I've got a controller that gets some data from the database and an html view is rendered nicely in my browser.
Now I need to bootstrap some json in my html (to be used by javascript).
I add the following code to render json in the controller:
#my_json = render_to_string(template: 'dimension_types/index.json.jbuilder')
I do nothing else, just add this code to my controller and what happens is that the browser now just shows my page's html code. In the html source my page is wrapped in <pre></pre> tags.
There's no error in the logs. I tried adding layout: false, passing various combinations of handlers and formats to render -- nothing changes.
What am I doing wrong? What part of the documentation am I missing?
I also came across this problem. There might be a better way to do this, but here is a semi-hack that will work:
# the_controller.rb
def your_action
#...
#json_string = render_to_string(template: 'a_template', formats: [:json])
# reset the content type header
response.headers["Content-Type"] = 'text/html'
#...
end
The next piece of code shows how I made use of the JSON string in my view. If the JSON contains user-generated data, you will want to more thoroughly sanitize it to prevent XSS security risk (more info: https://stackoverflow.com/a/10390313/111635). The JSON I am generating doesn't have this problem, so I just used html_safe:
# the_view.html.erb
# ... bunch of ERB code ...
<%= javascript_tag do %>
$(document).ready(function() {
do_stuff_with_json(<%= #json_string.html_safe %>);
});
<% end %>
Related
So, as I am sure you are all familiar with, you can have actions in Rails that call html.erb files. You can also set up actions to render remotely that call embedded ruby files (for example submitting a "post" form to the "posts" controller, handling it remotely, and calling a js.erb file to update elements in the page).
What I want to know is how to run a js.erb file when I'm running an action that loads a template (html.erb file). To explain, consider if I want to run a User Show page:
class UsersController < ApplicationController
def show
#user = User.find(params[:id])
end
end
Linking to user_path(User.find(1)) will load show.html.erb, and all seems great.
But what if I want to click on a link to user_path(User.find(1)) and load show.html.erb while also loading show.js.erb? If (and I hope it is) this is possible, how could I adapt the show definition to also load show.html.erb and custom_js_file_name.js.erb?
FYI: I'm using Rails 3.0.9 and 3.1.3 on two different applications, and assume that I would put show.js.erb or any others in the Users folder (views/users/...)
By default,
def show
#user = User.find(params[:id])
end
will only render the show view based on if it was requested via HTML, JSON, JS, etc.
I think what you are describing is better suited for the render method in Rails. Typically, controllers use the different format.(:format) methods in the respond blocks to respond to a controller call based on what the request type was (JSON, HTML, JS, etc).
In your show.html.erb file:
<%= render "users/show.js" %>
This allows you to render any arbitrary file you want in another one of your views. This also allows you to split up your large view files into smaller (reusable) pieces called partials (note: all partials are named with a _ character at the beginning and are called via <%= render :partial => "users/my_partial" %> which would render the _my_partial.some_format.erb file)
Try having the show action render the show.js.erb file when requested with a format of js. That should get Rails to render the dynamic template; now link to it from the original show.html.erb with a javascript link tag.
In show.html.erb:
<script type="text/javascript" src="<%= show_users_path(#user.id) -%>.js"></script>
I haven't tried this and the rendering of show.js.erb may put additional formatting that would be a problem.
I've become a bit confused about the idea of "rendering" a "template" due to the way an author speaks about it in a book I'm reading.
My original understanding of "rendering a template" was that it meant that Rails is providing the content that is viewed on the screen/presented to the viewer (in the way that a partial is rendered) but the book I'm reading seems to be using the concept of "rendering a template" to also mean something else. Let me explain in context
This book (rails 3 in action) sets up a page layout using the conventional layouts/application.html.erb file, and then it "yields" to different view pages, such as views/tickets/show.html.erb which adds more content to the screen. that's all straightforward..
Within this view views/tickets/show.html.erb, there is a rendering of a partial (which is also a straightforward concept).
<div id='tags'><%= render #ticket.tags %></div>
Now within this partial there is, using ajax, a call to a "remove" method in the "tags_controller.rb" which is designed to allow authorized users to remove a "tag" from a "ticket" in our mock project management application.
<% if can?(:tag, #ticket.project) || current_user.admin? %>
<%= link_to "x", remove_ticket_tag_path(#ticket, tag),
:remote => true,
:method => :delete,
:html => { :id => "delete-#{tag.name.parameterize}" } %>
<% end %>
Now here is the "remove" action in the tags controller (which disassociates the tag from the ticket in the database)...
def remove
#ticket = Ticket.find(params[:ticket_id])
if can?(:tag, #ticket.project) || current_user.admin?
