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About the tutorial
17 Mar 15:45, 2020
18 Nov 02:13, 2020
Exercise Answers
Exercise Question:
Confirm that GitHub renders the Markdown for the README in Listing 3.3 as HTML (Figure 3.2).
mokubo's Answer:
Confirmed
Exercise Question:
By visiting the root route on the production server, verify that the deployment to Heroku succeeded.
mokubo's Answer:
200
Exercise Question:
Assign variables
city and state to your current city and state of residence. (If residing outside the U.S., substitute the analogous quantities.)
mokubo's Answer:
$ irb
>> city = "San Francisco"
=> "San Francisco"
>> states = "California"
=> "California"
>> puts "#{city}, #{states}"
San Francisco, California
=> nil
>>
Exercise Question:
Using interpolation, print (using
puts) a string consisting of the city and state separated by a comma and a space, as in “Los Angeles, CA”.
mokubo's Answer:
$ irb
>> city = "San Francisco"
=> "San Francisco"
>> states = "California"
=> "California"
>> puts "#{city}, #{states}"
San Francisco, California
=> nil
>>
Exercise Question:
Repeat the previous exercise but with the city and state separated by a tab character.
mokubo's Answer:
>> puts "#{city}\t#{states}"
San Francisco California
=> nil
>>
Exercise Question:
What is the result if you replace double quotes with single quotes in the previous exercise?
mokubo's Answer:
Printed nothing
>> puts ""#{city}\t#{states}""
=> nil
>>
Exercise Question:
What is the length of the string “racecar”?
mokubo's Answer:
>> "racecar".length
=> 7
>>
Exercise Question:
Confirm using the
reverse method that the string in the previous exercise is the same when its letters are reversed.
mokubo's Answer:
>> "racecar".reverse
=> "racecar"
>>
Exercise Question:
Assign the string “racecar” to the variable
s. Confirm using the comparison operator == that s and s.reverse are equal.
mokubo's Answer:
>> s = "racecar"
=> "racecar"
>> s == s.reverse
=> true
>>
Exercise Question:
What is the result of running the code shown in Listing 4.9? How does it change if you reassign the variable
s to the string “onomatopoeia”? Hint: Use up-arrow to retrieve and edit previous commands
mokubo's Answer:
>> s = "onomatopoeia"
=> "onomatopoeia"
>> s == s.reverse
=> false
>>
Exercise Question:
In the console, confirm that you can use interpolation (Section 4.2.1) to interpolate a raw symbol. For example, what is the return value of
"#{:success}"?
mokubo's Answer:
>> flash.each do |key, value|
?> puts "#{:success}"
>> end
success
success
=> {:success=>"It worked!", :danger=>"It faild!"}
>>
OR
>> puts "#{:success}"
success
=> nil
>>
Exercise Question:
How does the previous exercise relate to the flash iteration shown in Listing 7.28?
mokubo's Answer:
It shows prints value in message types and changes it.
Exercise Question:
According to the default Rails page, what is the version of Ruby on your system? Confirm by running
ruby -v at the command line.
mokubo's Answer:
$ ruby -v
ruby 2.6.6p146 (2020-03-31 revision 67876) [x86_64-darwin19]
$
Exercise Question:
What is the version of Rails? Confirm that it matches the version installed in Listing 1.2.
mokubo's Answer:
$ rails -v
Rails 6.0.3.4
Exercise Question:
Change the content of the
hello action in Listing 1.13 to read “hola, mundo!” instead of “hello, world!”.
mokubo's Answer:
class ApplicationController < ActionController::Base
def hello
render html: "hola, mundo!"
end
end
Exercise Question:
Show that Rails supports non-ASCII characters by including an inverted exclamation point, as in “¡Hola, mundo!” (Figure 1.21).15 To get a ¡ character on a Mac, you can use Option-1; otherwise, you can always copy-and-paste the character into your editor.
mokubo's Answer:
class ApplicationController < ActionController::Base
def hello
render html: "¡hola, mundo!"
end
end
Exercise Question:
By following the example of the
hello action in Listing 1.13, add a second action called goodbye that renders the text “goodbye, world!”. Edit the routes file from Listing 1.15 so that the root route goes to goodbye instead of to hello (Figure 1.22).
mokubo's Answer:
class ApplicationController < ActionController::Base
def hello
render html: "hola, mundo!"
end
def goodbye
render html: "goodbye, world!"
end
end
Exercise Question:
Run
heroku help to see a list of Heroku commands. (If the output of heroku help doesn’t fit in your terminal window, either scroll up or use heroku help | less to pipe to the less command.) What is the command to display logs for an app?
mokubo's Answer:
heroku logs
CLI to interact with Heroku
VERSION
heroku/7.47.1 darwin-x64 node-v12.16.2
USAGE
$ heroku [COMMAND]
COMMANDS
access manage user access to apps
addons tools and services for developing, extending, and operating
your app
apps manage apps on Heroku
auth check 2fa status
authorizations OAuth authorizations
autocomplete display autocomplete installation instructions
buildpacks scripts used to compile apps
certs a topic for the ssl plugin
ci run an application test suite on Heroku
clients OAuth clients on the platform
config environment variables of apps
container Use containers to build and deploy Heroku apps
domains custom domains for apps
drains forward logs to syslog or HTTPS
features add/remove app features
git manage local git repository for app
help display help for heroku
keys add/remove account ssh keys
labs add/remove experimental features
local run Heroku app locally
logs display recent log output
maintenance enable/disable access to app
members manage organization members
notifications display notifications
orgs manage organizations
pg manage postgresql databases
pipelines manage pipelines
plugins list installed plugins
ps Client tools for Heroku Exec
psql open a psql shell to the database
redis manage heroku redis instances
regions list available regions for deployment
releases display the releases for an app
reviewapps manage reviewapps in pipelines
run run a one-off process inside a Heroku dyno
sessions OAuth sessions
spaces manage heroku private spaces
status status of the Heroku platform
teams manage teams
update update the Heroku CLI
webhooks list webhooks on an app
Exercise Question:
It’s well-known that no web page is complete without a cat image. Using the command in Listing 5.4, arrange to download the kitten pic shown in Figure 5.3.11
mokubo's Answer:
$ curl -OL https://cdn.learnenough.com/kitten.jpg
Exercise Question:
In the console, set
user to the first user in the database, and verify by calling it directly that the remember method works. How do remember_token and remember_digest compare?
mokubo's Answer:
hi
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