When I render a partial which does not exists, I get an Exception. I'd like to check if a partial exists before rendering it and in case it doesn't exist, I'll render something else. I did the following code in my .erb file, but I think there should be a better way to do this:
<% begin %>
<%= render :partial => "#{dynamic_partial}" %>
<% rescue ActionView::MissingTemplate %>
Can't show this data!
<% end %>
Currently, I'm using the following in my Rails 3/3.1 projects:
lookup_context.find_all('posts/_form').any?
The advantage over other solutions I've seen is that this will look in all view paths instead of just your rails root. This is important to me as I have a lot of rails engines.
This also works in Rails 4.
I was struggling with this too. This is the method I ended up using:
<%= render :partial => "#{dynamic_partial}" rescue nil %>
Basically, if the partial doesn't exist, do nothing. Did you want to print something if the partial is missing, though?
Edit 1: Oh, I fail at reading comprehension. You did say that you wanted to render something else. In that case, how about this?
<%= render :partial => "#{dynamic_partial}" rescue render :partial => 'partial_that_actually_exists' %>
or
<%= render :partial => "#{dynamic_partial}" rescue "Can't show this data!" %>
Edit 2:
Alternative: Checking for existence of the partial file:
<%= render :partial => "#{dynamic_partial}" if File.exists?(Rails.root.join("app", "views", params[:controller], "_#{dynamic_partial}.html.erb")) %>
From inside a view, template_exists? works, but the calling convention doesn't work with the single partial name string, instead it takes template_exists?(name, prefix, partial)
To check for partial on path:
app/views/posts/_form.html.slim
Use:
lookup_context.template_exists?("form", "posts", true)
In Rails 3.2.13, if you're in a controller, you can use this :
template_exists?("#{dynamic_partial}", _prefixes, true)
template_exists? is delegated to lookupcontext, as you can see in AbstractController::ViewPaths
_prefixes gives the context of the controller's inheritance chain.
true because you're looking for a partial (you can omit this argument if you want a regular template).
http://api.rubyonrails.org/classes/ActionView/LookupContext/ViewPaths.html#method-i-template_exists-3F
I know this has been answered and is a million years old, but here's how i ended up fixing this for me...
Rails 4.2
First, i put this in my application_helper.rb
def render_if_exists(path_to_partial)
render path_to_partial if lookup_context.find_all(path_to_partial,[],true).any?
end
and now instead of calling
<%= render "#{dynamic_path}" if lookup_context.find_all("#{dynamic_path}",[],true).any? %>
i just call <%= render_if_exists "#{dynamic_path}" %>
hope that helps. (haven't tried in rails3)
I have used this paradigm on many occasions with great success:
<%=
begin
render partial: "#{dynamic_partial}"
rescue ActionView::MissingTemplate
# handle the specific case of the partial being missing
rescue
# handle any other exception raised while rendering the partial
end
%>
The benefit of the code above is that we can handle tow specific cases:
The partial is indeed missing
The partial exists, but it threw an error for some reason
If we just use the code <%= render :partial => "#{dynamic_partial}" rescue nil %> or some derivative, the partial may exist but raise an exception which will be silently eaten and become a source of pain to debug.
What about your own helper:
def render_if_exists(path, *args)
render path, *args
rescue ActionView::MissingTemplate
nil
end
This works for me in Rails 6.1:
<% if lookup_context.exists?("override_partial", ['path/after/app/views'], true) %>
<%= render partial: "path/after/app/views/override_partial" %>
<% else %>
<%= render partial: "default_partial" %>
<% end %>
Here I have my partial nested some levels deeper than normal (app/views/path/after/app/views/_override_partial) so that's why I'm adding it as the prefixes array, but you can use lookup_context.prefixes instead if you don't need it.
I could have also used prepend_view_path on the controller. It's up to you :)
Related
I have a Users controller, with index, show, edit and destroy methods. In my layouts/ folder, I have a general-purpose user.html.erb layout that renders some partials. These partials are of course producing errors due some of the info isn't available, like #user.name, for example. I've tried to render that partial always when I'm in a def show state, something like:
<% if Users.show %>
<% render "shared/asides/users" %>
<% else %>
Other partials
<% end %>
I've tried several ways and I always get errors. I feel totally lost even trying to find out this on the Rails documentation nothing seems to be indicated there too.
Your problem is, as you say, you're trying to display things associated with a user, like #user.name, but there is no #user.
So why not check for #user before showing the partial? Or if you have a collection of users, I'm guessing #users?
<% if #users %>
<%= render "shared/asides/users" %>
<% else %>
<%= Do something else %>
<% end %>
Of maybe a bit neater:
<%= render (#users ? path/to/partial_a.html.erb : path/to/partial_b.html.erb) %>
You can make a special layout for your action. Then, at the end of action add layout to render.
def show
...
render layout: "custom_layout"
end
In my app/views/conversations/index.html.erb, I am writing:
<%= render #conversations %>
hoping that it would find a partial named _conversation.html.erb inside the same directory, and use it to render each elements in #conversations. (The usual Rails way)
But I get a missing template error: Missing partial mailboxer/conversations/_conversation.
I am using a Mailboxer gem, and there were no documentations for this. I know I could render a partial explicitly by <%= render partial: 'conversation', locals: { conversations: #conversations } %>.
Yet still, I would like to know why my app is looking for a partial for #conversations in mailboxer/conversations/, not conversations/, and if there is a way to change this behavior.
More information
<% #conversations.each do |conversation| %>
<%= div_for conversation %>
<% end %>
produces HTML:
<div class="mailboxer_conversation" id="mailboxer_conversation_16"> ... </div>
<div class="mailboxer_conversation" id="mailboxer_conversation_17"> ... </div>
....
