3, 4]]
}
end
end

Won't compile: should use single quotes:

class GreetingController < ApplicationController
def index
@age=8
@table={'headings' => ['addend', 'addend', 'sum'],
'body' => [[1, 1, 2], [1, 2, 3], [ 1, 3, 4]]
}
end
end

class GreetingController < ApplicationController
def index
@age=8
@table={"headings" => ["addend", "addend", "sum"],
"body" => [[1, 1, 2], [1, 2, 3], [ 1, 3, 4]]
}
end
end

Won't compile: should use single quotes:

class GreetingController < ApplicationController
def index
@age=8
@table={'headings' => ['addend', 'addend', 'sum'],
'body' => [[1, 1, 2], [1, 2, 3], [ 1, 3, 4]]
}
end
end

type"Person"
should be
type"Photographer"

type"Person"
should be
type"Photographer"

[:state, :State]
should be
[:state, :state]

[:state, :State]
should be
[:state, :state]

Class: Person
should be
Class: Slide

Class: Person
should be
Class: Slide

text fixtures
should be
test fixtures

text fixtures
should be
test fixtures

you can to see
should be
you can see

you can to see
should be
you can see

has_many :line_items, dependent => true
should be
has_many :line_items, :dependent => true

photo.slides.clear
should be
photo.slides.empty?

has_many :line_items, dependent => true
should be
has_many :line_items, :dependent => true

photo.slides.clear
should be
photo.slides.empty?

Redundant text.
"But we're not ready to run the migration until we've created our model objects and
defined the relationships between photos and categories. You can't run the migration
yet, though. There's no model class for photos, and no relationship between Photo and
Category."

Redundant text.
"But we're not ready to run the migration until we've created our model objects and
defined the relationships between photos and categories. You can't run the migration
yet, though. There's no model class for photos, and no relationship between Photo and
Category."

slideshow
should be
slideshow_id

slideshow
should be
slideshow_id

The code examples for move_higher and move_lower are reversed.

you could implement...
should be
You could implement...

The code examples for move_higher and move_lower are reversed.

you could implement...
should be
You could implement...

...to jumpstarts your development.
shoudl be
...to jumpstart your development.

...to jumpstarts your development.
shoudl be
...to jumpstart your development.

rapidly take shape.
should be
rapidly takes shape.

rapidly take shape.
should be
rapidly takes shape.

rendering elements than are used...
should be
rendering elements that are used...

rendering elements than are used...
should be
rendering elements that are used...

it makes the h call look more like its part of the tag.
should be
it makes the h call look more like it's part of the tag.

it makes the h call look more like its part of the tag.
should be
it makes the h call look more like it's part of the tag.

Finally, it assigns a @selected a list of IDs
should be
Finally, it assigns to @selected a list of IDs

Finally, it assigns a @selected a list of IDs
should be
Finally, it assigns to @selected a list of IDs

The 3 sections explaining the code end with colons and not periods. This is misleading
because they are referring to the code above them, not following them.
That is:
"You saw this line before in the photos list template. It loops through each database row
contained in @slideshows (which was set by the controller), assigning each, in turn, to
slideshow:"
should end with a period and not a colon.

Also:
"This div is simply a caption block that displays the name of the slideshow along with
the number of photos it contains:"
should end with a period and not a colon.

And:
"This div shows a little preview of the slideshow by displaying the thumbnails of the
first three photos in the slideshow:"
should end with a period and not a colon.

The 3 sections explaining the code end with colons and not periods. This is misleading
because they are referring to the code above them, not following them.
That is:
"You saw this line before in the photos list template. It loops through each database row
contained in @slideshows (which was set by the controller), assigning each, in turn, to
slideshow:"
should end with a period and not a colon.

Also:
"This div is simply a caption block that displays the name of the slideshow along with
the number of photos it contains:"
should end with a period and not a colon.

And:
"This div shows a little preview of the slideshow by displaying the thumbnails of the
first three photos in the slideshow:"
should end with a period and not a colon.

The line "padding: 0.50em;" is repeated unnecessarily in the listing for
slideshows.css.

The line "padding: 0.50em;" is repeated unnecessarily in the listing for
slideshows.css.

Finally, notice two Ajax related helpers: drop_receiving_element and observe_field.
should be
Finally, notice the Ajax-related helper drop_receiving_element.

Finally, notice two Ajax related helpers: drop_receiving_element and observe_field.
should be
Finally, notice the Ajax-related helper drop_receiving_element.

...plus the Rad Rails IDE.
should be
...plus the RadRails IDE.
(The latter is used in the same sentence and the remainder of Appendix A.)

...plus the Rad Rails IDE.
should be
...plus the RadRails IDE.
(The latter is used in the same sentence and the remainder of Appendix A.)

...update the paths in the all of the configuration files.
should be
...update the paths in all of the configuration files.

During development, it is easiest use Ruby's...
should be
During development, it is easiest to use Ruby's...

...update the paths in the all of the configuration files.
should be
...update the paths in all of the configuration files.

During development, it is easiest use Ruby's...
should be
During development, it is easiest to use Ruby's...

JavaScrpt
should be
JavaScript

JavaScrpt
should be
JavaScript