Wednesday, 2 April 2008

Advancing with Rails course - Day 3 - pt3

Final blog for day 3 (I'll probably end up summarising a lot of this is a presentation to foomongers, so I'll post the slides if I do. However, for now:

We started to look at REST.

Just a few notes- not in any structure. A good resource to read is Roy T. Fielding's dissertation (http://www.ics.uci.edu/~fielding/)

Representational State Transfer

request sequence (slide 198)

by default

link_to => GET
form_for => POST

link_to with movie_path => GET
link_to using edit_movie_path => GET

as browsers don't issue PUT and DELETE requests, rails cheats with:

to get PUT:
form_for with :url => movie_path(@movie) and :html => (:method => "put")
you get => method="post", intput type="hidden" name="_method" value="put"

to get DELETE
link_to wih item_path(@item), :method => "delete"
you get => DELETE (but wrapped in a form so that spiders don't follow it)

REST and CRUD have no actual real connection, but when brought into rails, then they meet up,
because it has been orchestrated

And then finally during the day onto some Ajax stuff

Ajax:

Ajax request happens overall with in the cycle of a request

link_to_remote "Click me", :url => {....}
-> goes to server, does stuff C/A -> sends back to client

typically, not a whole cycle, as only sends back a snippet/fragment which you want to drop into your document

link_to_remote "Click me", :url => {:action => click_me}, :update => "mydiv"

so drops it into a div entitled mydiv

def click_me
render :partial => "clicked"
end

renders the partial and drops it in

link_to_remote "Click me", :url => {:action => click_me}, :div => "mydiv"

as no update

def click_me
@div = params[:div]
@del = Auction.delete(params[:id])
end

hands off to click_me.rjs

if @del.zero?
page.alert("Destroy operation failed")
else
page.visual_effect :shrink, @div, :duration =>1
page.delay(2) do
page.alert("That auction is history!")
end
end

page sends back the javascript to do what you want

form_remote_for :item, :url => {:action => :update}, :update => "mydiv"

flash is normally waiting for the next request cycle

flash.now[:notice] will have it come through to the ajx response there and then, rather than wait for the page refresh

raise request.xhr? method which means is this an ajax request, which means that you can fork on the request.

name.html.erb will take preference over name.rjs, so you either shouldn't have them with the same name,
or render rjs directly in the controller

render :update do |page|
page.alert("Hello")
end

which would bypass that issue

you can put rjs directly in the view to get javascript directly in the page

xhr requests are post by default, so if you are requesting a view only allowed by get, put or delete, then you need to explicity state this in the link_to_remote tag

1 comment:

Lars said...

Wiked. Almost the same as being there. Felt bad having to leave during Ajax stuff. Hope this workshop things is worth it.

What your company slogan?
Vampire Software - We suck our clients dry! ;)