#link_to

I have read so many articles, documents, stackover flow, wiki, github nearly a week. Still I have a little confuse, but finally I can pass my rails link_to multiple params to ajax at js file. :-) 

Before:  home.html.erb

<%= link_to (image_tag(image.thumbnail_url, :size => '75x75')), largeimage_path(limageurl: image.original_url, limageid: image.id, limagetitle: image.title), remote: :true %>

photos_controller

def largeimage @largeimageurl = params[:largeimageurl] @largeimageid = params[:largeimageid] @largeimagetitle = params[:largeimagetitle] choice = {     :largeimageurl =>  params[:limageurl],    :largeimageid =>   params[:limageid],     :largeimagetitle =>   params[:limagetitle] } respond_to do |format|       format.html {}       format.js {render :json => choice }       format.json {render :json => choice }  end  end

photo.js 

$(function(){   console.log('test');   $('.single_image a').bind('ajax:success', function(event, data, status, xhr) {    var x = JSON.stringify(data);   alert(x);  });

In photo.js, JSON.stringify(data) can change the object to json string. But the issue is more than before step. In js file, ajax cannot get any data from rails. So, if I console out the data here, just say [object object], and if its changed to console.log(data.largeimageid); , then console shows null. 

I had no idea which parts were wrong (actually all of them, needs to fix up). 

Now:  Write link_to multiple params to jQuery-ujs way.  home.html.erb 

<%= link_to (image_tag(image.thumbnail_url, :size => '75x75')), largeimage_path, data: {remote: :true, type: :json, params: {limageurl: image.original_url, limageid: image.id, limagetitle: image.title}.to_param} %>

this HTML format is: 

<a data-remote="true" data-type="json" data-params="limageid=15455416588&limagetitle=IMG_20140328_175650&limageurl=http%3A%2F%2Ffarm6.staticflickr.com%2F5609%2F15455416588_677669f2f7_m.jpg" href="/largeimage"><img src="http://farm6.staticflickr.com/5609/15455416588_677669f2f7_s.jpg" alt="15455416588 677669f2f7 s" width="75" height="75" /></a

jQuery-ujs can handle  custome data-* attribute.  Also, add data-type as json. I thought controller can handle this encoding part, but if I add this data-type, then ajax get the correct data from rails. So, this is the key for my code. 

photos_controller 

def largeimage        choice = {      :largeimageurl =>  params[:limageurl],      :largeimageid =>   params[:limageid],      :largeimagetitle =>   params[:limagetitle]    }    respond_to do |format|      format.html {}      format.js {render :json => choice }      format.json {render :json => choice }    end   end

photo.js 

$(function(){     $('a[data-remote]')      .bind('ajax:success', function (event, data, status, xhr) {         alert(data.largeimageurl);        console.log(data.largeimageid);        console.log(data.largeimagetitle);     })    .bind('ajax:complete', function (xhr, status){       console.log("Completed!");     })   .bind('ajax:error', function (xhr, status, error){       console.log("Somthing wrong!!");   });      return false; });

I read too much of documents to remember which parts were coming from, and now I lost the reference sources.  Once, I find the reference, I will update in here. 

Have you ever wanted to add an icon of some sort to a link, but couldn't figure out how to add that <span><i class='glyphicon glyphicon-star'></i></span> in there?

The solution is to use the link_to helper as a block!

The formal syntax, as seen in the link_to documentation, is:

link_to(options = {}, html_options = {}) do # name end

And translated into a more concrete example in an ERB template, it looks like:

<%= link_to your_path, class: 'your-class' do %> <span><i class='glyphicon glyphicon-star'></i></span> <% end %>

you can typing like this:

<%= link_to "Trash", account_path(@account, trash: true), method: :put %>

with this path:

/account/[account_id]?trash=true

it will post update on AccountsController like this

def update    @account = Account.find(params[:account_id])    @account.update_attributes(trash: params[:trash]) end

when you use update_attributes(params[:account]) in controller try below instead:

def update    @account = Account.find(params[:account_id])    @account.update_attributes(params[:account]) end

<%= link_to "Trash", account_path(@account, account: { trash: true }), method: :put %>

Controllers

Controller's main function is to control things. Two main parts of it:

The flow of the application

Gather data that it needs (from model and such)

All the View does is formats the things for the output. In order to access data that is gathered by the controller instalce variables (object - controller variables) are used. This variables are set in the controller.

