useful online tools for web programming

• Regex for ruby: http://www.rubular.com/
  
• strftime: http://strfti.me/
  
• css gradient generator: http://www.colorzilla.com/gradient-editor/
  
• css validator: http://jigsaw.w3.org/css-validator/
  
• css rounder corner generator: http://a.deveria.com/roundgen/
  
• 7 great js resources (not really a tool but useful): http://mashable.com/2011/07/03/7-great-javascript-resources
  

will be updated as i found another tools

Rails general coding style

Code:

# somethings_controller.rb
def create
  @something = Something.new params[:something]
  @something.save!
  if @something.some_state?
    @something.initialize_for_some_state
  end
  redirect_to success_url
rescue
  render :action => "failed"
end

Hint:

1. should avoid rescue without specifying the exception, in above code, use
   rescue ActiveRecord::RecordInvalid
   
2. better yet, don't use any rescue at all, use save instead of save! with some if
   
3. post processing should be done in callback.
   after_create {|something| something.initialize_for_some_state if something.some_state}
   

Better Code:

# somethings_controller.rb
def create
  @something = Something.new params[:something]
  if @something.save
    redirect_to success_url
  else
    render :action => "failed"
  end
end

---

Code:

# somethings_controller.rb
def show
  @something = Something.find(:first, :conditions => "user_id = #{current_user.id} AND id = #{params[:id]} AND name = #{params[:name]}")
  respond_to do |format|
    format.html
    format.js do
      render :js => "$('#container').html('#{escape_javascript(render :partial => "something", :object => @something)}');"
    end
    format.json do
      render :json => @something.to_json
    end
  end
end

Hint:

1. SQL injection warning! never use data from params or from user input directly in sql code. use something like this instead:
   :conditions => ["user_id = #{current_user.id} AND id = ? AND name = ?", params[:id], params[:name]]
   
2. using model relation and dynamic finder you can avoid the conditions entirely
   @something = current_user.somethings.find_by_id_and_name params[:id], params[:name]
   
3. you should check if nothing found (@something is nil)
   
4. this is just my opinion, but in most case i'll avoid using respond_to, instead i'll use 3 different view files: show.html.erb, show.js.erb, show.json.erb. rails will automatically use the correct view.
   

Better Code:

# somethings_controller.rb
def show
  @something = current_user.somethings.find_by_id_and_name params[:id], params[:name]
  render_invalid "not found" if @something.nil? # read about render_invalid in http://tech.maysora.com/2010/12/rails-renderinvalid-method.html
end

---

to be continued about model

Counting sub-string occurrence in a string

Once upon a time.. I need a way to count number of occurrence of certain sub-string (not exclusively words) inside a string.

For example, string "Aya Hirano is the best seiyuu in the world! She was mostly known as her role as Haruhi." I wanted to know how many times string "he" occurred in there.
The result should be 4, 2 in the, 1 in She and 1 in her.

By using scan method we can do that easily:

class String
  def substr_count(pattern)
    self.scan(pattern).length
  end
end

"Aya Hirano is the best seiyuu in the world! She was mostly known as her role as Haruhi.".substr_count("he") # -> 4
"Aya Hirano is the best seiyuu in the world! She was mostly known as her role as Haruhi.".substr_count(/(!|\.|\?)/) # -> 2 -> counting sentences? :D

Too simple to become share-worthy article I guess.. :P

Aborting AJAX Request

For some functions like autocomplete, usually we send ajax request whenever user stop typing (by using timeout), but if the request takes a long time to finish, user might sending another request while the previous one isn't done yet, in worst case scenario this might cause the requests complete order messed up therefore the result will be invalid.

We can prevent this by aborting previous ajax request before sending a new one.
XMLHttpRequest object have abort() function we can use for that purpose, documented here:
https://developer.mozilla.org/en/XMLHttpRequest#abort

in the following jquery script, i have a 2 text fields sending ajax request onkeyup that always completed in 2 seconds and adding the inputted text in the result div, the first one will have stackable ajax request, and the other one will prevent ajax request stacking by using abort

cookie operation functions

function setCookie(c_name,value,exdays){
  var exdate=new Date();
  exdate.setDate(exdate.getDate() + exdays);
  var c_value=escape(value) + ((exdays==null) ? "" : "; expires="+exdate.toUTCString());
  document.cookie=c_name + "=" + c_value;
}

function getCookie(c_name){
  var i,x,y,ARRcookies=document.cookie.split(";");

  for (i=0;i<ARRcookies.length;i++){
    x=ARRcookies[i].substr(0,ARRcookies[i].indexOf("="));
    y=ARRcookies[i].substr(ARRcookies[i].indexOf("=")+1);
    x=x.replace(/^\s+|\s+$/g,"");
    if (x==c_name){
      return unescape(y);
    }
  }
}

function removeCookie(c_name){
  setCookie(c_name, '', -1);
}