Rendered partial is not visible? - ruby-on-rails

So I'm passing down locals to a partial via PublicActivity and try to render the partial on the users/show.html.erb file, like so:
<% #activities.each do |act| %>
<% render partial: "posts/#{act.trackable.check_type}",
locals: { tweet: tweet.trackable }%>
<% end %>
But this results into nothing. I don't see the partial at all. It's not visible. All data that is passed down is not nil, double confirmed via byebug and rails console.
Any ideas what could cause the invisibility of the partial?

<% %> Executes the ruby code, but doesn't print it.
<%= %> Prints the result into the erb file.
So, the code should be:
<%= render partial: "posts/#{act.trackable.check_type}",
locals: { tweet: tweet.trackable }%>
More:
<%# %> : is for comment in erb

Related

Ruby on Rails if/unless statment for AJAX destroy when cart is empty

I am building webstore. I added a bit of AJAX functionality to add, update and remove items from my cart without refreshing.
It works perfect as long as there are no items in a cart and render cart_empty partial properly.
The problem is when I add few items, and I can update/remove them without refreshing and
finally I remove the last one, and it do not switch to the cart_empty partial and there are only empty table headers left from cart-items partial.
Can I add some logic to destroy.js.erb?
destroy.js.erb
$("#cart-item").html("<%= j render 'carts/cart_items' %>");
the show.html.erb contains this unless function:
<% unless current_order.order_items.empty? %>
<div id="cart-item">
<%= render 'cart_items' %>
</div>
<% else %>
<div id="cart-empty">
<%= render 'cart_empty' %>
</div>
<% end %>
Maybe should I modify somehow my controller to check if there are order_items in a current_order?
Thank you!
A JS.erb template is evaluated in exactly the same way as a HTML template. So you can just add a condition:
<% if current_order.order_items.any? %>
$("#cart-item").html("<%= j render 'carts/cart_items' %>");
<% else %>
$("#cart-item").html("<%= j render 'carts/cart_empty' %>");
<% end %>
None that this implies that current_order is either a helper or a local passes to the view.
But you might want to refactor this and push the condition down to the partial:
# carts/cart_items.html.erb
<% if cart_items.none? %>
<% render :cart_empty %>
<% else %>
# ...
<% end %>
Which will let you just write:
<%= render 'carts/cart_items', cart_items: current_order.order_items %>
See:
Layouts and Rendering in Rails - passing local variables

Rendering collections within collection in Rails

This is driving me crazy, I thought it should be something very simple but I've spent all day trying to figure it out and getting nowhere. I've looked all over, there's something I must be missing.
I want to render a partial for a collection, within a partial from a collection.
Eg. I have a collection of entries which I want to render in my feed partial, I want feed to come from a collection of feeds, such that the page displays all entries in all feeds.
How can I do this?
Something like:
controller:
#feeds = Feeds.all
allmyfeeds.html.erb
#feeds.each do |feed|
<%= render 'feed' %>
<% end %>
or
<%= render 'feeds', collection: #feeds %>
_feed.html.erb
<%= render 'items', collection: #items %>
_item.html.erb
<%= item.summary.html_safe %>
But I really don't know.
Partial naming conventions will really help you out here...
In allmyfeeds.html.erb (which i'm guessing is actually feeds/index.html.erb), instead of this...
#feeds.each do |feed|
<%= render 'feed' %>
<% end %>
You can simply call this...
<%= render #feeds %> # this will invoke _feed.html.erb for every feed in the collection, automatically
Inside your _feed.html.erb partial...
# Note: You may need to change `items` to something like `items/items` if it is not located in the same directory
<%= render partial: 'items', locals: { items: feed.items } %>
Then in your items partial, you will have access to items, which is a collection of items for that particular feed
Somehting like:
<% #feeds.each do |feed| %>
<%= render partial: 'feed', locals: { feed: feed } %>
<% end %>
In your _feed.html.erb:
<h1><%= feed.id %> </h1>
<% feed.entries.each do |entry| %>
<&= render partial: 'entry', locals: { entry: entry } %>
<% end %>
In your _entry.html.erb:
<h2><%= entry.id %></h2>
I'm assuming your Feed model has a has_many :entries association, if it's not the case (and what you want is to render the same collection of #entries in each feed), then you just need to pass the #entries collection to the _feed.html.slim partial, like:
render partial: 'feed`, locals: { feed: feed, entries: #entries }
and update your _feed.html.erb

