quesions about Website Form compared with Console Project

Question

Hi

i started with WSP (website form) with Visual Studio and i have some little questions, compared with the classic Console project and OOP programming.

Thanks.

1)
public partial class MyClass_sel : System.Web.UI.Page
{
internal int tot=5;
//public int tot=5;
//protected int tot=5;
//private int tot=5;

private void Page_Load(object sender, EventArgs e)
{
Label1.Text = tot.ToString();
...

Every access modifiers works. Which one is best here?
How come that Page_Load is accessible here? It's private, so ...
-----------------------------------------
2)
public partial class MyClass_sel : System.Web.UI.Page
{
internal DropDownList dd;
internal SqlCommand comd;
internal string sql;
internal SqlDataReader dtreader;

protected void Page_Load(object sender, EventArgs e)

{
dd = DropDownList;
string m = "";
ListItem z;

using (SqlConnection mConnection = new SqlConnection(ConfigurationManager.ConnectionStrings["myconnect"].ConnectionString))
{
mConnection.Open();
sql = "select distinct gem from leden";
comd = new SqlCommand(sql, mConnection);
dtreader = comd.ExecuteReader();
if (dtreader.HasRows)
{
while (dtreader.Read())
{
m = dtreader.GetString(0);
z = new ListItem(m);
dd.Items.Add(z);
}
}
dtreader.Close();
mConnection.Close();
}
}

private void Button1_Click(object sender, EventArgs e)
{
...

Line Button1_ClickObject is inaccessible due to protection level at line with { (just after if (dtreader.HasRows)). Why is that? Both methods are in the same class, so ...
----------------------------------------------------
3)
public partial class MyClass_sel : System.Web.UI.Page
{
public int tot;

public class Test
{
Label1.Text = tot.ToString();
}
...
The name Label1 (exists in aspx file) doesn't exist in current context. How can it be reached from a class?
------------------------------------------

Sachin Singh · Answer

I said so because access modifiers are meant for accessing a class member in other classes but in the case of web forms, MyClass_Sel is not a simple class, so you can't access any of its members outside this class anyway, so there is no point of access modifiers, they are just private and are accessible within the same page only. if you really want to call the Page_Load() inside the button click event, which is 100% wrong and against the software architecture rules, you can do this as shown below this .Form1_Load(null,null); private void Button1_Click(object sender, EventArgs e) { this .Form1_Load(null,null); Label1.text= "ok" ; }

Sachin Singh · Answer

First, No oop's concept is applicable to your MyClass_Sel. In webForms every code-behind class, in your case, MyClass_Sel is inherited from System.Web.UI.Page which makes the class a special class, so you can't apply any oops concept means you can't create an object of MyClass_Sel and invoke its methods like Button1_Click() method. So, there is no reusability. Also, at one line we fetch data from the data access layer or directly using ado.net and on the next line, we set the UI element, as you are setting the Label's Text property, so we can't do unit testing as well. Now come to your questions, 1. Each access modifier has its own purpose, like private means accessible within the class only, internal means accessible within the project only, public means everywhere, etc. But these concepts are not applicable within a code-behind class because you can't access the MyClass_Sel anyway as it is not a normal class, so it doesn't matter how many members and Methods it contains, you will never be able to call them using objects. That is why we follow n-tier architecture. 2.Page_Load() is an event, apart from This event there are many events within the page life cycle, that fires on each request, doesn't matter you want them or not, they just fire, this is the biggest failure of web forms. 3. You can't class any event like Button_Click(), considering them as a method, no they are not method because MyClass_Sel is not a class, as I mentioned above, so no oops concept is applicable here. 4.You can't access an aspx element outside the class it belongs to, the aspx and the aspx.cs both are same class, one is UI and the other is Code, and they are partial, so they understand each other, this is the power of Partial class, but are tightly coupled so you can't access them in other class, means elements on a.aspx are only accessible to a.aspx.cs only. The Test class in your case is a normal class, not a special class(system.web.UI.Page), and not a part of the same page so the label is not accessible here.

Valerie Meunier · Answer

ok, thanks

Valerie Meunier · Answer

Thanks for replying. It will b my fault, but I still don't understand why Page_Load event can't reach Button_Click1 event. You said " But these (access modifier) concepts are not applicable within a code-behind class".. So why do i get the error "not accessible due to protection level"? I tried with any code e.g. like this: private void Button1_Click(object sender, EventArgs e) { Label1.text="ok"; } Thanks again.

Rajanikant Hawaldar · Answer

1)you have to choose access modifier based on requirement/need, if you want 'tot' variable to use within same class then mark it as private, if want to access 'tot' when you create object of class then mark it as public, if you want 'tot' accessibilty in derived class then mark it as internal i con't explain all modifiers here, i recommend you to read below article. https://www.c-sharpcorner.com/uploadfile/puranindia/what-are-access-modifiers-in-C-Sharp/ Page_Load event is private, you can access and call in the same class. you can also change it. 2) Question is not clear because we dont know what code is in button click and tell what your trying to do. 3) Label1 is child to MyClass_sel class and its default access modifier is not allowing to access in nested class so you have to change access modifier in order to access it.