Rails Controllers

Question 1

controller index (without views)

Answer 1

def index
books = Book.all
render json: books
end

Question 2

controller show (without views)

Answer 2

def show
book = Book.find_by(id: [params[:id])
render json: book
end

Question 3

How do you check what routes are available?

Answer 3

bundle exec rake routes

Question 4

What do I do when I want something to be the VIEW of an index controller action?

Answer 4

app/views/books/index.html.erb

its going to be an html file, and erb is embedded ruby code.

Question 5

controller index (with views)

Answer 5

def index
@books = Books.all #this allows me to call the @books instance variable. we can do this b/c of erb.
render ‘index’ #this renders a template
end

Question 6

How do we write ruby code that not be printed in the erb?

Answer 6

shortcut in atom: - tab

Question 7

How do we write ruby code that will be printed in the erb?

Answer 7

shortcut in atom: = tab

Question 8

How to show each book in <ul> in erb?</ul>

Answer 8

<ul>

<li>

</ul>
</li></ul>

Question 9

controller show (with views)

Answer 9

def show
@book = Book.find_by(:id, params[:id]) #because we want to access it in the html.erb
render :show
end

Question 10

What do I do when I want something to be the VIEW of an SHOW controller action?

Answer 10

show.html.erb

Question 11

What if we don’t find the book we are trying to show?

Answer 11

def show
@book = Book.find_by(:id, params[:id]) #because we want to access it in the html.erb
if @book
render :show #packages up our response and give back to the cleint
else
render :index
redirect_to ‘/books’ #its in our routes!
#hey, make a new request.
end

end

Question 12

How many redirects can we have in a method?

Answer 12

One. Redirect does not end execution of your meothd. Might get a double render error.

Question 13

What does a template missing error mean?

Answer 13

We were able to find this controller action, but we couldn’t find a template.

Question 14

New in views?

Answer 14

def new
render :new
end

Question 15

new.html.erb

Answer 15

<h1> Add book to Library! </h1>

form action=”/books” method=”post”>
Title

Question 16

new.html.erb and user’s info gets into the ??

Answer 16

<h1> Add book to Library! </h1>

form action=”/books” method=”post”>
Title

Question 17

Example of a params hash-like object?

Answer 17

{“title” => “Harry Potter”, “controller” => “books”, “action”=>”create”}

Question 18

Convention in terminal for generating a migration?

Answer 18

rails generate migration CreateTableName

Question 19

When you create a model, is it plural or singular?

Answer 19

User (singular)

Question 20

Inside a form, how do you create labels?

Answer 20

Title

Author

Year

Question 21

in schema,

t.string “category”

Answer 21

Lets us choose stuff easier

Question 22

We want of what to be inside a key of book?

Answer 22

our params! {“title” => “Harry Potter”, “controller” => “books”, “action”=>”create”}

we don’t have to fish out, we can just say params[:book] in html.

Question 23

How do we nest our params variable inside our label html tags?

Answer 23

Title

Author

Year

Question 24

How do we add category, drop down?

Answer 24

Fiction!

Question 25

How do we add category, drop down without a default?

Answer 25

–Please select–
Fiction!
Fiction!

Question 26

How do we give them more space to write a description?

Answer 26

Description

Question 27

How can we add break lines in our new.html.erb?

Answer 27

<br></br><br></br>

Question 28

How do we add a label?

Answer 28

Description

Question 29

How do i get a nice calendar drop down?

Answer 29

instead of:

Question 30

How do we get our data to persist?

Answer 30

We need an action and a method.

We nested the params data under the key of book name=”book[title]” (through the name attributeo n the html page itself)

this lets our data persist!

Question 31

How do we CREATE an instance of a book?

Answer 31

@book (instance variables are accessible in the views.)

Question 32

What do we want to pass into our new instance of book?

Answer 32

params!
def create
@book = Book.new(params[:book])
end

Question 33

If we can’t save the new book, where do we want to send the user?

Answer 33

back to the form.

Question 34

How do we send the user back to the form in case of an error?

Answer 34

def create
  @book = Book.new(params[:book])
  if @book.save
     redirect_to book_url(@book) #it extracts the id for us
else 
     render :new
end

Question 35

What if our user added new fields to our params?
How do we use strong params?
To only allow the user to only use the fields we want?

Answer 35

def create 
  @book = Book.new(book_params)

##if @book.save, redirect_to book_url(@book) else render:new end##
end 

private
def book_params (convention is to take name of the model and append it to params)
params.require(:book).permit(:title, :author, :year, :description, :category)

Question 36

What happens if we try to pass our book directly into Book.new ?

Answer 36

rails throws an error.

Question 37

protect_from_forgery with: exception

Answer 37

this is commented out just now only because we haven’t learned auth.

Question 38

What happens if you go to localhost:3000/book/new?

Answer 38

its not
localhost:3000/books/new

so you get a routing error.

Question 39

What should you think if you get a routing error?

Answer 39

1. What route was I trying to go to?
2. What route did I go to?
3. Why did I go to this route?

Question 40

How do I begin to see

1. What route was I trying to go to?

Answer 40

go to bundle exec rake routes

and see what routes are available.

Now run the rake routes table.

Question 41

If you don’t know where to go, go to…

Answer 41

The rails server logs. that’s where we see what rails tried to do with that information.

Question 42

What is Book Load in server logs?

Answer 42

Our SQL query! if its returning the wrong information, then we can see what’s actually being run in SQL.

Question 43

What’s are two good gems to debug our controller?

Answer 43

gem ‘better_errors’ #better stack trace

gem ‘binding_of_caller’ #opens an interactive repl before our code crashes. WOW! sandbox environment.

Question 44

Don’t forget to ____ after you bundle install better_errors and binding_of_caller)

Answer 44

restart the console!

rails c

Question 45

What keyword do we need to use to hit our stack trace?

Answer 45

We want to use keyword

fail

to get binding_of_caller and better_errors to work.

Question 46

@book.errors.full_messages

[“Year cannot be in the future”]

Answer 46

These error messages come from the model.

Whats going wrong in our model?
We can use byebug! (But DON’T require byebug at the top, its default installed in your gemfile.)

Question 47

If you don’t c

out of byebug, what will happen?

Answer 47

You will not be able to make new requests, you will be hung in this byebug.

Question 48

When I see COMMIT, what do I know?

Answer 48

I know the data persisted to the database.

Question 49

302?

Answer 49

redirect to the show page.

Question 50

Where do we put gem
‘better_errors’
gem ‘binding_of_caller’

in the gemfile
?

Answer 50

in the group: development!

that way they will only be used in production.
we don’t want hackers to see our database!