Scrabble Records Application v 2.0
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Introduction
The purpose of this article is to re-visit some of the issues which were experienced when implementing a simple C# application – Scrabble Records. The Scrabble Records application is a C# application which keeps a running record of scrabble game scores (and ranks players accordingly -still to be implemented!). I hope to cover some of the areas in C# which developers, new and experienced alike, will come across. Seeing as C# is relatively new, I was tired reading about it and going through the sample walkthroughs in Visual Studio.NET 2002. Walk with me through the full process of developing the Scrabble Records Application.
Implementation Tools
The development platform used will be Microsoft.NET Framework v1.0.3705, the IDE is Visual Studio.NET 2002 (a must I think for working with .NET) and of course the language of choice is C#…Visual Basic dot who?
Designing the Application
Before jumping in to write the code, we have to first of all decide what on earth the application is supposed to do. Doesn't matter if the language has 1million great new features and will make us more efficient programmers, we still have to plan. So as an overview, big picture if you will, the application will be a single user Microsoft Windows application which will allow the user to enter scores for one or more scrabble games. The information entered will be stored in a database (Microsoft Access…don't you just love MS!). The user will then be able to view the scrabble records entered. Now that we have a clear mental picture of what we want to create, we can start coding. Oh, to make it a bit more exciting so you don't fall asleep, the code name for the application is TongBei. TongBei is a martial arts fighting style (used by Frost for MK5 fans).
Enter Visual Studio.NET 2002
For developing Windows based applications using C# and the .NET framework, Visual Studio.NET will be your best friend for sure. We will first develop our main application window. In the project it is the file MainWindow.cs, this is windows form will contain the application menu which handles the main events of the application. The menu will allow the user to enter player names, then scrabble game records. The menu structure is shown in the figure below:
Figure 1 : Menu Structure
The MainWindow.cs has some interesting things that we should note. First of all, this Windows Form is special because it serves as a container for all other Windows Forms in the application. We must therefore set the IsMdiContainer property to True. This lets the compiler know that this form is a Multiple Document Interface Application (MDI Application) which will contain the child-windows with which the user will interact with in the application. Also since MainWindow.cs is the parent-window for the application, it is useful to set it's WindowState property to Maximized. This property determines the initial visual state of the form. It will be easier to manipulate child-windows having maximized the parent window, so this is the reason we set WindowState to Maximized.
The menu was created using the MainMenu control from the Windows Forms toolbox in Visual Studio.NET. Simply drag this control onto the form you wish to have the menu presented to the user and type in the menu options which will be available in the application. The figure below illustrates creating the Scrabble Records menu:
Figure 2: Creating Menu Structure
Handling Child-Windows
Ok so how do we handle the child-windows in the application? How do we 'call' the child-windows into action when they are requested by the user? Each option on the menu in the application is associated with a click event-handler. When the user selects Enter Player Record from the menu, the event-handler for that child window is invoked. It is within this event-handler that we code what events we want to occur when a particular menu item is clicked. For example the Enter Player Record menu option has the following even-handler:
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Figure 3: Enter Player Record menu item event-handler
The code is pretty much self-documenting and explains each line of the event-handler. This is also a must, commenting your code is a must. It reminds you what the heck you were trying to do when you come back later on in the application life-cycle. It's also handy for other people to learn from when they are reading your code. So when we select Enter Player Records from the menu the event handler in Figure 3 (above) is called and we create a new instance of EnterPlayerRecords.cs which is a child-form in our application, we then set MainWindow.cs to be the parent of EnterPlayerRecords.cs and once that is set up, we display the child-form to the user and that ends the event-handler.
Each menu-item is associated with a click event-handler, which calls the related child-form. Looking back to Figure 3 the child-window EnterPlayerRecords.cs was invoked once the user selected Enter Player Records from the menu in the parent window MainWindow.cs. In Scrabble Records, each menu option is associated with a task the user needs to perform, in this case it is Entering Player Records (names).
First Look Data Storage Strategy: Entering Player Records
The application essentially will have to store information which will be retrieved (it's only reason we store information anyways!) later. When using the .NET framework we have several options to store, retrieve and manipulate data. For Scrabble Records, I chose to use OleDb.NET as the data provider. The driver used to accomplish this is Microsoft.Jet.OleDb 4.0.
When the user selects Enter Player Record from the main menu, they will be presented with the following Windows Form, which is EnterPlayerRecords.cs in our application:
Figure 4: Enter Player Record(s)
The user would then Enter the Full Player Name and click OK, this information would then be written to the database. We'll examine how that is accomplished.
Visual Studio.NET provides some wizards which make connecting to data-sources and retrieving information a cinch. However the code generated by these Wizards can lead to trouble down the line and you can waste precious time trying to get drag-and-drop connections to work. The first time I wrote this application I used the Connection Wizards in Visual Studio.NET and if you needed to change something later on, it can be a hassle, so in this version, I coded the connections and retrieval from scratch and it wasn't as bad as I thought it would be. So as a general rule for C# and .NET development I'd say forget the wizards in Visual Studio.NET and code from scratch, when dealing with connecting to data-sources and retrieving data.
