In my template files for my Yeoman generator I have if statements to decide whether or not to include some content in the generated files. When the if condition is not satisfied I end up with character returns where the if statement was in the files produced from the template. Is there any way to eliminate these?
It is down to the placement of the if statements this is the way to use them for a list.
<ul>
<li>HTML5 Boilerplate</li><% if (includeJeet) { %>
<li>Jeet</li><% } %><% if (includeRespond) { %>
<li>Respond</li><% } %>
</ul>
If the if statement commences on a new line then the new line is created.
Related
Forgive the vague title, I'm having a hard time figuring out the correct phrase for what I am trying to do.
I have a number of custom snippets I have written to support writing ERB for Ruby on Rails. For this example, I am trying to use an if tag that can be on a single line:
<% if something %>Content Here<% end %>
or multiple lines with indented content:
<% if something %>
Content Here
<% end %>
I am able to get the first (single line) format working fine with the following snippet:
<![CDATA[<% if $1 %>${2:$SELECTION}<% end %>$0]]>
The problem is that if I type in the trigger, hit tab, type in the conditional for $1, hit tab, then hit return, Sublime does exactly what I type and puts the following:
<% if something %>
[cursor]<% end %>
Is there a way in the snippet to instead treat the if and end tags like HTML tags:
<% if something %>
[cursor]
<% end %>
Thanks!
The easiest way is to define a new snippet with a new tabTrigger. It will look something like:
<snippet>
<content><![CDATA[<% if $1 %>
${2:$SELECTION}
<% end %>$0]]>
</content>
Sometimes it's more convenient to print in <%%>. How to do it in Rails?
http://api.rubyonrails.org/classes/ActionView/Helpers/TextHelper.html#method-i-concat
Should be what you are looking for.
E.g. the following statement using concat:
<% concat "Output" %>
is equivalent to:
<%= "Output" %>
In ERB:
The <% %> signify that there is Ruby code here to be interpreted.
The <%= %> says output the ruby code, ie display/print the result.
So it seems you need to use the extra = sign if you want to output in a standard ERB file.
Otherwise, you could look at alternatives to ERB which require less syntax,.. maybe try something like HAML. http://haml-lang.com/tutorial.html
Example:
# ERB
<strong><%= item.title %></strong>
# HAML
%strong= item.title
Is that more convenient?
erb has two method to evaluate inline ruby expressions. The <% which evaluates the expression and the <%= which evaluates and prints. There is no global object to print to within the binding context.
As mentioned by Omar, there is a concat method, which is part of ActionView. This will do what you want.
Unlike a scripting language escape, there is no default output for erb. Since erb is simply a function, and given a template and binding will return a variable, it returns the values of text and functions recursively.
There is hot debate as to how much logic should be allowed in a view, but as little as possible is what most people aim for. If you are putting more code than text in the view, you may want to consider refactoring your code.
I am working on a style guide which displays the code, as well as the output. It is currently structured so that the code only needs to be described once, and is displayed in both its raw and interpreted versions, like so:
<% code = <<PLACE_THE_EXAMPLE_CODE_BETWEEN_THESE_TWO_LINES_EXACTLY_AS_YOU_WANT_IT_TO_APPEAR
<div>
#{ image_tag 'image.png' }
</div>
PLACE_THE_EXAMPLE_CODE_BETWEEN_THESE_TWO_LINES_EXACTLY_AS_YOU_WANT_IT_TO_APPEAR
%>
<%= raw code %>
<%= content_tag :pre, code, class: "prettyprint linenums" %>
This is great, and fairly easy to maintain. The problem comes in with the rails helpers, like image_tag in the above example. The view example correctly displays an image in a div, and the code example displays the relevant HTML. In this case, the relevant HTML includes an anchor tag - the results of the image_tag method, not the call itself.
I would prefer the code examples to display the helper methods, rather that their results. I am able to make this work by specifying the example code in a file, and either rendering or reading the file. I would prefer to make this work by specifying the code in a variable, as above, but I can't seem to get an ERB delimiter to work inside of a string inside of an erb block. Even the simplest case of <% foo = '<%= bar %>' %> doesn't work at all. I've tried playing with the syntax (<%% %%> and % % for example), using details from the official documentation, without much success.