Nesting an each loop within an ERB rendered layout is not iterating over any elements

I have a common sublayout that I use on many pages in my application. To render it, I use render layout: ... and then put the rest of the view in the block:
<%= render layout: 'layouts/content-box', locals: { header: 'Foo' } do %>
<% #posts.each do |post| %>
<%= post.inspect %>
<% end %>
<% end %>
This produces an empty template, in fact the loop does not iterate at all. This used to work, but we are currently moving from HAML:
= render layout: 'layouts/content-box', locals: { header: 'Foo' } do
- #posts.each do |post|
= post.inspect
I thought that the HAML I have posted was the equivalent, but obviously not. If I move the loop outside of the render block, then it works. The array is there and populated. What am I doing wrong? I have tried using <%- #posts.each %> as well (notice the hyphen). Nothing seems to be working.
Gahhhh, it was because the layout that I was trying to render was still a HAML file. Once I converted it to an ERB as well, everything worked as expected.

check if Rails partial is empty

I have a main page that is responsible for HTML/CSS styling, but some of the contents come from partials. A partial receives some locals or params, i.e. current_user or person, and displays information if any.
Is there a way for me to check if a partial rendered anything? My end goal is something like this:
<% if my_partial can render something %>
<div class="css_for_something">
<%= render(partial: 'my_partial', locals: {...} ) %>
<% else %>
<div class="css_for_no_info">
<%= render something else %>
<% end %>
I do not want the partials to handle styling logic; they just need to display content if any. Conversely, the main page should not know anything about the logic in the partial(s), such as checking values or querying the database.
Thank you
Unfortunately, Chris Peter's solution did not work for me on rails 4.2.4, as render_to_string seems to not be available in views.
However, the following worked (rails 4.2.4):
<% partial_content = render partial: 'my_partial' %>
<% if partial_content.present? %>
<%= partial_content %>
<% else %>
<%# rendered if partial is empty %>
<% end %>
Be aware that the present? check really only checks if what was rendered is empty. If, something, e.g. a HTML comment, is returned, the check returns false.
Try storing the value generated by render_to_string in a variable:
<% partial_content = render_to_string(partial: 'my_partial', locals: {...} ).strip %>
Then you can see if it contains any content:
<% if partial_content.present? %>
<%= partial_content %>
<% else %>
<div class="css_for_no_info">
<%= render something else %>
</div>
<% end %>

ruby on rails render deosn't find the file

I'm new to ruby on rails.
In views/events I have "_form.html.erb" which is rendered in "new.html.erb" by this code:
<%= render "form" %>
Now I want to render "_form.html.erb" in "index.html.erb" which is in the same folder(views/events).
But I get the error "missing template".
I guess I have to add some thing to controller, please help me to render form in other pages of views...
You "usually" don't render a form in an index action. Most form partials are setup semantically to expect a #my_resource, but if you're doing everything the rails way you're not going to have a instance variable during your index action. There's a number of ways you can do this but this is probably the quickest.
You probably have some collection (let's pretend you're using books) in your index action:
#views/books/index.html.erb
<% #books.each do |book| %>
...
<%= render "form" %>
...
<% end %>
You can just set an instance variable somewhere prior to rendering the form:
#views/books/index.html.erb
<% #books.each do |book| %>
<% #book = book %>
...
<%= render "form" %>
...
<% end %>
Another way to do it would be through passing in some locals to a partial. You'd have to change all of your references in _form to use a local variable instead. Then you can call render like this:
<%= render :partial => "form", :locals => {:book => book } %>
You can try
<%= render "events/form" %>
I had this problem before and this solved

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