Connection Strings, Connection and Command Objects…
The figure below shows what we need to set up the connection to our database and insert the player names once entered:
Figure 5: Database connection and query information
We need to declare a variable to store our connection string, an OleDbConnection object as well as an OleDbCommand and a string to hold the query to insert player names. We then attempt to establish a connection to our database and catch any errors that might occur. This code is placed in the form's load method. When the form is loaded into memory, the code establishing the connection is executed. This is in the figure below:
Figure 6: Connecting to Database
We create a new OleDbConnection based on the connection string we defined in Figure 6 then open the connection by calling the Open() method on the connection object – simple. This is of course placed in a try/catch/finally control structure so as to handle any errors that might occur from attempting to connect to the datasource. And as usual comments are placed before the method to let us know what the method is supposed to do and it's good programming practice – whether coding for home or Fortune 500 enterprise – and especially if coding from home FOR a Fortune 500 enterprise.
Once we've set up the connection to the database and the user has entered a player name, we need to insert that data into the database. For the names, this is simple again. We have a table in our database called tblPlayer into which we will insert the name entered once the user clicks OK on the Enter Player Record(s) form.
To insert data into the table, this is one of several ways that can be used. Let's examine the following code:
Figure 7: Inserting user data to database
The code-snippet in Figure 7is the beginning of the event-handler for when the user clicks the OK button to enter a player name. First we check that the textBox is not blank so we know that we are dealing with actual data. Next we set the queryString to an SQL statement which inserts the player name in the textBox into the database field [Name] in the table [tblPlayer]. To perform the actual insert we create a new OleDbCommand object based on the query and connection – then we call the ExecuteNonQuery() method which executes a SQL statement against a connection.
Now we can look at the rest of the method in the figure below:
Figure 8: Remainder of event-handler for Button OK click event
The remainder of the method pretty much catches and deals with any exceptions that may occur during input by displaying the appropriate message to the user via the MessageBox.Show() method. In the finally block we clear the textbox control so that the user can enter as much names as they wish.
One note before we move on about closing connections. We need to explicitly close the connection to the datasource once we are finished with it. This is done so that we release any resources which we do not need. This is placed in the form's Dispose() method, see the figure below:
Figure 9: Cleaning up resources
Moving on…Entering Game Scores: OleDbDataAdapters, DataSets…
When the user selects Enter Game Scores from the main menu, they are presented with the following form:
Figure 10: Enter Game Scores
We will examine some of the more important features of this windows form. From Figure 10we can see that the Player 1 Name Combo Box is populated with names from the database. The code to accomplish this is shown below:
Figure 11: Binding player names from database table to Combo Box
First we do the usual connecting to the database and opening the connection and storing the SQL statement as a string. Next we create DataSet and OleDbDataAdapter objects. The DataSet is an in-memory representation of DataTable objects, and allows us to manage these tables and relationships between these tables. The DataAdapter serves as the link between the datasource and the Connection object with the DataSet object through the use of its SELECT and action query Commands.
We create an OleDbDataAdapter based on our namesQueryString and our connection object (to the database). We then call the fill method of the DataAdapter ob
ject using the DataSet object created and the DataTable name of "PlayerOneNames". Next we set the DataSource property of the PlayerOneName combo box to the DataTable – PlayerOneNames, then we set the DisplayMember property of the PlayerOneName comb box to show the name field from the database, which stores the player names – now the player names from the table in the database are displayed in the combo box on the Windows form.
The input of game data, player 1 and 2 name along with their respective scores and the date the game was played is handled in the following code-snippet:
Figure 12: Entering Game Data
The same technique used in entering the player name to the database is used here. The concept is the same, the SELECT statement is just longer that's all because we are dealing with five fields instead of one. The other thing to note is that we have to provide some sort of feedback to let the user know that the record was input successfully to the database, that is done via the MessageBox.Show() method, which includes the string feedback, which is just stores the text equivalents of what was input onto the form. There is nothing else really to this form…time to move on.
Displaying our Data
When the user selects View Player Records from the menu they are presented with a Windows form, which holds a DataGrid that displays the results of the games to date. Here is what it looks like:
Figure 13: Viewing Game Records
We will now look at the main part of the method that handles displaying the Game Records data on the Windows form:
Figure 14: Displaying Data via DataGrid
Once we have connected to the database and called the Fill() method of our OleDbDataAdapter, we simply set the DataSourceproperty of the DataGrid to the DataTable named "Results". Note that here we use ordinal dsResults.Tables[0]as opposed to string-referenced binding. Either works, as we could have also said dsResults.Tables["Results"], however in applications where performance is of great concern go with the ordinal method since using the string-referenced collection method comes with a performance and maintenance price tag.
The formatting of the DataGrid is pretty straightforward and is accomplished by setting the relevant properties of your DataGrid to suit the look-and-feel of your application. Some of the more relevant properties for formatting include: CaptionBackColor,BackColor, BackgroundColor,CaptionFont and CaptionText.
In The End…
That is pretty much the main points about the application. The Visual Studio.NET solution file with all files used in project is available for you do download. I need to implement a ranking feature for this application, so that based on game records, the user can also view Player Rankings based on how much games won and lost. I haven't found a way to do this yet, and I would welcome any suggestions or solutions to get this done. I tried to create a player class but that idea did not work out too well. Any more suggestions? I hope you enjoyed the article and that you learnt something from it.
Adrian Sobers
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