The only information I could find on the matter is here, using <%= "<" + "%=" %> link_to <%= image.css_tag.humanize %> <%= "%" + ">" %> %>, which does not work in this use case (if at all).
So, is there a way to specify a string that contains a ERB end-delimiter (%>) in an ERB string, or am I stuck using the slightly clunkier file-read method? Thanks!
Edit:
What I would like to end up with is a working version of this:
<%# Idealized code - does not work %>
<% code = <<PLACE_THE_EXAMPLE_CODE_BETWEEN_THESE_TWO_LINES_EXACTLY_AS_YOU_WANT_IT_TO_APPEAR
<div>
<% image_tag 'image.png' %>
</div>
PLACE_THE_EXAMPLE_CODE_BETWEEN_THESE_TWO_LINES_EXACTLY_AS_YOU_WANT_IT_TO_APPEAR
%>
So that <%= raw code %> would (continue to) output:
<div>
<img src="/images/image.png" alt="Image" />
</div>
And <%= content_tag :pre, code, class: "prettyprint linenums" %> would output:
<pre class="prettyprint linenums">
<div>
<% image_tag 'image.png' %>
</div>
</pre>
Instead of what it currently does when using a variable, which is:
<pre class="prettyprint linenums">
<div>
<img src="/images/image.png" alt="Image" />
</div>
</pre>
I want users to be able to copy the code example and paste it into a new view, without having to translate HTML back into the helpers that produce them. I think what I basically need is an alternative ERB delimiter, in the same way that ' and " (or even %q{}) vary for strings. It seems that even though the final ERB delimiter is occurring inside of a string, it is being actually processed as the end of the block. The simplest case of <% foo = '<%= bar %>' %> demonstrates somewhat what I want to accomplish. In a generator, you might use <% foo = '<%%= bar %>' %> (or something similar), to tell it not to process as ERB right then and there. This all works fine when reading from a file, or even in a pure rb file (like a helper), but it makes the most sense to put it in the view, in this case, as it is intended to be easily manipulated by our designers.
If I'm understanding you right, your real problem is that heredocs behave like double quotes as far as interpolation is concerned. So all you need is a quoting mechanism that behaves like single quotes. Ruby has lots of string quoting mechanisms, in particular we have %q{...}:
<% code = %q{
<div>
#{ image_tag 'image.png' }
</div>
} %>
You can use other delimiters if you'd like: %q|...|, %q(...), etc. There's still a change of course but at least you don't have to worry about interpolation problems.
If you really want to use a heredoc, you can specify the heredoc terminator with quotes and the corresponding quoting style will apply to the content:
<% code = <<'PLACE_THE_EXAMPLE_CODE_BETWEEN_THESE_TWO_LINES_EXACTLY_AS_YOU_WANT_IT_TO_APPEAR'
<div>
#{ image_tag 'image.png' }
</div>
PLACE_THE_EXAMPLE_CODE_BETWEEN_THESE_TWO_LINES_EXACTLY_AS_YOU_WANT_IT_TO_APPEAR
%>
The single quotes in <<'PLACE...' specify that single quoting rules (i.e. no interpolation) apply to the heredoc's content.
Of course none of that stuff will work with embedded ERB like this:
<% code = %q{
<div>
<% ... %>
</div>
} %>
because the ERB parser will see the first %> as the closing delimiter for the outer <% code... part. Fear not, I think I have a plan that will work without involving gross hacks or too much work.
Some preliminaries:
Rails uses Erubis for ERB processing.
Erubis allows you to change the delimiters with the :pattern option to its constructor.
Rails uses Tilt and Sprockets to handle the template processing pipeline, these allow you to make the right things happen to pancakes.js.coffee.erb in the right order.
Using the above you can add your own template format that is ERB with a different delimiter and you can have Rails use this new format to handle your "special" sections before the normal ERB processing can make a mess of things.
