Remember to restart your rails server after installing and configuring devise.

If you have the Devise gem specified in the Gemfile, just make sure you have the following in your routes.rb file:

     devise_for :users

Also, here&#39;s a trick to make sure Devise is mapped properly, run: rails c, (the Rails app console) in your app&#39;s folder and then the following command line:

     Devise.mappings.keys

You should see:

    =&gt; [:user] 


Cheers!


Honestly, I would recommend following these two Railscasts ([Episode 209][1] and [Episode 210][2]). The first is a simple and very easy walkthrough for installing Devise and the second is about customizing it to fit your application. 

I&#39;ve watched both episodes and they drastically helped me with Devise, particularly with the customization. 

Your best bet is to start from scratch - you&#39;ll learn a heck of a lot and have Devise fully installed and functional.

Hope this helps! Good luck.


  [1]: http://railscasts.com/episodes/209-introducing-devise
  [2]: http://railscasts.com/episodes/210-customizing-devise



You may need to do a &lt;code&gt;bundle install&lt;/code&gt;

I&#39;m embedding a large array in `&lt;script&gt;` tags in my HTML, like this (nothing surprising):

    &lt;script&gt;
    	var largeArray = [/* lots of stuff in here */];
    &lt;/script&gt;
    
In this particular example, the array has 210,000 elements. That&#39;s well below the theoretical maximum of 2&lt;sup&gt;31&lt;/sup&gt; - by **4 orders of magnitude**. Here&#39;s the fun part: if I save JS source for the array to a file, that file is &gt;44 megabytes (46,573,399 bytes, to be exact).

If you want to see for yourself, you can [download it from GitHub](https://github.com/downloads/mjball/Stack-Overflow-Q-A/largeArray.js.zip). (All the data in there is canned, so much of it is repeated. This will not be the case in production.)

Now, I&#39;m really not concerned about _serving_ that much data. My server gzips its responses, so it really doesn&#39;t take all that long to get the data over the wire. However, there is a really nasty tendency for the page, once loaded, to **crash** the browser. I&#39;m not testing at all in IE (this is an internal tool). My primary targets are Chrome 8 and Firefox 3.6.

In Firefox, I can see a reasonably useful error in the console:

&gt; **`Error: script stack space quota is exhausted`**

In Chrome, I simply get the sad-tab page:

![enter image description here][1]

## Cut to the chase, already ##

- Is this _really_ too much data for our modern, &quot;high-performance&quot; browsers to handle?
- Is there anything I can do* to gracefully handle this much data?

Incidentally, I was able to get this to work (read: not crash the tab) on-and-off in Chrome. I really thought that Chrome, at least, was made of tougher stuff, but apparently I was wrong...


  [1]: http://i.stack.imgur.com/QsHwD.png
  
----------------------

## Edit 1 ##

@Crayon: I wasn&#39;t looking to justify _why_ I&#39;d like to dump this much data into the browser at once. Short version: either I solve this one (admittedly not-that-easy) problem, or I have to solve a whole slew of other problems. I&#39;m opting for the simpler approach for now.

@various: right now, I&#39;m not especially looking for ways to actually reduce the number of elements in the array. I know I could implement Ajax paging or what-have-you, but that introduces its own set of problems for me in other regards.

@Phrogz: each element looks something like this:

    {dateTime:new Date(1296176400000),
     terminalId:&#39;terminal999&#39;,
     &#39;General___BuildVersion&#39;:&#39;10.05a_V110119_Beta&#39;,
     &#39;SSM___ExtId&#39;:26680,
     &#39;MD_CDMA_NETLOADER_NO_BCAST___Valid&#39;:&#39;false&#39;,
     &#39;MD_CDMA_NETLOADER_NO_BCAST___PngAttempt&#39;:0}
     
@Will: but I have a computer with a 4-core processor, 6 gigabytes of RAM, over half a terabyte of disk space ...and I&#39;m not even asking for the browser to do this quickly - I&#39;m just asking for it to work _at all!_ ☹

----------------------

## Edit 2 ##

**Mission accomplished!**

With the spot-on suggestions from [Juan](https://stackoverflow.com/questions/4833480/is-this-asking-too-much-of-a-browser/4833756#4833756) as well as [Guffa](https://stackoverflow.com/questions/4833480/is-this-asking-too-much-of-a-browser/4833631#4833631), I was able to get this to work! It would appear that the problem was just in _parsing_ the source code, not actually working with it in memory.

