Building an API in Rails without Realizing It

Rails APIs
Monday, February 25, 13

@markbates

http://www.metacasts.tv
CONFOO2013


e b APIs
Rails
W

you’re probably
doing it wrong


Don’t Panic!

most APIs are an
after thought


we can prevent
that!


3 simple rules for
building an API


1. consume your
own API


2. document your
API


3. version your
API


building the API


Service Oriented
Architecture


SOA Pros


SOA Pros

• Scales Easily


SOA Pros

• Scales Easily

• Separate Concerns/Very Clean


SOA Pros

• Scales Easily


• Can be easier to maintain


SOA Pros

• Scales Easily



• Solid Architecture


SOA Pros

• Scales Easily



• Solid Architecture

• Easier to refactor/rebuild


SOA Cons


SOA Cons

• Can be more difﬁcult to maintain


SOA Cons


• More complex deploys


SOA Cons



• Managing several applications


SOA Cons




• Potential for ‘out-of-sync’ apps


SOA Cons




• Potential for ‘out-of-sync’ apps

• More difﬁcult to test integration


API Client


Client

API

Client


Client

API Client

Client


Client
Service 1

Service 2 Client

Service 3
Client


a quick detour


Rails encourages
poor API design!


#
POST
/todos

#
POST
/todos.json

def
create
class
TodosController
<
ApplicationController

@todo
=
Todo.new(params[:todo])

#
GET
/todos

#
GET
/todos.json

respond_to
do
|format|

def
index

if
@todo.save

@todos
=
Todo.all

format.html
{
redirect_to
@todo,
notice:
'Todo
was
successfully
created.'
}

format.json
{
render
json:
@todo,
status:
:created,
location:
@todo
}

respond_to
do
|format|

else

format.html
#
index.html.erb

format.html
{
render
action:
"new"
}

format.json
{
render
json:
@todos
}

format.json
{
render
json:
@todo.errors,
status:
:unprocessable_entity
}

end

end

end

end

end

#
GET
/todos/1

#
GET
/todos/1.json

#
PUT
/todos/1

def
show

#
PUT
/todos/1.json

@todo
=
Todo.find(params[:id])

def
update

@todo
=

respond_to
do
|format|

format.html
#
show.html.erb

respond_to
do
|format|

format.json
{
render
json:
@todo
}

if
@todo.update_attributes(params[:todo])

end

format.html
{
redirect_to
@todo,
notice:
'Todo
was
successfully
updated.'
}

end

format.json
{
head
:no_content
}

else

#
GET
/todos/new

format.html
{
render
action:
"edit"
}

#
GET
/todos/new.json

format.json
{
render
json:
@todo.errors,
status:
}

def
new

end

@todo
=
Todo.new

end

end

respond_to
do
|format|

format.html
#
new.html.erb

#
DELETE
/todos/1

format.json
{
render
json:
@todo
}

#
DELETE
/todos/1.json

end

def
destroy

end

@todo
=

@todo.destroy

#
GET
/todos/1/edit

def
edit

respond_to
do
|format|

@todo
=

format.html
{
redirect_to
todos_url
}

end

format.json
{
head
:no_content
}

end

end
end


Don’t Scaffold!


class
TodosController
<

def
index

@todos
=
Todo.all

end

def
show

@todo
=

end

def
new

@todo
=
Todo.new

end

def
edit

@todo
=

end

def
create

@todo
=

if
@todo.save

redirect_to
@todo,
notice:
'Todo
was
successfully
created.'

else

render
action:
"new"

end

end

def
update

@todo
=

if

redirect_to
@todo,
notice:
'Todo
was
successfully
updated.'

else

render
action:
"edit"

end

end

def
destroy

@todo
=

@todo.destroy

redirect_to
todos_path,
notice:
'Todo
was
successfully
destroyed.'

