Project 4. ASP.NET Forms — Sklyarenko Vlad

01 · The task

Develop an application using a Web Form

The goal of the work is to learn to write code in Web Forms. These are the steps from the lecture. Tick them off as you go.

0 of 7 done

Open the site folder in Visual Studio: File, Open, Web Site (Shift+Alt+O). In the lecture it is a copy of the site on your computer, folder Projects\6.
Add a Web Form: right-click the folder, Add, Web Form. Choose Visual C# and tick Place code in separate file.
Two files appear: Default.aspx (the markup) and Default.aspx.cs (the C# code). The page opens by default.
In Design mode drag a Button and a Label from the Toolbox onto the form.
Rename them with Hungarian notation: the button becomes cmbStart, the label lblResult. (Optional if you are short on time.)
Double-click the button. Visual Studio creates the handler cmbStart_Click() and writes OnClick="cmbStart_Click" into the .aspx.
Write the code, press Run (Google Chrome button) and test the result.

On this site the pair is named project-4-form.aspx and project-4-form.aspx.cs instead of Default.aspx, so it can sit next to the other projects.

02 · Try it

Press Start and watch the code run

This is a browser copy of the Web Form with the same logic. Pick which class goes into each seat of the family array, press Start, and follow the call from the button down to the label.

family[0] = new …

family[1] = new …

project-4-form.aspx

Project 4. ASP.NET OOP

03 · OOP

One parent, two children

APerson says a method can be changed (virtual). AMan and AWoman inherit from it (: APerson) and change it (override). The array is typed APerson[], yet each call runs the version of the real object. That is polymorphism. Change the selects above to see it.

04 · The real files

The ASP.NET page

Here is the markup and the code-behind. The label and the button are server controls (runat="server"), and OnClick connects the button to the C# method.

From a console program to a Web Form

The lecture shows the same program as a console application. Almost nothing changes, only the entry and the output.

	Console program	Web Form
Where it starts	`Main()`	`cmbStart_Click()`, after a click
Methods	`static`	`internal`, of the page class
Output	`Console.Write(result)`	`lblResult.Text = result`
New line	`"\n\r"`	`"<br>"`

Open the real page

This button opens project-4-form.aspx. It is processed by the server, so it needs both files on an ASP.NET host. On a plain file server, or when you open the files from your computer, it will not run.

Open the ASP.NET page

05 · Notes

Names and ideas

Hungarian notation

A short prefix tells you the kind of control, so cmbStart is obviously the Start button.

Prefix	Control	Example
lbl	Label	`lblResult`
cmb	Button (the name used in the lecture)	`cmbStart`
txt	TextBox	`txtName`
chk	CheckBox	`chkAgree`
ddl	DropDownList	`ddlCity`

Model, View, ViewModel
The Model builds the answer, the View shows it, and the ViewModel calls both in order.
Round trip
A click sends the page to the server. The C# code runs there, and the server sends back a new page.
Partial class
The page class is split in two files: the markup (.aspx) and your code (.aspx.cs).