Note: There is no way to go back from the View to the Controller to set something up. Everything must be preset in the Controller for the View to use.

Rendering Templates

How does the controller decides which template to use?

Rails checks if there is any Action that is associated with the request. And if not checks if there is a View for it. If so, even without an action being present rails renders the view.

Render Method

Each action of your controller by default will have a render method executed with the defaults implicitly, if nothing else is specified. That means that the view with the action_name.html.erb under the controller's name folder in the views directory will be rendered for you automatically.

There are a variety of ways to customize the behaviour of render. You can render the default view for a Rails template, or a specific template, or a file, or inline code, or nothing at all. You can render text, JSON, or XML. You can specify the content type or HTTP status of the rendered response as well.

Her are multiple ways to render a view:

render(:action => 'hello')

render(:template => 'demo/hello')

render('demo/hello')

render('hello')

It might be a little confusing, but render(:action => 'hello') doesn't actually calls hello action, what it does is it renders a default template for the hello action, without executing the action itself.

  So it will be an equivalent for all the other render examples in the above list.

The last two were added in Rails 3 and are now considered a best practice to use.

More on Render (Rails docs)

Redirect

Redirect is part of the http protocol itself. What Rails does when you are use it's redirect_to method is it send a request back to the browser with the HTTP status code: HTTP/1.1 302 Found and send a Location that it wants the request to be send to, e.g.: Location: http://localhost:3000/demo/hello. So the browser initiates a new request to the new location (all of the processing from the action before the redirect_to was called is lost.)

View Templates

Dynamic Templates with embedded Ruby code (ERb).

hello.html.erb Template name: hello Process with: ERb Output format: HTML

You Embed Ruby code with special tags: <% code %> and <%= code %>. To output Ruby variable you use #{variable_name} inside a double quoted string. E.g.:

<% name = "Alexander" %> <%= "My name is #{name}" %>

Note: you can't use puts and gets in the ERb, those output to the console and not to the generated html. Instead you use <%= %>.

Instance Variables

This are used to pass the data pulled together by the controller in the corresponding view.

Instance variables are variables of an instance of a class (object) and since a Rails controller is simply a class, instance variables are instances of the controller.

Instance variables are marked with an @ sign, e.g.: @instance_variable_name.

Link_to Method

In Rails templates you can use regular <a href="demo/action">Link</a> html links. However it is much more common to use Rails method link_to for that. E.g.: <%= link_to(text, target) %>

Text is the text to be displayed as a link. And target is where the url is going. You can specify the regular "controller/action" as target, but note that it can take Ruby hashes as well.

The syntax to do that is: {:controller => 'demo', :action => 'index'}. You can simply pass the action part, if the url is within the same controller.

The cool thing about this is that routes file is being used to form your url, same way as for the requests coming in.

Additional URL Parameters

When we need to pass additional url parameters like in: http://localhost:3000/demo/hello/3?page=3&name=kevin, we can simply use the same hash notation as we can use with link_to. Everything after the :action will be treated as parameters, e.g.: {:controller => 'demo', :action => 'hello', :id => 1, :page => 3, :name => 'kevin'}.

Note: that since ID is set to have a different meaning in our routes file (match ':controller(/:action(/:id(.:format)))'), the way the it will be appended to the url is different (/#{id} instead if /?id=#{id}).

Another point to note here is that all the url parameters (GET) and POST parameters are send to the system as strings, so in order to do any manipulation with them as integers, you would ned to cast them to such (.to_i).

All the parameters (including controller and action names) are accessible in the Rails/Ruby code using the special params hash.

You can simply access the values of it by passing either a name of the parameter you are looking for as a symbol or a string, e.g.: params[:id] or params['id'].