end
end


class
TodosController
<

inherit_resources
end


Inherited Resources
https://github.com/josevalim/inherited_resources


class
Api::V1::TodosController
<

respond_to
:json

before_filter
do

request.format
=
:json

end

def
index

@todos
=
Todo.all

respond_with
@todos

end

def
show

@todo
=

respond_with
@todo

end

def
create

@todo
=

if
@todo.save

respond_with
@todo

else

render
json:
@todo.errors,
status:

end

end

def
update

@todo
=

if

respond_with
@todo

else

render
json:
@todo.errors,
status:

end

end

def
destroy

@todo
=

@todo.destroy

head
:no_content

end
end


version your API!
Api::V1::TodosController
/api/v1/todos


i prefer URL
versioning


others prefer
header versioning


just pick one and
stick with it!


SOA Review


SOA Review

• We’ve cleaned up our code


SOA Review


• We know the API Works


SOA Review


• We know the API Works

• We’re now in a good place to scale


consuming the API


don’t use
Rails views


JavaScript

Cross-origin
Resource Sharing


rack-cors
https://github.com/cyu/rack-cors


module
YourApp

class
Application
<
Rails::Application

#
...

config.middleware.use
Rack::Cors
do

allow
do

origins
'*'

resource
'*',
headers:
:any,

methods:
[:get,
:post,
:put,
:delete,
:options]

end

end

end


JavaScript Pros


JavaScript Pros

• Scales Easily/Pushes processing to client side


JavaScript Pros




JavaScript Pros




• “Responsive/Native” feel for clients


JavaScript Pros




• “Responsive/Native” feel for clients

• Easily consumes your API


JavaScript Cons


JavaScript Cons

• Multiple languages (backend/front-end)


JavaScript Cons


• Difﬁcult to test integration


JavaScript Cons



• JavaScript


JavaScript Cons



• JavaScript

• Paradigm shift in architecture


JavaScript Cons
• Can be more difﬁcult to maintain • Accessibility issues



• JavaScript



JavaScript Cons

• Multiple languages (backend/front-end) • SEO concerns


• JavaScript



JavaScript Cons

• Multiple languages (backend/front-end) • SEO concerns

• Difﬁcult to test integration • !!Internet Explorer!!

• JavaScript



pick a
framework

don’t just
use jQuery

the big
three

Backbone.js

http://backbonejs.org/


ember

http://emberjs.com/


Angular.js

http://angularjs.org/


i can’t use
JavaScript


2 approaches

“compiled” sites


build your own
API library (and
open source it!)

class
TodosController
<

def
index

@todos
=
ApiLib::Todo.all

end

def
show

@todo
=
ApiLib::Todo.find(params[:id])

end

def
new

@todo
=
ApiLib::Todo.new

end

def
edit

@todo
=

end

def
create

@todo
=
ApiLib::Todo.new(params[:todo])

if
@todo.save

redirect_to
@todo,
notice:
'Todo
was
successfully
created.'

else

render
action:
"new"

end

end

def
update

@todo
=

if

redirect_to
@todo,
notice:
'Todo
was
successfully
updated.'

else

render
action:
"edit"

end

end

def
destroy

@todo
=

@todo.destroy

redirect_to
todos_path,
notice:
'Todo
was
successfully
destroyed.'

end
end


hey! there is
duplicate* code
now

is there? or did we
just move it
around?

Todo became ApiLib::Todo


we now have a
reference
implementation

make sure
to cache!!

The Hack

Please don’t
do this!


I’m Serious.

Don’t use
this hack!


I probably shouldn’t
even show you it.


Ok, I’ll show you,
but don’t tell
people where you
heard it.

class
TodosController
<

def
index

res
=
Api::V1::TodosController.action(:index).call(env)

@todos
=
JSON.parse(res[2].body).map
do
|data|

OpenStruct.new(data)

end

end

end


projects
worth noting

rails-api

api_doc

Final Thoughts


Final Thoughts

• Consume your API


Final Thoughts


• Version your API


Final Thoughts



• Document your API


Final Thoughts



• Document your API

• Did I mention consume your own API?


Thank You
http://www.metacasts.tv
CONFOO2013
@markbates

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