In my Rails app there are experiment instances and each experiment has attachments, which are represented as binary blobs in the database and can be quite big. This question is about efficiency in coding a link_to show the attachment.
Originally I had this:
<%= link_to #experiment.attachment.file_name, #experiment.attachment %>
However I was told that the Rails app would be more efficient in rendering the page with
<%= link_to #experiment.attachment.file_name, {:controller => :attachments, :action => :show, :id => #experiment.attachment_id}, {:method => :get} if ! #experiment.attachment_id.nil? %>
The justification is that the first version fetches the attachment from the database, and the second one does not, making it is better, albeit longer and uglier. Is this true?
Both versions accomplish the same thing in directing the user to the show page for an attachment and I was under the impression the first is the default way to do a link_to a record show page.
Is there a way to shorthand the second piece of code to make it less terrible with code in the view?
Try using a rails route helper, use rake routes to view all your routes and then you can get something like this (don't forget to apped _path to route):
experiment_attachment_path(#experiment.attachment)
I would express this using the route path rather than using the ActiveRecord instance to load so the view can use its to_param method (which is what it is doing under the hood).
<%= link_to #experiment.attachment.file_name, attachment_path(#experiment.attachment_id) %>
Related
I want to create a href tag like href=contacts/create. In my contacts_controller, I have a create GET action. I know this is against rails convention. I still need to create the above link using options = {controller=> 'contacts', action=>'create'}. It works for any other arbitrary action name
You can the hardcoded path option:
<%= link_to "Create", "contacts/create" %>
or the Rails generated path option:
<%= link_to "Create", { controller: "contacts", action: "create" } %>
This is not just against Rails' convention, but against sounds HTTP usage. This often causes serious problems that you can't predict in advance. Web crawling is just one of them, where something like the Google bot accidentally creates a new contact in your database, simply by crawling the page. Or script kiddies who find you have a create link, and send 100,000 clicks to it in quick succession.
Numerous other issues happen like this, including, at one well-known time, Google Chrome pre-fetching GET urls from the page to "speed up the user experience"; this was felt far and wide by sites that had used this technique. It's not an idle warning or a style issue: this can have a disastrous impact on your site.
First off this is really bad idea since GET requests should be idempotent. You're not just flouting convention - you're setting yourself and your users up for a really bad time since for example pressing the back and forward buttons will cause resources to be created - over and over. And there is guaranteed a better way to solve whatever you are trying to do such as:
# a "discrete form"
<%= button_to "Create contact", contacts_path, method: :post %>
# or use the rails ujs
<%= link_to "Create contact", contacts_path, method: :post %>
If you ABSOLUTELY have do this:
Rails.application.routes.draw do
get "contacts/create"
end
You can now do:
<%= link_to "Create", { controller: 'contacts', action: 'create' } %>
Congratulations, you broke the internets.
Like you mentioned, this is against rails convention, but if absolutely necessary, you can do this from your controller:
options = {controller=> 'contacts', action=>'create'}
view_context.link_to url_for(options)
If you need the href to only be the path, you can do:
options = {controller=> 'contacts', action=>'create'}
view_context.link_to url_for(options.merge(only_path: true))
I have a form to update an attribute of a model - I don't want it to go to the standard update action I want it to go to a different action.
<% for car in #cars %>
<%= form_for car, :url => { :action => "custom_action/#{car.id}" } do |f| -%>
This is giving the following error -
No route matches {:action=>"custom_action/1", :controller=>"cars"}
However if I visit the url - custom_action/1 - I don't get the routing error.
Any idea why I can't do this?
In addition to what Frederick Cheung said about GET vs POST vs PUT, I think your code might be wrong in general.
To do exactly what you want, try:
form_for car, :url => {:action => "custom_action", :id => car, :controller => "cars"} do |f|
I don't think this is a good idea, and will probably cause you pain. I suggest taking a look at the Ruby on Rails Routing Guide, to understand how to do this properly. (Routing is a topic where I always have to consult the manual.)
With correct routes your code should look something like this:
form_for car, custom_action_car_path(car) do |f|
Which will be easier to change in the future if/when you refactor your app.
If you go to the url by typing it into the url bar, you're making a GET request, whereas forms emit POST requests by default, and in this case would probably emit a PUT request (since you're acting on an existing record).
It sounds like your route is only routing GET requests. Given that you say your custom action does update the record, it sounds like you should update your routes to accept PUT requests instead.