#tag = Tag.find(params[:id])
#ticket.tags -= [#tag]
#ticket.save
end
end
end
At the end of this remove action, the author originally included render :nothing => true , but then he revised the action because, as he says, "you’re going to get it to render a template." Here's where I get confused
The template that he gets this action to render is "remove.js.erb", which only has one line of jquery inside it, whose purpose is to remove the "tag" from the page (i.e. the tag that the user sees on the screen) now that it has been disassociated from the ticket in the database.
$('#tag-<%= #tag.name.parameterize %>').remove();
When I read "rendering a template" I expect the application to be inserting content into the page, but the template rendered by the "remove" action in the controller only calls a jquery function that removes one element from the page.
If a "template" is "rendered", I'm expecting another template to be removed (in order to make room for the new template), or I'm expecting content to be "rendered" in the way that a partial is rendered. Can you clarify what is actually happening when a "template" is "rendered" in the situation with the jquery in this question? Is it actually putting a new page in front of the user (I expected some sort of physical page to be rendered)
You're nearly there! Rendering a template is indeed always about producing content, but for a slightly wider description of content. It could be a chunk of html, for example an ajax call to get new items might produce some html describing the new items, but it doesn't have to be.
A template might produce javascript as it does in your second example. Personally I am trying to avoid this and instead pass JSON back to the client and let the client side js perform the required work.
Another type of rendering you might perform is to produce some JSON. APIs will often do this, but you might also do this on a normal page. For example rather than rendering some javascript to delete tag x you might render the json
{ to_delete: "tag-123"}
and then have your jQuery success callback use that payload to know which element to remove from the DOM, by having this in your application.js file
$('a.delete_tag').live('ajax:success', function(data){
var selector = '#' + data.to_delete;
$(selector).remove()
}
(Assuming that your delete links had the class 'delete_tag')
Rendering JSON like this isn't really a template at all, since you'd usually do this via
render :json => {:to_delete => "tag-#{#tag.name.parameterize}"}
although I suppose you could use an erb template for this (I can't imagine why though).
My understanding is that js.erb is "rendered" by executing the javascript functions within it. Very often something like the below is done:
jQuery(document).ready(function() {
jQuery('#element').html('<%= escape_javascript(render pages/content) %>');
});
There's a really succinct overview of rendering at http://guides.rubyonrails.org/layouts_and_rendering.html that may help as it also goes into the details of the ActionController::Base#render method and what happens behind the scenes when you use render :nothing (for example). Render but can be used for files or inline code as well -- not just 'templates' in the traditional sense.
I have some html content stored in a database field. I would like trusted admins in our system to be able to edit the HTML when needed. Eventually this html will be converted into an email message and sent to users. In addition to the static html content, the email message has a first and last name that is stored in an active record model.
I was hoping to leave the <%= user.firstname user.lastname %> inside the HTML text when the admins are editing the content and then eventally combine the content with embedded erb the email renderer. I have the part where the admins can save the HTML working fine.
However, even ignoring the email and just trying to render to a normal web page, I am not able to get a view to correctly substitute the embedded <%= ... %> with the information from the database. I always see the <%= ... %> instead of the substituted text. I have tried render_to_string, render :inline, etc.
In summary, I am trying to:
Take some html text with embedded some erb from the database
Run the text through a template where the embedded erb is replaced with the variables passed into locals
Take the resulting text block and either email it to users or display on a web page depending on my needs
The problem is that the results always have the <%= ... %> in it instead of the substitutions.
In an example controller I have:
def showit
#storedhtml = mymodel.savedhtml
#emailtext = render_to_string( template: 'e.html.erb',
layout: false, locals: { user:#user })
end
The e.html.erb contains:
<%= raw #storedhtml %>
and the showit.html.erb has:
= raw #emailtext
I have also tried using inline like this:
def showit
# the line below is substituted but the <p> tags are not converted
#stuff = "<%= '<p>testme</p>' + user.firstname %>"
#storedhtml = mymodel.the_html_content
#output = render( inline: #storedhtml, locals: { user:#user }, layout: true )
end
In a controller you wouldn't use Erb syntax, you'd use normal Ruby string interpolation:
#stuff = "#{'<p>testme</p>'} #{user.firstname}"
# Or, since the HTML isn't dynamic:
#stuff = "<p>testme</p> #{user.firstname}"
And to output it in the view you'd need to use html_safe:
<%= #stuff.html_safe %>
In general, generating HTML directly in the controller isn't a great idea since there are other mechanisms in place, and it creates another place to look when you're trying to figure out what component creates which HTML.