First you need to hook up Tilt. If you have a look at lib/tilt/erb.rb in your Tilt installation, you'll see the Erubis stuff in Tilt::ErubisTemplate at the bottom. You should be able to subclass Tilt::ErubisTemplate and provide a prepare override that adds, say, a :pattern => '<!--% %-->' option and punts to the superclass. Then register this with Tilt and Sprockets in a Rails initializer with something like this:
Tilt.register(Your::Template::Subclass, 'klerb') # "kl" for "kludge" :)
Rails.application.assets.register_engine('.klerb', Your::Template::Subclass)
Now your application should be able to handle .klerb files with <!--% ... %--> as the template delimiters. And you can also chain your klerb with erb using names like pancakes.html.erb.klerb and the file will go through klerb before the ERB; this means that templates like this (in a file called whatever.html.erb.klerb):
<!--% code = <<PLACE_THE_EXAMPLE_CODE_BETWEEN_THESE_TWO_LINES_EXACTLY_AS_YOU_WANT_IT_TO_APPEAR
<div>
<% image_tag 'image.png' %>
</div>
PLACE_THE_EXAMPLE_CODE_BETWEEN_THESE_TWO_LINES_EXACTLY_AS_YOU_WANT_IT_TO_APPEAR
%-->
<!--%= "code = escape_the_erb_as_needed(%q{#{code}})" %-->
<% do_normal_erb_stuff %>
will do The Right Thing.
You'd need a helper to implement the escape_the_erb_as_needed functionality of course; a little experimentation should help you sort out what needs to be escape and in what way.
All that might look a bit complicated but it is really pretty straight forward. I've added custom template processing steps using Tilt and Sprockets and it turned out to be pretty simple in the end; figuring out which simple things to do took some work but I've already done that work for you:
Tilt::Template subclass, you get this by piggy backing on Tilt::ErubisTemplate.
Register with Tilt by calling Tilt.register.
Register with Sprockets by calling Rails.application.assets.register_engine.
...
Profit.
Is there any standard or emerging standard to document the parameters that can be passed into a Rails partial ?
When _my_partial.html.erb expects a title and an elements local var passed with render 'my_partial', title: t, elements: e, there must be a common way to document their names, expected types and roles, without reading the whole partial code. Something like RDoc or Tomdoc for methods and classes. Isn't there ?
Edit: I've found a post whose author advocates initializing parameters with <% var ||= 'default_val' %> in the first lines of the partial, which is indeed a safe practice and a kind of in-code doc. Is there really no comment/parameter-declaration solution for this ?
At the beginning of your partial, simply call all the variables that are referenced.
# _my_partial.html.erb
<% title %> <--- first line of file
<% elements[0] %>
<h3><%= title %></h3>
<% elements.each do |element| %>
<p> etc ... </p>
Reasons why this is good for your project:
it does not rely on comments or non-code files
any developer on the project can quickly find out which variables are needed by looking at the top of the file in question
by calling the variables, you ensure that a missing variable will result in an exception.
elements is called with square brackets because we also want it to blow up if it's not an enumerable, right?
The practice of using <% var ||= 'default_val' %> is actually unsafe because it allows bugs to hide. You want your code to immediately blow up the moment something isn't done right. And if these variables should be passed, then you want the code to blow up when they're not there.
Sometimes it's more convenient to print in <%%>. How to do it in Rails?
http://api.rubyonrails.org/classes/ActionView/Helpers/TextHelper.html#method-i-concat
Should be what you are looking for.
E.g. the following statement using concat:
<% concat "Output" %>
is equivalent to:
<%= "Output" %>
In ERB:
The <% %> signify that there is Ruby code here to be interpreted.
The <%= %> says output the ruby code, ie display/print the result.
So it seems you need to use the extra = sign if you want to output in a standard ERB file.
Otherwise, you could look at alternatives to ERB which require less syntax,.. maybe try something like HAML. http://haml-lang.com/tutorial.html
Example:
# ERB
<strong><%= item.title %></strong>
# HAML
%strong= item.title
Is that more convenient?
erb has two method to evaluate inline ruby expressions. The <% which evaluates the expression and the <%= which evaluates and prints. There is no global object to print to within the binding context.
As mentioned by Omar, there is a concat method, which is part of ActionView. This will do what you want.
Unlike a scripting language escape, there is no default output for erb. Since erb is simply a function, and given a template and binding will return a variable, it returns the values of text and functions recursively.
There is hot debate as to how much logic should be allowed in a view, but as little as possible is what most people aim for. If you are putting more code than text in the view, you may want to consider refactoring your code.