Generate Entity-Relationship diagrams from Rails ActiveModels

Hey people! Documenting your code is really crucial for projects regardless of the size of the project. There are a lot of stuff that must be documented in a project. You have various tools to generate documentation for your code. I am going to show you a tool, a gem, that allows you to document your database models. When I was doing my Pacman (github.com/steverob/student-marks) I used an online uml tool called “dbdsgnr” to document my database. But I had to make many chances to my database schema and updating the Entity Relationship diagram I had on that website was getting tedious. At one point I dropped the whole idea of maintaining that piece of documentation. When I completed my project (pending testing), I wanted to document my database and I was searching for a tool that would document my rails project by reading the ActiveRecord models that I have. That was when I found this really cool gem called ‘rails-erd’.

This gem is maintained at github/voormedia/rails-rd and the project website is rails-erd.rubyforge.org. Installation of this gem is pretty easy. It depends upon a graphics tool called Graphviz.

You can install graphviz on Ubuntu using the command,

sudo apt-get install graphviz

Now add ‘rails-erd’ to your project’s Gemfile under the development group. So it would look like,
group :development do
gem "rails-erd"
end

Now run ‘bundle install’. This will enable your project to use the rails-erd gem.

We have installed the gem and its dependency. All we have to do now is to run a simple rake task to generate the ERD. The command is,

rake erd

This will generate “ERD.pdf” file in the application root. Neat huh? The best thing about this is that you can customize the way the output is generated by passing in many options. The various customizations are clearly explained in the project’s website. But mostly you wouldn’t need much customization. And I can tell you, the output is quite awesome. The entities are spaced well and the overall alignment of the diagram is quite brilliant. It looks like as though someone had manually aligned the entire thing. Okay, you’ll know what I am saying when you see the output pdf that I got for my project. Here it is. Click the image to get a better view.

See? Its just awesome. For more information regarding the gem visit rails-erd.rubyforge.org.

Steve

Installing Ruby, Rails, MySQL and Apache on a fresh Ubuntu 12.04 installation

The first challenge I faced when I started using Ubuntu was moving my Wubi installation inside Windows to a separate partition. Thats when I understood how one should find his/her way around the problems they face using Linux. Linux has one of the biggest support base on the internet. You can find solutions to almost all problems you face in the web. The only thing you need to do is a simple and proper Google search and you’ll fix whatever problem you have in not time at all! But unfortunately many who are new to this whole idea find it really difficult using Linux. This is because they are completed immersed in and used to the way Windows works. And so whenever they face some problem in Linux, like a dependency issue, they call you or text you and ask you to fix their problems. Unlike in windows where you get generic error messages with an error code, Linux provides verbose details about the kind of error that has occurred. People must make use of this information to find solutions to their problems.

Okay enough said! When I started learning Ruby I wanted to install Ruby on my Ubuntu 11.10 installation. But I really didnt know that I already Ruby pre-installed! Not knowing this I started installing Ruby and I faced a lotta issues. I had no idea what was happening. Then I tried removing Ruby. Then after my failed attempts to remove Ruby completely I installed RVM. Then I installed a Ruby version via RVM. But then gems like rails etc just wouldn’t install. Me being a Linux beginner back then found it really irritating and annoying to the extent that I considered dumping the whole idea of learning Ruby. But the pure elegance of Ruby and the thirst to learn Rails made me keep pushing. Finally after two days I got Ruby and Rails working on my PC without re-installing Ubuntu . Since then I’ve made several Ruby and Rails installations on many computers. I faced a lotta issues, especially dependency problems when installing Ruby, Rails, MySQL etc. So I decided to write this post to tell those beginners out there, the stuff they would need to properly install Rails etc.

A handy tool for our college staff

Hello people!! Its been a really long while since I posted anything here. Its been a really good 6 or 7 months for me both academically and personally. Been through a lot of changes, learnt new stuff, decided on my main field of interest etc! Well… the main thing is, Im Back! Ive jumped over to the Ruby on Rails platform now. And I think I love this platform. Its a joy to write code in Ruby and extra joy to use the goodies provided by Rails.

I also have undertaken a project for my college to manage marks and attendance which is almost complete. I will write an exclusive post about that in coming days.

