After automatically updating Postgres to 10.0 via Homebrew, the pg_ctl start command didn't work. | |
The error was "The data directory was initialized by PostgreSQL version 9.6, which is not compatible with this version 10.0." | |
Database files have to be updated before starting the server, here are the steps that had to be followed: | |
# need to have both 9.6.x and latest 10.0 installed, and keep 10.0 as default | |
brew unlink postgresql | |
brew install postgresql@9.6 | |
brew unlink postgresql@9.6 | |
brew link postgresql |
PART 2 | PART 3 | PART 4 | NOTES | SHARE YOUR PROJECT
This is an implementation of a scale exercise widely used in jazz teaching. It's sometimes known as the "big scale" exercise.
Let's say you practice the saxophone and you want to make sure you know all your major scales. One way to test this would be to play the scale within the limits of your instrument - saxophones have a lowest note and a highest note (from :Db3 to :A5 at concert pitch in Sonic-Pi speak - see here http://en.wikipedia.org/wiki/Alto_saxophone#Range - assuming you don't get fancy with harmonics!)
Playing an Eb major scale over the whole range of the instrument would mean playing from :D3 to Ab5 (concert) as the lowest and highest notes available don't appear in the scale (:Db3 and :A5 respectively). When you hit the upper or lower limit you just reverse the direction and carry on going.
Look at the following image...
...it shows an object being tested.
You can't see inside the object. All you can do is send it messages. This is an important point to make because we should be "testing the interface, and NOT the implementation" - doing so will allow us to change the implementation without causing our tests to break.
#Model | |
@user.should have(1).error_on(:username) # Checks whether there is an error in username | |
@user.errors[:username].should include("can't be blank") # check for the error message | |
#Rendering | |
response.should render_template(:index) | |
#Redirecting | |
response.should redirect_to(movies_path) |
The normal controller/view flow is to display a view template corresponding to the current controller action, but sometimes we want to change that. We use render
in a controller when we want to respond within the current request, and redirect_to
when we want to spawn a new request.
The render
method is very overloaded in Rails. Most developers encounter it within the view template, using render :partial => 'form'
or render @post.comments
, but here we'll focus on usage within the controller.
=Navigating= | |
visit('/projects') | |
visit(post_comments_path(post)) | |
=Clicking links and buttons= | |
click_link('id-of-link') | |
click_link('Link Text') | |
click_button('Save') | |
click('Link Text') # Click either a link or a button | |
click('Button Value') |