Edit I misunderstood. Another templating engine like Sameera suggested is one option, or just evaluate the DB value as an erb template using your current binding.
You could also create a template resolution component that would allow retrieval directly from the DB if no file is found; the Crafting Rails Applications book discusses this.
I guess what you need is 'liquid' - it's a template language for Rails.
Check this out:
http://liquidmarkup.org/
http://railscasts.com/episodes/118-liquid
Assuming you have a Model with attribute named "template" which returns some html template (with ERB), if you want to render it you can use something like this into your controller's action:
render inline:"<%= raw ERB.new(#your_var.template).result(binding) %>".html_safe, layout:'application'
I'm familiar with using Ajax templates to update particular parts of a page, but how do you render with layout when doing so? For example, given a layout:
#foo
= yield :foo
a simple view "show.html.haml":
= render #bar
and a partial:
- content_for :foo
= bar.to_html
... the HTML result would render within the layout and I'd see my bar content, but say I want to use Ajax to update only the #foo div. I create "show.js.erb":
$("#foo").html("<% escape_javascript(render(#bar)) %>");
But the result is nothing, as my _bar partial is rendered but outside of the layout, thus my :foo content is never yielded to. How do I get the JS template to render inside that layout?
I've found two answers, but I wonder if there's a better way still. These answers are for Rails 3, by the way.
1. Use a separate JS layout.
This is probably the "more correct" way, but unfortunately didn't work for my situation as I'll explain shortly.
What I wasn't fully aware of, is that in a JS request, the lookup formats are set to JS and HTML. Meaning that the controller will render the HTML template if the JS template does not exist.
But it will not look to the HTML layout in the same fashion, meaning the HTML template will be rendered, but the content_for block is never yielded to, leading to an empty response.
So to make the simple example above work out-of-the-box. You'd delete "show.js.erb" and add a JS layout, (e.g. "bars.js.erb") in the lookup path, which would look like this:
$("#foo").html("<% escape_javascript(yield(:foo)) %>");
In this way, the HTML template is rendered, but in the JS layout, and the HTML of #foo is swapped out for the new content of the response.
2. Render the HTML content in the JS response block.
However, #1 this was not an ideal answer for me. My app uses many nested layouts, most of which are very similar. To make the above example work I'd have to create a lot of JS layouts, all of which more or less copies of the original HTML layouts. A waste of time, and not at all DRY. So I came up with this solution.
It feels less ideal than #1, and please tell me if there's a more appropriate way. But this is what I came up with:
# in bars_controller.rb
def show
# ...
respond_to do |format|
format.js do
lookup_context.update_details(:formats => [:html]) do
#content = render_to_string
end
render
end
end
end
In this way I temporarily set the mimetype for the template lookup to be HTML, render the content to a variable, then render the JS template:
// show.js.erb
$("#foo").html("<%= escape_javascript(#content) %>");
There is one further complication to this. In my nested layout setup, in the HTML response, the layout calls the rendering of its parent to continue to build the body, leading to the complete page. In my case, I want it to simply return the body content. So while I don't need JS layouts for this solution, I do need to slightly change my layout, like this:
-# my_layout.html.haml
-# (given a parent layout that yields to :body)
- content_for :body do
= yield(:foo)
- if request.xhr?
= yield(:body)
- else
= render :file => "layouts/my_parent_layout"
In this way the parent is not called on a JS request, simply resulting in the body (up to this point in the nested layout stack).
I saw this code in a Rails controller:
respond_to do |format|
format.js {}
end
I've seen this for XML and HTML formats but not for Javascript.
Is this the way you specify a return format if you use for REST, like if you use replace_html or remote_form_for? I know RJS templates return compiled Javascript so I'm thinking maybe this is where this code might kick in.
If you put code inside the hash symbols(format.js {}), is that what gets send back as javascript to the browser?
It is used when an AJAX request is sent from the browser to a controller. The controller can respond with a script (which is generated by ruby statements in the view) which will be executed on the client.
Rails does a little magic on figuring out what 'template' to send out
in controller:
def foo
end
in view: (app/views/controller/) you can have
foo.html.erb (usual, html template)
foo.rjs (javascript template)
rails will send out the right template back to the browser, HTML for regular requets and RSJ for Ajax requests. You might want to put in javascript code like 'page.replace_html' ..etc in your RJS template. This way, you keep the controller clear of view code.
yuo can always just add the format to the url and see what it responds, /something.js would respond using the format.js code, if you want to use it, you can do the following to avoid rendering your entire layout:
format.js { render :layout => false, :text => #models.to_json }
that would respond with a json string
format.js { render :layout => false }
would require a template called [action].js.erb