To summarize the comment quagmire on Juan&#39;s answer: I had to split up my big array into a series of smaller ones, and then `Array#concat()` them, but that wasn&#39;t enough. I **also** had to put them into separate `var` statements. Like this:

    var arr0 = [...];
    var arr1 = [...];
    var arr2 = [...];
    /* ... */
    var bigArray = arr0.concat(arr1, arr2, ...);
    
To everyone who contributed to solving this: **thank you.** The first round is on me!
  
----------------------
  
&lt;sub&gt;*other than the obvious: sending less data to the browser&lt;/sub&gt;

Have I reached the limits of the size of objects JavaScript in my browser can handle?

Can some one explain the conceptual difference between both of them. Read somewhere that the second one creates a new array by destroying all references to the existing array and the .length=0 just empties the array. But it didn&#39;t work in my case

    //Declaration 
    var arr = new Array();

The below one is the looping code that executes again and again.

    $(&quot;#dummy&quot;).load(&quot;something.php&quot;,function(){
       arr.length =0;// expected to empty the array
       $(&quot;div&quot;).each(function(){
           arr = arr + $(this).html();
       });
    });

But if I replace the code with `arr =[]` in place of `arr.length=0` it works fine. Can anyone explain what&#39;s happening here.

Difference between Array.length = 0 and Array =[]?

After I install devise and create a user model. I `rake db:migrate` and then I `rake routes`.  I then get a error with &quot;undefined method `devise_for&#39; for  #&lt;ActionDispatch::Routing::Mapper:0x1053b93d0&gt;&quot;.  What could be causing this error?

    

undefined method `devise_for&#39; in rails

<p>After I install devise and create a user model. I <code>rake db:migrate</code> and then I <code>rake routes</code>.  I then get a error with "undefined method `devise_for' for  #<actiondispatch::routing::mapper:0x1053b93d0>".  What could be causing this error?</actiondispatch::routing::mapper:0x1053b93d0></p>


So I have this loop:

    &lt;% @images.each do |page| %&gt;

    &lt;% end %&gt;

How would I get the index of &quot;page&quot; inside of the loop?

Rails get index of &quot;each&quot; loop

Often I need to check if some value is blank and write that &quot;No data present&quot; like that:

    @user.address.blank? ? &quot;We don&#39;t know user&#39;s address&quot; : @user.address

And when we have got about 20-30 fields that we need to process this way it becomes ugly.

What I&#39;ve made is extended String class with `or` method

    class String
      def or(what)
        self.strip.blank? ? what : self
      end
    end

    @user.address.or(&quot;We don&#39;t know user&#39;s address&quot;)

Now it is looking better. But it is still raw and rough

How it would be better to solve my problem. Maybe it would be better to extend `ActiveSupport class` or use helper method or mixins or anything else. What ruby idealogy, your experience and best practices can tell to me.

If string is empty then return some default value

I have seen a lot usage of double colons in Rails before class names.

For example:

    require ::File.expand_path(&#39;../config/environment&#39;,  __FILE__)

I know what `Module::Class::Constant` means, but `::Class` ?

Double colons before class names in Ruby?

How can I get the current session id in rails 3?

I&#39;ve tried the following with no luck:

    session[:session_id]
    session[&#39;session_id&#39;]
    session[:id]
    session[&#39;id&#39;]
    session.id
    session.session_id

Finding the session id in rails 3

I tried using `gem install pg` but it doesn&#39;t seem to work.

`gem install pg` gives this error

    Temporarily enhancing PATH to include DevKit...
    Building native extensions.  This could take a while...
    ERROR:  Error installing pg:
            ERROR: Failed to build gem native extension.
    