I want to use the link to function to point to a form.
i.e <%= link_to 'Reports', '/reports/index.html.erb' %>
But this gives me a error saying no route matches '/reports/index.html.erb.
Thanks,
Ramya.
Rails doesn't like having the document format in the URL unless it's necessary (like when one action can handle multiple request formats). If you have reports/index.html.erb, the route to it would look like one of these:
match 'reports' => 'reports#index' #=> 'yourdomain.com/reports'
match 'reports/index' => 'reports#index' #=> 'yourdomain.com/reports/index
Then your link would be:
<%= link_to 'Reports', 'reports' %>
or
<%= link_to 'Reports', 'reports/index' %>
If you really wanted to have the .html, you could probably do it like this:
match 'reports/index.html' => 'reports#index' #=> 'yourdomain.com/reports/index.html
or
match 'reports/index.:format' => 'reports#index' #=> 'yourdomain.com/reports/index.html
But the .html is meaningless in the first case and unnecessary in the second. I don't recommend doing it this way, as it's not standard Rails practice.
I highly recommend you read this tutorial on Routing, at least the first few sections, before you move forward. It's an absolutely essential part of Rails, and if you don't understand how it works, you will never be a productive Rails programmer.
The link should point to the form from the server's point of view. Try <%= link_to 'Reports', '/reports/index.html' %> (without the '.erb')
Make sure that your routes really define that url. I guess it may be '/reports/' instead of '/reports/index.html', but YMMV.
Consult the output of command rake routes to see what routes are defined.
I'm working in a rails app (rails 2.3.8), and I created a resource called articles. I need a form who call the create action in that controller. I used a form_remote_tag, but I can't call correctly the "create" action, the app always call de "new" action.
I used several different combinations, the last one is this
<%=form_remote_tag :html => { :action => url_for (:action => :create)} %>
How a could do this?.
I can't use the for_remote_for or the form_for because that form will feed more tan one table in my database.
Thanks in advance
You are over complicating it:
<%= form_remote_tag :action => :create %>
Also, be sure that this is what you truly need. You say you want to create multiple objects in the form, which is why I think you may be after form_remote_for coupled with fields_for rather than form_remote_tag, but from your question I don't fully understand.
I'm creating in my index page of my ruby on rails program, a list of the most commonly searched for terms in my database and hence each time a user selects a specific category this is written to another database.
What i would like it to create a hyperlink and pass a certain amount of parameters to a form like is usually done with a select_tag but instead with just a hyperlink, i would like to pass a set of hidden fields that i have on the page as well as what the user has selected.
To give you a better idea, basically i have the following structure in my program:
User inputs a search on (index.html.erb), user clicks on submit tag
action, user is taken to search.html.erb page and is displayed a set of refined categories + some fields, submit button,
user is taken to closest.html.erb (which uses parameters from the previous form by invoking the params[:searchSelected] and a few other params. )
I would also like to add this functionality:
Mimick this same operation, but instead of going in the search.html.erb, i would click on an already refined search category on the index.html.erb page (from a link_to , transmit as parameters which link_to the user has chosen + the hidden fields.
i Currently have this code
#stats.each do
|scr|%>
<%= link_to scr.category, :action => 'closest', :id => scr.category%>
I'm not sure if this is relevant, but i currently have the following routes in my routes.rb file
map.resources :stores, :collection => { :search => :get }
map.connect ':controller/:action/:id'
map.connect ':controller/:action/:id.:format'
would anyone please assist me please? this is my first ruby on rails project and i would really like to find a way around this please
I am not sure if this is what you were thinking, but you can add additional parameters to the link_to tag. They are then available in your controller. So:
<%= link_to scr.category, :action => 'closest', :id => scr.category, :other_param => "test" %>
Will be available in your controller.
def closest
params[:other_param] == "test" #this will be true
end
i managed to resolve this by taking the params[:id] and then according to the value either set my own values (instead of the hidden ones in the index.erb which i had set manually anyway) and otherwise, continue as usual had i placed a regular search
View:
<%= link_to obj.ptc_devicename ,"/wiuconfig/hd?idval=#{obj.id.to_s}&val=#{#devicetype}",:value => obj.ptc_devicename,:id =>obj.id %><br/>
Controller:
#Heading= params[:val]
#id=params[:id]
value will be id is 2 and val is #devicetype