Perhaps the mailboxer_ in front of conversation has something to do with this situation also?
This happens because, in later versions of Mailboxer, models are namespaced under Mailboxer. (e.g. Mailboxer::Conversation, Mailboxer::Message.)
I commented on the GitHub issue also.
You could try providing the full path to the partial, e.g.
<%= render :partial => "yourfoldername/conversation", collection: #conversations %>
I have a resource called Exercises in my application. I currently have a partial called _exercise.html.erb that I use to render them. I have an outlying case where I'd like to render them in a much different way. Can I make another partial for exercises that has this other format and still be able to use <%= render #exercises %>?
If not what is the best approach? Should I out a variable in the controller that tells the partial which layout to use, this would have both layout in one file and one if to decide. Or is there some better way?
If you'd like to use business logic to determine when to show what partial for your #exercises collection you should use the to_partial_path method in the Exercise model to define that. See #4 in this post: http://blog.plataformatec.com.br/2012/01/my-five-favorite-hidden-features-in-rails-3-2/
Or, if this is more of a view-related decision (i.e. one view will always use the regular _exercises.html.erb and another view would always use e.g. _alternate_exercises.html.erb) then you can specify as such:
<%= render partial: 'alternate_exercises', collection: #exercises, as: :exercise %>
This will render the _alternate_exercises.html.erb partial once for each item in #execrises passing the item in to the partial via a local_assign called exercise.
In this case, I suppose you have two options:
1) Put the conditional code inside of _exercises.html.erb
eg.
<% if #exercise.meets_some_condition %>
you see this stuff
<% else %>
you see other stuff
<% end %>
This way, you can still make use of <%= render #exercises %>
2) Otherwise, your other option is to have separate partials and render them outside.
eg.
<% #exercises.each do |exercise| %>
<% if exercise.meets_some_condition %>
<%= render "exercises/some_condition_exercise" %>
<% else %>
<%= render "exercises/exercise" %>
<% end %>
<% end %>
This is the best approach for rendering partial. You can wrap that partial with if else statement in your code. Here is my example
rendering with form called _victim.html.erb
<%= render :partial => "victim", :locals => {:f => f }%>
rendering without form
<%= render :partial => "victim"%>
I'm trying to render an action in my application.html.erb layout file to display it as a modal box using some jquery scripts. I've heard that i can use render :template => 'spots/new' but it looks like this method is not rendering an action but just a view file.
spots#new
def new
#spot = Spot.new
end
new.html.erb
<%= form_for(#spot) do |f| %>
...
<% end %>
The problem is that when i'm trying to render spots#new with render :template => 'spots/new', i'm getting undefined method 'model_name' for NilClass:Class error. Have you any idea what am i doing wrong ? Thanks in advance
You are correct, render :template => 'spots/new' just renders your view template, it does not call spots#new. You should create #spot instance variable before rendering the template.
In your case probably following code will work:
<% #spot ||= Spot.new %>
<%= form_for(#spot) do |f| %>
...
<% end %>
Here's the call in the application.html.erb file:
<%= render :partial => 'tasks/_new' %>
Here's the partial being rendered (_new.html.erb):
<% form_for #task do |f| -%>
<%= f.text_field :body %>
<%= submit_tag "Submit" %>
<% end -%>
Here's the method in the 'tasks' controller:
def new
#task = Task.new
respond_to do |format|
format.html # new.html.erb
format.xml { render :xml => #task }
end
end
Here's the error message I keep getting:
Missing template tasks/__new.erb in view path app/views
And it says the error is in this line:
<%= link_to "tasks", tasks_path %> <%= render :partial => 'tasks/_new' %>
The file is in the right directory. The weird thing is that there's an
extra _ in the file name, in the error. When I give in and rename the
partial to __new.erb, here's the error I get:
Called id for nil, which would mistakenly be 4 -- if you really wanted the id of nil, use object_id
And it says the error is in this line:
<% form_for #task do |f| -%>
I had also tried without the _ in the code, as Petros suggested, but it returns the same error as above, Called id for nil….
What's going on?
You don't need the _ in your code. It should be:
<%= render :partial => 'tasks/new' %>
The first error is because you don't need to put the _ inside the :partial parameter. Rails takes care of that. That's why you get double __ because Rails will put one for you.
The second error is your real problem. The error suggests that #task is nil. This is true because the partial only knows what the container view knows, and your view in that particular moment hasn't called the action from the proper controller. As you (Baby Diego) already found out and indicated in one of your comments below, you needed to create an instance of a Task in your partial. I don't know if there is a more elegant solution, but maybe someone can suggest something better in the future.
Thanks to MattMcKnight for informing us that the partial itself does only know what the container view knows.
Petros correctly identified the first issue- you don't need the underscore in the partial call.
The second thing to know about partials is that they don't call the controller method, they just reference the view. Thus, you need to setup the #task object in every action that uses that partial, or just call Task.new in the partial. When I have a partial in a layout in similar situations, I usually load it with JavaScript so that I can call the action.
If the partial needs to know about a variable in the calling erb file, you can pass it like this:
<%= render partial: "tasks/new", locals: { task: #task } %>
And in file app/views/tasks/_new.html.erb, refer to the variable like this:
<% form_for task do |f| %>
<%= f.text_field :body %>
<%= submit_tag "Submit" %>
<% end %>
That is, without the #. (The code a: b is just a more convenient form of :a => b.)
I wonder, though, why do you want to use partials in file application.html.erb? I'm assuming that you mean the Ruby-generated file app/views/layouts/application.html.erb, which is supposed to be used as a layout file containing elements common to all your application's pages, not for business logic. Perhaps the file you need to call the partial from is app/views/tasks/index.html.erb?