    C:/Ruby/bin/ruby.exe extconf.rb
    checking for pg_config... no
    No pg_config... trying anyway. If building fails, please try again with
     --with-pg-config=/path/to/pg_config
    checking for libpq-fe.h... no
    Can&#39;t find the &#39;libpq-fe.h header
    *** extconf.rb failed ***
    Could not create Makefile due to some reason, probably lack of
    necessary libraries and/or headers.  Check the mkmf.log file for more
    details.  You may need configuration options.
    
    Provided configuration options:
            --with-opt-dir
            --without-opt-dir
            --with-opt-include
            --without-opt-include=${opt-dir}/include
            --with-opt-lib
            --without-opt-lib=${opt-dir}/lib
            --with-make-prog
            --without-make-prog
            --srcdir=.
            --curdir
            --ruby=C:/Ruby/bin/ruby
            --with-pg
            --without-pg
            --with-pg-dir
            --without-pg-dir
            --with-pg-include
            --without-pg-include=${pg-dir}/include
            --with-pg-lib
            --without-pg-lib=${pg-dir}/lib
            --with-pg-config
            --without-pg-config
            --with-pg_config
            --without-pg_config
    
    
    Gem files will remain installed in C:/Ruby/lib/ruby/gems/1.8/gems/pg-0.10.1 for
    inspection.
    Results logged to C:/Ruby/lib/ruby/gems/1.8/gems/pg-0.10.1/ext/gem_make.out



unable to install pg gem

Can I define an abstract class without adding an abstract method?

Defining an abstract class without any abstract methods

I have a method inside of a method. The interior method depends on a variable loop that is being run. Is that a bad idea?

Is it possible to have Methods inside Methods?

When do I use `@see` when dealing with JavaDocs? What is its usage?

For example if `MethodA` calls `MethodB` then do I have to put `@see` in `MethodB`&#39;s javadoc and reference `MethodA` because that is what called it, or do I have to put a reference to `MethodB` from `MethodA` because it&#39;s calling it. I&#39;ve read the stuff about `@see` on the Oracle website and it seems to me to be incredibly vague, it says it means &quot;see also&quot; but not really what that means!

Usage of @see in JavaDoc?

Using dynamic pattern perhaps? You can call any method/property using the dynamic keyword, right? How to check whether the method exist before calling myDynamicObject.DoStuff(), for example?

How to check whether an object has certain method/property?

Question:

    package GoodQuestions;
    public class MyClass {	
    	MyClass() throws CloneNotSupportedException {
    		try {
    			throw new CloneNotSupportedException();
    		} catch(Exception e) {
    			e.printStackTrace();
    		}
    	}	
    
    	public static void main(String[] args) {	
    		try {
    			MyClass  obj = new MyClass();
    			MyClass obj3 = (MyClass)obj.clone();			
    		} catch (CloneNotSupportedException e) {
    			e.printStackTrace();
    		}
    	}
    }

Here class &#39;MyClass&#39; can able to clone its own object by calling the clone method in &#39;Object&#39; class.
When I try to clone the of this class(&#39;MyClass&#39;) in another class(&#39;TestSingleTon&#39;) in the same package &#39;GoodQuestions&#39; it is throwing the following compile time error.

***&#39;The method clone() from the type Object is not visible***&#39;

So here is the code it throwing the above error?

    package GoodQuestions;
    public class TestSingleTon {
    	public static void main(String[] args) {
    		MyClass  obj = new MyClass();
    		MyClass obj3 = obj.clone(); ---&gt; here is the compile error.
    	}
    }

The method clone() from object is not visible?

My sessions with devise timeout after 1-3 hours of non-use (not sure exactly how long). How can I adjust this?

I&#39;ve looked over the docs and can&#39;t seem to find a setting for this.

Setting session length with Devise

After loading the Rails console, how should I sign in a user?

Devise provides a test helper which can be used in tests and I&#39;ve tried to use in console:

    &gt;&gt; include Devise::TestHelpers
    &gt;&gt; helper.sign_in(User.first)

But I get:

    NoMethodError: undefined method `env&#39; for nil:NilClass

Anyway, I would like to use the real devise helper and not this test helper. Is there any way to achieve this?

