Understanding Rails "magic" with regards to rendering partials (and passing locals into them).
Why does this work:
<%= render "rabbits/form" %>
And this work:
<%= render "rabbits/form", :parent => #warren, :flash => flash %>
but this does not work:
<%= render "rabbits/form", :locals => { :parent => #warren, :flash => flash } %>
But this does:
<%= render :partial =>"rabbits/form", :locals => { :parent => #warren, :flash => flash } %>
Also, how can I look up these nuances so I don't need to bother people on S.O.?
The short answer is the render method looks at the first argument you pass in. If you pass in a hash (which includes :partial => 'foo', :locals => {blah blah blah}) then it will pass in all of your arguments as a hash and parse them accordingly.
If you pass in a string as your first argument, it assumes the first argument is your partial name, and will pass the remainder as your locals. However, in that subsequent call, it actually assigns :locals => your_locals_argument, which in this case is the entire :locals => {locals hash}, instead of just {locals hash}; i.e. you end up with :locals => {:locals => {locals hash}}, rather than :locals => {locals hash}.
So my advice is just to always explicitly pass values the same way all the time, and you won't have problems. In order to learn about this, I went directly to the code itself (actionpack/lib/base.rb, render() method in Rails 2; Rails 3 is different). It's a good exercise.
Furthermore, don't worry about "bothering" people on SO. That's why this site exists. I even learned something from this.
if you need to specify :locals, you need to specify :partial or :template
<%= render :partial => "rabbits/form", :locals => {...} %>
should work
To be honost, I only know about these use cases, because I have been keeping up with Rails for the last couple of years and read the announcements that a new way of doing it has been added. I often make a mistake in it myself, but usually it's easily corrected.
It's one of those parts of Rails API that hasn't been thoroughly thought through, if you ask me. It just accumulated more and more syntactic sugar over the years, without deprecating any of the old behavior. The render method has diabetes.
To make it even worse, render behaves differently in controller and view. I also looks at the first argument's content to see if it's a file, template, action or partial. If it starts with a slash then it's a file, or something like that.
I am in favor of using the shorter notation whenever possible. Because the short notations do communicate the intent quite well. When reading it, it usually does what you think it does. Writing partials is not straight forward.
Here is the source of render method from http://api.rubyonrails.org/classes/ActionView/Rendering.html#method-i-render:
def render(options = {}, locals = {}, &block)
case options
# Here is your last case
when Hash
if block_given?
_render_partial(options.merge(:partial => options.delete(:layout)), &block)
elsif options.key?(:partial)
_render_partial(options)
else
template = _determine_template(options)
lookup_context.freeze_formats(template.formats, true)
_render_template(template, options[:layout], options)
end
when :update
update_page(&block)
else
# here the first three cases
_render_partial(:partial => options, :locals => locals)
end
end
Hope this help!
Related
There's this button / link in my web app. It's a button for a pizza - margherita with price, ingredients, and category, all already loaded to the db. Clicking this button loads the item's id to params, which is then used to find the object.
I want the click to launch the following chain of events:
Load the id
Find the object by id
Instantly render the object and its attributes in adjacent div on the same site.
Is this possible without JavaScript, just Ruby on Rails?
I am stuck at point 3. I have an idea, but incomplete. Please, give me a hint.
PS. My idea is to render views for index and show in separate divs next to one another.
#NickM, I added your code and it's throwing ActionController::UnknownFormat error, pointing at respond_to do |format| in show_pizza method.
Here's my pizzas/index.html.haml:
%h1= t :all_pizzas
- #pizzas.each do |pizza|
= render pizza
.orders
%h1 Orders
And pizzas/_pizza.html.haml:
%tr
= link_to pizza.name, show_a_pizza_path(pizza.id), :method => :post
%br/
I am getting this error upon clicking the link in _pizza.html.erb. My show_pizza.js is now:
pizza_div = $("#orders");
pizza_div.html( "<%= j render( :partial => 'pizzas/pizza', :locals => { :pizza => #pizza } ) %>" );
What am I missing? Sorry, I don't know js.
The short answer is no. When the link is clicked you will need to either render another page or handle the data returned by the controller with Javascript. The best option would be to set up an action that responds with JSON and parse what you get back on the front end.
Even after your P.S. you will have to handle the response from the server with Javascript, unless you are okay with rendering a new page. You need to post some code, preferably routes and controller action. This would also work:
<%= link_to("Show Pizza", show_a_pizza_path(#pizza.id), :method => :post, :data => {:remote => true}) %>
routes.rb
post 'show_pizza/:id' => "pizzas#show_pizza", :as => :show_a_pizza
pizzas_controller.rb
def show_pizza
#pizza = Pizza.find(params[:id])
respond_to do |format|
format.js
end
end
views/pizzas/show_pizza.js
pizza_div = $("#the_name_of_your_div");
pizza_div.html( "<%= j render( :partial => 'pizzas/pizza', :locals => { :pizza => #pizza } ) %>" );
and then put the pizza markup in /views/pizzas/_pizza.html.erb
this is my simple code
<%= render :partial => '/manage/regions/get_by_country', :locals => {:country_id => #last_search.country_id} %>
the #last_search.country_id has value (checked)
but while rendering the control seems that the country_id is null or empty
what i cant understand is that i use same syntax in another control and work us expected
i try also add hardcoded country_id
<%#id = 118%>
<%= render :partial => 'manage/regions/get_by_country', :locals => {:country_id => #id} %>
<%end%>
and not working
the control rendering but the country_id is null
OK i got the problem
the variable on the partial named #country_id
and i passed country_id (with no the '#')
i actually don't know why in one controller its work and on the other it doesn't work
but when i change the variable on the partial to country_id (with no the '#')
its work as expected
thanks
I was trying to limit the rendering of partial collection, but I cannot change the controller or model (don't ask why, it's hard to explaint). So I have to limit it in view and only solution I could come up with is this
def suggested
#suggested ||= current_user.suggested_friends
end
<%= render :partial => 'layouts/three_panel_widgets/friend', :collection => suggested[0..3] %>
do you have any better ideas ?
