`&lt;%==` is equivalent to `raw`.

From the [Ruby on Rails Guide](http://edgeguides.rubyonrails.org/active_support_core_extensions.html#output-safety):

&gt; To insert something verbatim use the `raw` helper rather than calling
&gt; `html_safe`:
&gt; 
&gt;     &lt;%= raw @cms.current_template %&gt; &lt;%# inserts @cms.current_template as is %&gt;
&gt; 
&gt; or, equivalently, use `&lt;%==`:
&gt; 
&gt;     &lt;%== @cms.current_template %&gt; &lt;%# inserts @cms.current_template as is %&gt;


Rails actually uses [Erubis](http://www.kuwata-lab.com/erubis/) instead of ERB, which supports a variety of other stuff.

`&lt;%==` is exactly as you expect, though: [It emits the value unescaped](http://www.kuwata-lab.com/erubis/users-guide.03.html#escape-enhancer)

When I tried to install mongoDb in my AWS EC2 Linux instance:Ubuntu 12.04.1 LTS,

    deb http://downloads-distro.mongodb.org/repo/ubuntu-upstart dist 10gen

I get this following error, meaning deb command is not found.
```
$ deb Sorry, command-not-found has crashed! Please file a bug report
at: https://bugs.launchpad.net/command-not-found/+filebug Please
include the following information with the report:
 
command-not-found version: 0.2.44
```
Can someone please help me find out how to install deb in my AWS instance?

AWS EC2 Ubuntu 12.04.1 LTS: deb command-not-found

In Google Chrome, how you can check which files are served from the browser cache, and which comes from the server?

Check whether network response is coming from server or Chrome cache

I saw this recently, thought it was interesting.  But I don&#39;t really understand what it does?

Ex.  I have a rails app and I want to bootstrap some json, so that I don&#39;t have to make a second request.  Normally I would write something like this.

`&lt;%= raw @model.to_json %&gt;`
or
`&lt;%= @model.to_json.html_safe %&gt;`

I have to send the message `raw` or `html_safe` or the json will be html escaped and thus not parsed correctly.  However, this seems to work too.

`&lt;%== @model.to_json %&gt;`

But I can&#39;t find any documentation.

Does anyone know what this does exactly?  i.e.  Is it the exact same as calling `html_safe` or `raw`?  Or is there more to it?

What does &lt;%== %&gt; do in rails erb?

I saw this recently, thought it was interesting. But I don't really understand what it does?
Ex. I have a rails app and I want to bootstrap some json, so that I don't have to make a second request. Normally I would write something like this.
<code>&#x3C;%= raw @model.to_json %></code>
or
<code>&#x3C;%= @model.to_json.html_safe %></code>
I have to send the message <code>raw</code> or <code>html_safe</code> or the json will be html escaped and thus not parsed correctly. However, this seems to work too.
<code>&#x3C;%== @model.to_json %></code>
But I can't find any documentation.
Does anyone know what this does exactly? i.e. Is it the exact same as calling <code>html_safe</code> or <code>raw</code>? Or is there more to it?

`form_for` seems to ignore any &#39;extra&#39; attributes like a `data-foo` attribute or `class` passed as `options` in its second argument.

    = form_for @user, {:url =&gt; &#39;foo&#39;, :class =&gt; &#39;x&#39;, &#39;data-bar&#39; =&gt; &#39;baz&#39; } do |f|
      # ...

The output is a `&lt;form&gt;` tag with no `x` class or `data-bar` attribute.

What’s the fix?

Or, how can I grab a `FormBuilder` instance without using `form_for`?

Use Rails’ form_for but set custom classes, attributes on &lt;form&gt; element?

I have created an app in Rails on Heroku using a PostgreSQL database.

It has a couple of tables designed to be able to sync with mobile devices where data can be created on different places. Therefor I have a uuid field that is a string storing a GUID in addition to an auto increment primary key. The uuid is the one that is communicated between the server and the clients.

I realised after implementing the sync engine on the server side that this leads to performance issues when needing to map between uuid&lt;-&gt;id all the time (when writing objects, I need to query for the uuid to get the id before saving and the opposite when sending back data).

I&#39;m now thinking about switching to only using UUID as primary key making the writing and reading much simpler and faster.

I&#39;ve read that UUID as primary key can sometimes give bad index performance (index fragmentation) when using clustered primary key index. Does PostgreSQL suffer from this problem or is it OK to use UUID as primary key?

I already have a UUID column today so storage wise it will be better because I drop the regular id column.



Will UUID as primary key in PostgreSQL give bad index performance?

I would like to give visitors the option to download some pdf. 
I have tried:

    &lt;%= link_to &quot;abc&quot;, &quot;/data/abc.pdf&quot;%&gt;
    
    &lt;%= link_to &quot;abc&quot;, &quot;/data/abc.pdf&quot;, :format =&gt; &#39;pdf&#39; %&gt;

and some variations but they don&#39;t seem to work. I keep getting `No route matches [GET] &quot;/data/abc.pdf&quot;`

I have the pdf files in a folder called data, located in the assets folder.
Any help would be appreciated.

file download link in rails

I have this testingdatabase which, by now, is stuffed with junk. Now I&#39;ve done a few Table.destroy_all commands in the rails console which deletes all records and dependencies which is awesome. However; I&#39;d like to truncate everything so the ID&#39;s etc. start at 1 again. Is there any way in Rails 3?

