REST, Representational State Transfer
Learning Goals
- Explain CRUD in the context of web applications.
- Explain what is REST
- Be able to distinguish between a RESTful vs non-RESTful route.
Vocabulary
- CRUD
- REST
- HTTP Verbs
- URI
Review: CRUD
- C - Create
- R - Read
- U - Update
- D - Delete
This is a list of the operations we can perform on a resource.
What is a resource?
- “A conceptual object that has identity, state, and behavior. “
- Generic term for something that we have in our application (e.g. tasks, people, movies)
- Can also refer to files, web pages, sessions, search results, anything on the web.
- Often corresponds to a database table (but not always!)
- The nouns of an application (tweets, users, friends, posts, etc.)
Often, our applications will have a separate controller and model for each resource.
What is REST?
- Representational State Transfer (ReST) is a style of web architecture
- Roy Fielding, doctoral dissertation in 2000
- Seeks to give every web resource a URI (Uniform Resource Identifier) that can be manipulated, and let the software determine what to do from there.
In other words…
- A pattern for combining HTTP verbs, URIs, and the actions they correspond to in order to access (CRUD) resources
- In a Rails app, in which file would you find this information?
- config/routes.rb
- For our purposes, these are guidelines for how we build our routes
HTTP Verbs
Part of an HTTP Request that indicates a type of action to perform on a resource.
- GET: retrieve a resource
- POST: create a new resource
- PUT: update an entire existing resource
- PATCH: update part of an existing resource
- DELETE: remove/destroy a resource
What’s the difference between PUT and PATCH…?
Think “flat tire”:
- PUT a whole new tire on (replaces the entire resource)
- PATCH the existing tire (only replace the part you need)
URI
- Uniform Resource Identifier
The portion of the URL after the domain.
For the URL https://en.wikipedia.org/wiki/Uniform_Resource_Identifier, the domain would be https://en.wikipedia.org and the URI would be /wiki/Uniform_Resource_Identifier.
Think to yourself
What is the Domain and URI for this address? http://www.tatteredcover.com/book/9781626722934
Put it all together and you get… Five RESTful API Routes!
AKA what you need to know about REST
- get /resources => resources#index
- get /resources/:id => resources#show
-
post /resources => resources#create
- patch /resources/:id => resources#update
- delete /resources/:id => resources#destroy
There are also two additional routes that return webpages for forms to create and edit objects. We haven’t used these yet because we are building APIs:
- get /resources/new => resources#new
- get /resources/:id/edit => resources#edit
Notes:
- The routes often start with a namespace and version
- The resource name is plural
- /resources represents the whole table
- /resources/:id represents one row in the table
- Can also have nested resources
- ex: /artists/:id/songs
- All the songs for a specific artist
The Web Before REST
No rules! Make whatever URLs you want!
- get /articles/new => articles#make_a_new_one
- post /articles/write => articles#make
- get /articles/create => articles#new
- post /articles/save => articles#sophia
- put /articles/1/destroy => articles#index
- delete /articles/destroy&id=1 => articles#BALEETED
These are not RESTful routes
Are these routes good or bad? Why?
Identifying RESTful Routes in Rails
Pull up your Task Manager application.
Create a table for 5 RESTful routes, allowing us to perform all CRUD actions on a Task.
When finished, add a few non-RESTful routes. What makes a route non-RESTful?
Is there an easier way to see all the routes in a Rails app?
Yes!
rails routes
CFU
If asked in a technical interview, how would you answer the following questions?
- What is each part of CRUD?
- What is REST?
- How do we combine CRUD and REST in web applications?