If you are using rails 3, you can use suggested.limit(4). It will generate a SQL with LIMIT clause. This is a little bit better then using suggested[0..3].
<%= render :partial => 'layouts/three_panel_widgets/friend', :collection => suggested.limit(3) %>
I have a view on my current project which does something like the following(in haml):
-#horses.each do |horse|
= render :partial => 'main/votingbox', :locals => {:horse => horse}
The in the _votingbox.html.haml file I have the following:
%div.votingbox
%span.name= horse.name
%div.genders
- if horse.male
%img{:src => 'images/male.png', :alt => 'Male'}
- if horse.female
%img{:src => 'images/female.png', :alt => 'Female'}
%div.voting_form
= form_for(Vote.new, {:url => horse_vote_path(horse)}) do |f|
= f.label :comment, "Your opinion"
= f.text_field :comment
...
a bunch of labels and input elements follow generated using the form helpers
This will generate working code but it does generate forms with the same ids for all the form elements which makes the HTML invalid once the votingbox partial is rendered a second time.
My first guess at fixing this was to specify a unique :id to form_for but that only applies to the form tag generated by form_for and not any of the tags inside the form_for block.
One definite solution to this problem is to go through and manually define my own unique ids on form_for and all the form elements I use. This is more work than I had hoped for.
Is there an easier or cleaner way to get unique ids in a similar format to the way Rails currently generates them on all my form elements?
I have removed the original answer as it is totally irrelevant to the updated version of the question.
Update: So now we know that you have an unsaved ActiveRecord object passed to the form_for call, the answer becomes simple: You can override any parameter that form_for generates. That includes the element id. And fields_for sets the context for a specific record.
= form_for(Vote.new, :url => horse_vote_path(horse), :id => dom_id(horse, 'vote')) do |f|
= f.fields_for horse, :index => horse do |fh|
= fh.text_field :whatever
…
You can override the autogenerated ids and names of all form_for content with :as like the following:
= form_for(Vote.new, :as => horse.name, {:url => horse_vote_path(horse)}) do |f|
= f.label :comment, "Your opinion"
= f.text_field :comment
So if a given horse.name is foobar, it will generate a comment field whose id is foobar_comment and name is foobar[comment]
But remember to make sure that the dynamic parameter is acceptable as an html id, a horse.name like hor$e is not acceptable as an html id and therefore might break something.
P.S: Sorry for answering very late, but at the time the question was asked, I haven't had learnt anything at all about rails! hope that might help someone out there!
I'm trying to use the scriptaculous helper method sortable_element to implement a drag-and-drop sortable list in my Rails application. While the code for the view looks pretty simple, I'm really not quite sure what to write in the controller to update the "position" column.
Here's what I've got in my view, "_show_related_pgs.erb":
<ul id = "interest_<%=#related_interest.id.to_s%>_siblings_list">
<%= render :partial => "/interests/peer_group_map", :collection => #maps, :as => :related_pg %>
</ul>
<%= sortable_element("interest_"+#related_interest.id.to_s+"_siblings_list", :url => {:action => :resort_related_pgs}, :handle => "drag" ) %>
<br/>
And here's the relevant line from the partial, "interests/peer_group_map.erb"
<li class = "interest_<%=#related_interest.id.to_s%>_siblings_list"
id = "interest_<%=related_pg.interest_id.to_s%>_siblings_list_<%=related_pg.id.to_s%>">
The Scriptaculous UI magic works fine with these, but I am unsure as to how to change the "position" column in the db to reflect this. Should I be passing the collection #maps back to the controller and tell it to iterate through that and increment/decrement the attribute "position" in each? If so, how can I tell which item was moved up, and which down? I couldn't find anything specific using Chrome dev-tools in the generated html.
After each reordering, I also need to re-render the collection #maps since the position is being printed out next to the name of each interest (I'm using it as the "handle" specified in my call to sortable_element() above) - though this should be trivial.
Any thoughts?
Thanks,
-e
I typically create a sort action in my controller that looks like this:
def sort
order = params[:my_ordered_set]
MyModel.order(order)
render :nothing => true
end
Don't forget to add a route:
map.resources :my_model, :collection => { :sort => :put }
Now, on MyModel I add a class method that updates all of the sorted records with one query (this only works in mysql, I think..):
def self.order(ids)
update_all(
['ordinal = FIND_IN_SET(id, ?)', ids.join(',')],
{ :id => ids }
)
end
The single query method comes from Henrik Nyh.