Truncate table(s) with rails console

I want to make sure I&#39;m using them for the correct occasion and want to know of any subtleties.  They seem to function the same way, which is to check to see if a object field has been defined, when I use them via the console and there isn&#39;t a whole lot information online when I did a google search. Thanks!

What is the difference between using .exists?, and .present? in Ruby?

I have this `jQuery` function that returns the current time as the number of milliseconds since the epoch (Jan 1, 1970):

    time = new Date().getTime();

Is there a way to do the same in Ruby?

Right now, I am using Ruby&#39;s `Time.now.to_i` which works great but returns a **10-digit** integer (number of seconds)

How can I get it to display the number of milliseconds, as in `jQuery`?

How to get the current time as 13-digit integer in Ruby?

What command opens Ruby&#39;s REPL?

In Python, you simply open `python` without any arguments.

What command opens Ruby&#39;s REPL?

In Ruby, is there a way to &#39;override&#39; a constant in a subclass in such a way that calling an inherited method from the subclass results in that method using the new constant instead of the old one? For example:

    class SuperClass
      CONST = &quot;Hello, world!&quot;
      def self.say_hello
        CONST
      end
    end
    
    class SubClass &lt; SuperClass
      override_const :CONST, &quot;Hello, Bob!&quot;
    end
    
    SuperClass.say_hello # =&gt; &quot;Hello, world!&quot;
    SubClass.say_hello   # =&gt; &quot;Hello, Bob!&quot;

If not, is there perhaps a way to do something like this instead?

    class SuperClass
      CONST = &quot;Hello, world!&quot;
      def self.say_hello
        CONST
      end
    end

    SubClass = SuperClass.clone
    SubClass.send(:remove_const, :CONST)
    SubClass.const_set(:CONST, &quot;Hello, Bob!&quot;)
    
    SubClass.say_hello # =&gt; &quot;Hello, Bob!&quot;

----------

Note: I tried my second example out in irb, and it seems to work except that class methods can&#39;t seem to access CONST after I clone the class:

    irb(main):012:0&gt; SubClass.say_hello
    NameError: uninitialized constant Class::CONST
            from (irb):4:in `say_hello&#39;
            from (irb):12
            from C:/Ruby193/bin/irb:12:in `&lt;main&gt;&#39;

Override ruby constant in subclass so inherited methods use new constant instead of the old?

I have a link that I need to submit a post request with. Normally, I&#39;d use jQuery and prevent the link&#39;s default behavior and then submit a form to the destination. This seems like something Rails should be able to help me out with. Sure enough, the `link_to` method has an option for specifying a POST http method:

    link_to &quot;Profile&quot;, &#39;http://example.com/profile&#39;, method: :post

That works, but I need to add 2 parameters too. I tried:

    link_to &quot;Profile&quot;, &#39;http://example.com/profile&#39;, method: post, param1: &#39;value1&#39;, param2: &#39;value2&#39;

That just added those parameters to the `&lt;a&gt;` HTML element, but didn&#39;t submit those when clicking the link:

    &lt;a rel=&quot;nofollow&quot; param1=&quot;value1&quot; param2=&quot;value2&quot; data-method=&quot;post&quot; href=&quot;http://example.com/profile&quot;&gt;Profile&lt;/a&gt;

Is there a way to do a POST request with parameters using `link_to` or any other Rails method? I&#39;m using Rails 3.2.9.

Using Rails link_to for links that post

I have some Ruby methods certain (or all) controllers need. I tried putting them in `/app/helpers/application_helper.rb`. I&#39;ve used that for methods to be used in views. But controllers don&#39;t see those methods. Is there another place I should put them or do I need to access those helper methods differently?

Using latest stable Rails.

Where to put Ruby helper methods for Rails controllers?

**im trying to do default value for input**

works ok:

    &lt;%= f.input_field :quantity, default: &#39;1&#39; %&gt; 

but i need f.input not f.input_field

    &lt;%= f.input :quantity %&gt; 

&lt;br /&gt;


- im trying it with standard html value - but after unsucessfull validation quantity is overriden by 1 - undesired

        &lt;%= f.input :quantity, input_html: {value: &#39;1&#39;} %&gt;


- when i remove value and validation is unsucessfull quantity is populated - everything is ok

        &lt;%= f.input :quantity %&gt;

**how to solve this ? 
is there any alternative like in f.input_field - :default ?
or there is any other solution with value ?** 

Content Type	Original Author	Original Content on Stackoverflow
Question	mwoods79	View Question on Stackoverflow
Solution 1 - Ruby on-Rails	Stefan	View Answer on Stackoverflow
Solution 2 - Ruby on-Rails	Nevir	View Answer on Stackoverflow

What does <%== %> do in rails erb?

Ruby on-Rails Problem Overview

Ruby on-Rails Solutions

Solution 1 - Ruby on-Rails

Solution 2 - Ruby on-Rails

Check whether network response is coming from server or Chrome cache

AWS EC2 Ubuntu 12.04.1 LTS: deb command-not-found

Attributions