mammals blog

“Dynamic finders with hash attributes for creation”

Jon(CJ) — Thu, 19 Feb 2009 11:14:47 +0000

Here’s a typical situation:

tag = Tag.find_by_name(name)
if tag.nil?
tag = Tag.create(:name => name, :creator => current_user)
end

You’d think the way to do that would be with the find_or_create_by_name dynamic finder, but that doesn’t work since there’s no way to search by name only, but create by name and creator. Well, that’s just not right. So here’s what we’ll do:

Tag.find_or_create_by_name(:name => name, :creator => current_user)

It’s not a big deal or something I use every day, but I like it anyway.

Source : google .

Difference between http://sitename.com and http://www.sitename.com

sachinchoudhary — Thu, 08 Jan 2009 14:29:07 +0000

Most of the time when your domain is example after you commit your application you can access your site by typing http://example.com or by http://www.example.com.

suppose if login on http://example.com and after you login if you add www in the address bar then your cookies and session are all lost. to avoid this you have to write a redirect rule in the apache.

In the rewriting rule you just have to choose only one format of the url

RewriteCond %{HTTP_HOST} ^yoursite\.com [NC]
RewriteRule (.*) http://www.yoursite.com/$1 [R=301,L]

Mammals In Black

Jon(CJ) — Sat, 13 Dec 2008 15:01:27 +0000

Even we promote people to wear blue clothings, jeans, shirts , notice the CAP even its blue .

Don't forget to notice the Black T-shirt and the Blue whale logo .

“Sum/Avg method in Rails , save a query”

Jon(CJ) — Tue, 09 Dec 2008 10:41:51 +0000

Ever wondered about the Calculations in Rails, I used to use the group_by in SQL or select to do many calculations while fetching the results , but sometimes Rails doesnt allow to use group etc , like when we are doing AJAX calls in v2.1.0 of rails .

Then Joejeet helped me to get the following calculations methods , it was so beautiful that my 3 line of code was convered to 1 single line.

Code
@rating_sum = Rating.sum(‘rating’, :conditions =>["rateable_id = ? and rateable_type = ?", @rating.rateable_id, @rating.rateable_type])

There are other methods like Avg,minimum, max,count etc available under
Module: ActiveRecord::Calculations::ClassMethods

calculations, calculations in rails, sum, avg, minimum, rails

“Changing the class of a div using rails NOT JS”

Jon(CJ) — Tue, 09 Dec 2008 10:33:20 +0000

Consider we need to change the class of a particular DIV/SPAN , I was wondering how we could have done using some default rails method and NOT Javascript as what we can do in Javascript the same we can do using Rails but in lesser time and number of lines of code.
Using google with the correct key words resulted in the following

Javascript

function change(id, newclass)
{
identity=document.getElementById(id);
identity.className=newclass;
}

Rails

page["task_#{params[:id]}”].toggle_class_name “completed”

rails, javascript, page.toggle_class_name, change class name of div in rails

“SQL inner joins the right way “

Jon(CJ) — Wed, 26 Nov 2008 15:05:16 +0000

The right way
————————————-
select s.CompanyName
from Suppliers as s
where exists
(
select * from products p
inner join categories c on p.CategoryID = c.CategoryID
where c.CategoryName = “Seafood”
and p.SupplierID=s.SupplierID
)
—————————————-

The wrong way
————————————————
SELECT DISTINCT Suppliers.CompanyName
FROM Suppliers INNER JOIN (Categories INNER JOIN Products ON
Categories.CategoryID = Products.CategoryID) ON Suppliers.SupplierID =
Products.SupplierID
WHERE (((Categories.CategoryName)=”Seafood”))
————————————————

sql

Javascript function to set a web page as home page for IE and Firefox Compatible

sachinchoudhary — Fri, 21 Nov 2008 04:24:21 +0000

To make a page as home page by clicking a link you just have to right this javascript function in you .js file

function setHome()
  {
   if (document.all)
   {
   document.body.style.behavior=’url(#default#homepage)’;
   document.body.setHomePage(’http://url_of_page.com’);

   }
   else if (window.sidebar)
   {
   if(window.netscape)
   {
   try
   {
   netscape.security.PrivilegeManager.enablePrivilege(”UniversalXPConnect”);
   }
   catch(e)
   {
   alert(”this action was aviod by your browser，if you want to enable，please enter about:config in your address line,and change the value of signed.applets.codebase_principal_support to true”);
}
}
var prefs = Components.classes['@mozilla.org/preferences-service;1'].getService(Components. interfaces.nsIPrefBranch);
prefs.setCharPref(’browser.startup.homepage’,’http://url_of_page.com’);
}
}

After adding this you only have to call this javascript method.

make your home page

and that’s all

This is compatible for IE and firefox

rails helper method to redirect to back page visited

sachinchoudhary — Fri, 21 Nov 2008 04:22:46 +0000

Sometime we get stuckin a problem when we have go back last page which user visited but rails doesn’t comes with a helper method which gets beck to the last page visitted, But everytime a request goeas to the server a request object is created by the rails which contains the url of the page from which user comes to current page so we can use that as follows :-

helper method which you have to put in your application controller

class ApplicationController < ActionController::Base

:helper_method :redirect_back

def redirect_back(redirect_opts = nil)
redirect_opts ||= home_url
request.env["HTTP_REFERER"] ? (request.env["HTTP_REFERER"]) : (redirect_opts)
end

end

sometimes if the firewall is actvated on the client side then this request.env["HTTP_REFERER"]doesn’t gets set, so we have to check this condition also. if the request.env["HTTP_REFERER"] is not created then we have to redirect it to different url in my case i use the home_url but you can change as per your requirement.

you can use this method from your views.

If you want to call this as method from controller you have 2 options

either use this method as bellow

def redirect_back(redirect_opts = nil)
redirect_opts ||= home_url
redirect_to request.env["HTTP_REFERER"] ? (request.env["HTTP_REFERER"]) : (redirect_opts)
end

2. write redirect_to and call this method from controller as bellow

def create

—— some codes ——-

redirect_to redirect_back(clubs_path)

end

if request.env["HTTP_REFERER"] not get set then the transfer goes to clubs and if you don’t pass any parameter then by default it will get you to the home page

Blue Whale Labs Developer Blog

adarshpandit — Fri, 21 Nov 2008 04:21:06 +0000

This blog is intended to be used for code sharing, tips, tricks, and coding challenges. Also use this for asking for help from others.

Please set this as your homepage and use tags liberally. This is what you make of it – there are no ground rules so have fun!

“Debugging in rails”

Jon(CJ) — Thu, 20 Nov 2008 13:15:11 +0000

Well ever thought of debugging the rails application , there are many ways , one way which I liked of lately was the debugger in action directly.
Step 1 : Install ruby-debugger gem “sudo gem install ruby-debugger –include_dependencies”
Step 2 : Dont forget to start debugging server by saying
ruby script/server –debugger
Step 3 : Say debuggger in the action, the console will open in the command line for the code written below to debugger

eg:
def foo
debugger
@object = Active.find(:all)
end
When in that case in the command line we will get a rbd : opened , where you can debug the object like @object.size etc
Thats it enjoy , there are some other methods like , , puts etc which I guess all of us already know abt.