w4d2 - rails

Question 1

What’s the naming convention for controllers?

Answer 1

plural and CamelCase

Question 2

What’s the naming convention for views?

Answer 2

[name of action].html.erb

Question 3

What does erb stand for?

Answer 3

Embedded RuBy

Question 4

What’s the difference between the two erb ruby tags?

Answer 4

The one with the equals will be rendered. The one without will not be rendered.

Question 5

What’s the name of the parent layout?

Answer 5

application.html.erb

Question 6

What are url helper methods? Where are they defined? How do you use them?

Answer 6

Shortcuts for the url that will point to a particular action.

They are defined in routes.rb and can be seen via ‘rails routes’.

You use them as if they are a method, so:

redirect_to whatever_url

Question 7

What causes a DoubleRenderError? What’s one way to get around it?

Answer 7

The cause is assuming that methods like redirect_to and render act like returns, and then using these multiple times in an action.

To get around it, place a return statement after using a conditional redirect_to/render

Question 8

How do you specify which url and which method a form will submit to?

Answer 8

form action=”url” method=”post/get”

For PATCH/PUT:

Use the method above with ‘post’ AND THEN add a hidden input like so:

input type=”hidden” name=”_method” value=”PATCH/PUT”

Question 9

What’s the general pattern for create?

Answer 9

Call new on a model, passing in params.

Try to save it. If it saves, we show user the show view. If it fails, we show the user the create view.

Question 10

When first starting out, how do you allow rails to accept forms without auth tokens?

Answer 10

Comment out the protect_from_forgery line in application_controller.rb

Question 11

How do you render a partial from inside of a view?

Answer 11

render ‘partial_name’, var1: :value1, var2: :value2, …

Question 12

What’s a shortcut to render a partial for each model in a collection?

What needs to be set up for this to work?

Answer 12

render @mymodels

There must be a model named ‘mymodel’ AND there must be a partial named ‘_mymodel’

Question 13

What’s the name of the gem that gives a REPL in the browser with the ‘fail’ keyword?

Answer 13

better_errors

Question 14

What are the 3 places rails params come from?

Answer 14

query params
route URI/wildcards
POST/PATCH request data

Question 15

What are the 5 aspects of a HTTP request?

Answer 15

method
path
query string
header fields
body

Question 16

What do these 5 things add up to?

method
path
query string
header fields
body

Answer 16

a HTTP request

Question 17

What’s the difference between PUT/PATCH?

Answer 17

PUT sends the entire model through, regardless of what changed.

PATCH only sends the changed parts

Question 18

What are the 5 categories of HTTP status codes?

Answer 18

1xx - informational
2xx - success
3xx - redirection
4xx - client errors
5xx - server errors

Question 19

What does the request/response lifecycle of a rails app look like?

Answer 19

browser sends request to server
server receives request
router instantiates correct controller instance
controller receives params, instantiates models
models query database
controller handles logic and renders view
controller returns view back to server
server wraps view in HTTP headers
server hands response to client

Question 20

What does the router do?

Answer 20

Takes in a method/path and instantiates an appropriate controller and invokes an appropriate method

Question 21

What does a simple route look like for tweets?

Assume the presence of a TweetsController.

Answer 21

get ‘/tweets’, to: ‘tweets#index’

Question 22

What are the 4 parts of a route?

Answer 22

method
path
controller
action

Question 23

method
path
controller
action

These combine to form what?

Answer 23

A route

Question 24

How do you use render to show a JSON object?

Answer 24

render :json object

Question 25

What does this do:

render :json object

Answer 25

Renders a JSON object to the client

Question 26

What are the 5 standard RESTful methods and what do they do?

1 star per

Answer 26

index - shows all items
show - shows one item
create - makes a new object
update - changes an existing object
destroy - deletes an object

Question 27

RESTfully, where do we post things in order to create them?

Answer 27

POST /index

Question 28

RESTfully, what’s the proper create method look like?

Answer 28

1. Create a new model instance based on POST params.
2. if we can save this model, render/redirect to success page
   else: render an error

Question 29

What are weak parameters? How does rails guard against it? What is it called?

Answer 29

You can’t create a new model like this:

Thing.new(params)

You have to use

params.require(:thing).permit(:attribute1, :attribute2, …)

This is called strong parameters

Question 30

What is the :id part of /index/:id called?

Answer 30

wildcard

Question 31

What’s the shortcut for creating RESTful routes?

Answer 31

in routes.rb:

resources :plural_model

Question 32

How do you update multiple attribute for a model at once?

Answer 32

model.update_attributes(params)

Question 33

why or why shouldn’t you use instance vars in partials

Answer 33

you can, but you shouldn’t.

Failing to provide a required instance variable can produce confusing errors, rather than the unambiguous”no local variable defined”error raised when a local variable is undefined.