How to access asp controls in a class file

Question

I have created a panel in my page view (tour.aspx file). Now I want to access it in my class file (add_tour.cs file).

This is my panel:

<asp:Panel ID="itinerary_panel" runat="server"></asp:Panel>

This is my code behind tour.aspx file:

add_tour tour_obj = new add_tour();
int days_count = 2;
tour_obj.textbox_generator(days_count);

And this code is in add_tour.cs file:

public void textbox_generator(int days_count)
{

}

Now how to access the panel from aspx file? Please help.

Your class should not touch the controls. The code behind should handle gathering values and passing them to other classes. — mason, Feb 12 '17 at 14:35
Why do you want a class other than the code behind touching your page anyways? What do you intend to do? — mason, Feb 12 '17 at 14:49
I asked you what you want to do with it. That's important. What are you intending to do with this panel from your other class? If you don't give the full context of what you're after, it's unlikely you will receive a good answer. — mason, Feb 12 '17 at 14:52
`txt_desc = new TextBox(); txt_desc.ID = "txt_desc"; itinerary_panel.Controls.Add(txt_desc);` — Ajay Chorge, Feb 12 '17 at 14:56
but i am using it lots of time so i want to create a method in my class file so i can access it when will i need that — Ajay Chorge, Feb 12 '17 at 14:58

score 1 · Answer 1 · answered Feb 12 '17 at 15:05

There's no need to actually add the text boxes to the panel from this class.

public List<TextBox> textbox_generator(int days_count)
{
    var textBoxes = new List<TextBox>();

    for(int i = 0; i < days_count; i++)
    {
        txt_desc = new TextBox();
        txt_desc.ID = "txt_desc" + i.ToString();
        txt_desc.CssClass = "form-control";
        txt_desc.Attributes.Add("placeholder", "Enter day " + i + " description");
        txt_desc.TextMode = TextBoxMode.MultiLine;
        textBoxes.Add(txt_desc);          
    }

    return textBoxes;
}

Then change your code behind to:

add_tour tour_obj = new add_tour();
int days_count = 2;
var textBoxes = tour_obj.textbox_generator(days_count);
foreach(var textBox in textBoxes)
{
    itinerary_panel.Controls.Add(textBox);
}

Note that you need to be careful where you add these controls in the page lifecycle. See Microsoft documentation.

This keeps your textbox_generator from needing to know anything about the specific page using it.

Also, you should really align your naming conventions with C# standards. Use PascalCasing. textbox_generator should be TextBoxGenerator etc. And you can probably make textbox_generator into a static method if it doesn't need to access any fields or properties of its class.

score 1 · Answer 2 · edited May 23 '17 at 12:09

1

If you really wanted your other class to itself add the controls directly to the panel, then you would just pass a reference to the panel from the code behind to the class.

public void textbox_generator(int days_count, Panel panel)
{
    for(int i = 0; i < days_count; i++)
    {
        txt_desc = new TextBox();
        txt_desc.ID = "txt_desc" + i.ToString();
        txt_desc.CssClass = "form-control";
        txt_desc.Attributes.Add("placeholder", "Enter day " + i + " description");
        txt_desc.TextMode = TextBoxMode.MultiLine;
        panel.Controls.Add(txt_desc);          
    }
}

and call this this way from your code behind:

add_tour tour_obj = new add_tour();
int days_count = 2;
var textBoxes = tour_obj.textbox_generator(days_count, itinerary_panel);

This works because itinerary_panel actually is a reference to the panel. See Passing Objects By Reference or Value in C#. However, it's often a bad idea to have a method modify the state in that manner.

edited May 23 '17 at 12:09

Community

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answered Feb 12 '17 at 15:16

mason

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yes its working... and if i want to get the value from all those textboxs then what should i use? Ajax or Page_PreInit? – Ajay Chorge Feb 12 '17 at 15:26
Can I ask why you're using web forms and not MVC? – mason Feb 12 '17 at 15:31
because this is small scale of website application that's why i am making it with the use of web forms... there are only some dynamic pages. – Ajay Chorge Feb 12 '17 at 17:39
@AjayChorge If you're just getting started, learn ASP.NET MVC. Don't waste your time with Web Forms. Web Forms will be going away, is slow, and is a terrible framework. – mason Feb 12 '17 at 17:43
Thanks @mason can you please suggest me some material which is available online? Which will helps me learn MVC Framework. – Ajay Chorge Feb 13 '17 at 09:37
@AjayChorge I've found various videos to be helpful. See [these](https://channel9.msdn.com/Series/Introduction-to-ASP-NET-MVC) for ASP.NET MVC (watch them in order) and [this](https://channel9.msdn.com/Events/TechEd/NorthAmerica/2014/DEV-B412) for Dependency Injection. – mason Feb 13 '17 at 12:40

How to access asp controls in a class file

2 Answers2