Ok. Before I begin this post I cant help mentioning how good Chelsea are performing this season! We’re on course for a Title win!

Ok okay… My college’s management is very demanding. When our university results come, the staff are required to get the results from the results websites, analyse the results and generate reports on the very same day which can be a really challenging and tiresome task given the large number of students in each batch.

I always wanted to help then out by giving them an easy way around this cumbersome job. Ive tried finding loopholes and vulnerabilities in the University Server but hit dead ends all the time. Finally I decided that the only way (atleast for me) to get the results was to parse the results from the website directly from the HTML page. I had this idea in mind but did not implement it until the results came for my 6th semester!

That night I was reading stuff when one of my friends texted me saying that the results have come. I opened the results website without any sorta excitement or expectations coz I already know that Anna University (the uni to which my college is affiliated to) is known for throwing big surprises. And they did not dissapoint! An average result once again (for me). Well I had to do something to divert my mind. So I thought of writing the app to download the results! And my word! It was a brilliant idea

Foreign Author vs Local Author

Reblogged from creativentechno:

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Why this topic Foreign Author vs Local Author ?

If you WERE , ARE or WILL take up Engineering or any Professional Course then this topic is sure to hit your mind at some point of time.

Everyone loves to be the best Engineer hoping to work on some creative stuff and do great innovations. But the point is "Does the education system of today teaches us to be creative?"

Read more… 682 more words

Java TicTacToe

Hello people! Wow its been a while since I posted something here…! I must say I really miss writing stuff and I promise I wont get into a ‘writer’s block’ again. Hopefully .. A helluva lot of things happened in the last two months and I’ve got loads to say. But in this post Im just gonna publish a small application that I wrote sometime ago. Its a TicTacToe game application. There’s not much to be learnt from this particular program but I really want to get outta this impasse and hence Im posting this today.

I actually wrote this code to show off some of the really cool features of Java to one of my friends who also wrote the same application in a “C++”-esque style. And btw that friend of mine even developed code for the computer player. But after completing his code he sadly realized the basic fact that you cannot win in TicTacToe if you play perfectly!! Hehe So I did not venture into that area. Well to be honest, Im not really interested in writing AI apps. But I thought of adding Network Multiplayer functionality to this application since I love network programming. But unfortunately I havent had the time to do so.

Anywaiz the application works like this – the game is autostarted once launched and the status bar indicates which player’s turn its now and rest is just simple tictactoe! And at the end of the game the app is automatically reset.

Onto the code..

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.util.logging.Logger;

/**
* TicTacToe Application
* @author Steve Robinson
* @version 1.0
*/

class TicTacToeFrame extends JFrame
{

	JButton [][] buttons= new JButton[3][3];
	JTextField statusBar;
	GamePanel panel;
	Integer turn;
	GameListener listener=new GameListener();
	Integer count;

	public TicTacToeFrame()
	{
		setLayout(new BorderLayout());

		panel=new GamePanel();
		add(panel,BorderLayout.CENTER);

		statusBar=new JTextField("Player1's Turn");
		statusBar.setEditable(false);
		add(statusBar,BorderLayout.SOUTH);

		setTitle("Tic Tac Toe!");
		setVisible(true);
		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		setBounds(400,400,300,300);
	}

	class GamePanel extends JPanel
	{

		public GamePanel()
		{
			setLayout(new GridLayout(3,3));
			turn =1;
			count=0;
			for(int i=0;i<3;i++)
				for(int j=0;j<3;j++)			{
					buttons[i][j]=new JButton();
					buttons[i][j].putClientProperty("INDEX", new Integer[]{i,j});
					buttons[i][j].putClientProperty("OWNER", null);
					buttons[i][j].addActionListener(listener);
					add(buttons[i][j]);
				}
		}
	}

	class GameListener implements ActionListener
	{
		public void actionPerformed(ActionEvent e)
		{
			count++;
			JButton b=(JButton)e.getSource();
			Integer[]index=(Integer[]) b.getClientProperty("INDEX");