How to sign in a user using Devise from a Rails console?

I am using the following code for my routes:

    devise_for :user, 
      :as =&gt; &#39;&#39;, 
      :path_names =&gt; { 
        :sign_in =&gt; &quot;&quot;, 
        :sign_out =&gt; &quot;logout&quot;, 
        :sign_up =&gt; &quot;register&quot; 
      }
But when I&#39;m logged out and I goto `/logout` I get the following error:

&gt; No route matches {:action=&gt;&quot;new&quot;,
&gt; :controller=&gt;&quot;devise/sessions&quot;}

How do I setup the root path to be to `:sign_in` action?

Setting Devise Login to be root page

I&#39;m trying to use a different/custom layout named &quot;devise&quot; for the sign_in action. I found [this](https://github.com/plataformatec/devise/wiki/How-To:-Create-custom-layouts) page in the devise wiki, and the second example even says you can do it per-action (in this case, `sign_in` action), but it shows no example of doing that. Someone on IRC told me I could try this:

    class ApplicationController &lt; ActionController::Base
      protect_from_forgery

      layout :layout_by_resource

      def layout_by_resource
        if devise_controller? &amp;&amp; resource_name == :user &amp;&amp; action_name == &#39;sign_in&#39;
          &quot;devise&quot;
        else
          &quot;application&quot;
        end
      end
    end

But it does not seem to be working as it&#39;s still loading the default application layout. I would appreciate any help.

different layout for sign_in action in devise

I want to update users attributes without password in devise. The case is like, if password and password confirmation fields are not blank then I need devise error and if they are blank then other user attributes need to be updated. How could I do this with devise?

Thanks in advance! 

Devise update user without password

I want to know what the difference is between `null` and `undefined` in JavaScript.

What is the difference between null and undefined in JavaScript?

1. How do I check a variable if it&#39;s `null` or `undefined` and what is the difference between the `null` and `undefined`?

2. What is the difference between `==` and `===` (it&#39;s hard to search Google for &quot;===&quot; )?


JavaScript checking for null vs. undefined and difference between == and ===

Which method of checking if a variable has been initialized is better/correct?
(Assuming the variable could hold anything (string, int, object, function, etc.))

    if (elem) { // or !elem
or
    
    if (typeof elem !== &#39;undefined&#39;) {
or
    
    if (elem != null) {

JavaScript check if variable exists (is defined/initialized)

I know that I can test for a JavaScript variable and then define it if it is `undefined`, but is there not some way of saying

```js
var setVariable = localStorage.getItem(&#39;value&#39;) || 0;
```

seems like a much clearer way, and I&#39;m pretty sure I&#39;ve seen this in other languages. 

Set a variable if undefined in JavaScript

Is there a universal JavaScript function that checks that a variable has a value and ensures that it&#39;s not `undefined` or `null`? I&#39;ve got this code, but I&#39;m not sure if it covers all cases:

    function isEmpty(val){
        return (val === undefined || val == null || val.length &lt;= 0) ? true : false;
    }

Content Type	Original Author	Original Content on Stackoverflow
Question	Yeddie	View Question on Stackoverflow
Solution 1 - Ruby on-Rails	Serge Paquet	View Answer on Stackoverflow
Solution 2 - Ruby on-Rails	Florin	View Answer on Stackoverflow
Solution 3 - Ruby on-Rails	vich	View Answer on Stackoverflow
Solution 4 - Ruby on-Rails	Rishav Rastogi	View Answer on Stackoverflow

undefined method `devise_for' in rails

Ruby on-Rails Problem Overview

Ruby on-Rails Solutions

Solution 1 - Ruby on-Rails

Solution 2 - Ruby on-Rails

Solution 3 - Ruby on-Rails

Solution 4 - Ruby on-Rails

Difference between Array.length = 0 and Array =[]?

Have I reached the limits of the size of objects JavaScript in my browser can handle?

Attributions