			//System.out.println(turn);	//turn       											//			//System.out.println("["+index[0]+"]"+"["+index[1]+"]");  							//
			b.putClientProperty("OWNER", turn);
			Icon ico=new ImageIcon(turn.toString()+".gif");
			b.setIcon(ico);
			b.setEnabled(false);
			boolean result=checkVictoryCondition(index);
			if(result)
			{
				JOptionPane.showMessageDialog(null, "Player "+turn.toString()+" Wins");
				initComponents();
			}
			else
			{
				if(turn==1)
				{
					turn=2;
					statusBar.setText("Player2's Turn");
				}
				else
				{
					turn=1;
					statusBar.setText("Player1's Turn");
				}
			}
			if(count==9)
			{
				JOptionPane.showMessageDialog(null, "Match is a draw!");
				initComponents();

			}

		}

		Integer getOwner(JButton b)
		{
			return (Integer)b.getClientProperty("OWNER");
		}

		//PrintButtonMap for Diagnostics
		void printbuttonMap(Integer [][]bMap)
		{
			for(int i=0;i				for(int j=0;j					System.out.print(bMap[i][j]+" ");
				System.out.println("");
			}
		}

		boolean checkVictoryCondition(Integer [] index)
		{
			/*Integer[][]buttonMap=new Integer[][] {
					{ getOwner(buttons[0][0]),getOwner(buttons[0][1]),getOwner(buttons[0][2])},
					{ getOwner(buttons[1][0]),getOwner(buttons[1][1]),getOwner(buttons[1][2])},
					{ getOwner(buttons[2][0]),getOwner(buttons[2][1]),getOwner(buttons[2][2])}
			};

			printbuttonMap(buttonMap); */

			Integer a=index[0];
			Integer b=index[1];
			int i;

			//check row
			for(i=0;i<3;i++)		{
				if(getOwner(buttons[a][i])!=getOwner(buttons[a][b]))
					break;
			}
			if(i==3)
				return true;

			//check column
			for(i=0;i<3;i++)		{
				if(getOwner(buttons[i][b])!=getOwner(buttons[a][b]))
					break;
			}
			if(i==3)
				return true;

			//check diagonal
			if((a==2&&b==2)||(a==0&&b==0)||(a==1&&b==1)||(a==0&&b==2)||(a==2&&b==0))
			{
				//left diagonal
				for(i=0;i					if(getOwner(buttons[i][i])!=getOwner(buttons[a][b]))
						break;
				if(i==3)
					return true;

				//right diagonal
				if((getOwner(buttons[0][2])==getOwner(buttons[a][b]))&&(getOwner(buttons[1][1])==getOwner(buttons[a][b]))&&(getOwner(buttons[2][0])==getOwner(buttons[a][b])))
					return true;

				}

			return false;

		}
	}

	void initComponents()
	{
		for(int i=0;i<3;i++)			
                         for(int j=0;j<3;j++)		{
				buttons[i][j].putClientProperty("INDEX", new Integer[]{i,j});
				buttons[i][j].putClientProperty("OWNER",null);
				buttons[i][j].setIcon(null);
				buttons[i][j].setEnabled(true);
				turn=1;
				count=0;
				statusBar.setText("Player1's Turn");

			}
	}

}

class TicTacToe {

	public static void main(String[] args) {
		EventQueue.invokeLater(new Runnable(){
			public void run()
			{
				TicTacToeFrame frame=new TicTacToeFrame();
			}
		});

	}

}

The code is rather straightforward. Ive used two properties in the Buttons to store some information used for checking the winning condition. One is the “OWNER” property which indicates which user currently owns the square and the “INDEX” property which indicates the square’s index in the grid (ie [1,1], [1,2]… etc) Once any player clicks on a square, the OWNER property is updated and the victoryCondition is checked by using the OWNER properties of all the buttons. The rest of the code is self explanatory.

And adding keyboard support for the second player is a pretty easy job. As they say… “I leave that as an exercise”! Hahaha Well I really hope I get some time so that I can add network functionality to this application.
Cheers,
Steve.

—–

I forgot to attach the image icon files that will be used by the application. You can download it from here…

 http://www.mediafire.com/?d7d93v2342dxind

Just extract the contents to the folder that contains the code. Thanks to my friend “Gur Png” for telling me about this. 
-Steve