How to get contents of textboxes created dinamically?

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Hello.
I'm using C# in Visual Studio and created an application in Windows forms. There's a routine that deals with balance in banks and creates text boxes for the amount in a groupbox. The number of text boxes depends on the number of bank accounts, retrieved from a database.
Another routine uses the data in the textboxes. My problem is that I don't know how to get the data in the dinamically created textboxes. My first routine is:

        <pre>private void Frm_Saldo_Load(object sender, EventArgs e)
        {
            int i;
            int Nbancos = 0;
            Dtp_DataSaldo.Text = DateTime.Now.ToShortDateString();
            DataTable Tab1 = Banco.LeBancos();
            DataRow[] Linha = Tab1.Select(null, null, DataViewRowState.CurrentRows);
            int Nitem = Tab1.Rows.Count;

// Caso haja mais que 3 bancos, deve-se ajustar o tamanho do formulário e do groupbox
            if (Nitem > 3)
            {
                Height = 375 + (Nitem - 3) * 5;
                Gb_Bancos.Height = 180 + (Nitem - 3) * 5;
            }
            Gb_Bancos.Tag = 0;
            for (i = 0; i < Nitem; i++)
            {
                var Rotulo = new Label();
                Rotulo.Name = "Lb_Banco" + i.ToString();
                Rotulo.Text = Linha[i].ItemArray[2].ToString();
                Rotulo.Location = new System.Drawing.Point(10, 40 + 30 * i);
                Rotulo.Size = new Size(150, 26);
                Gb_Bancos.Controls.Add(Rotulo);

                var CampoSaldo = new TextBox();
                CampoSaldo.Name = "Tb_Saldo" + i.ToString();
                CampoSaldo.Font = FonteNormal;
                CampoSaldo.Location = new System.Drawing.Point(160, 40 + 30 * i);
                Gb_Bancos.Controls.Add(CampoSaldo);

                var CampoCod = new TextBox();
                CampoCod.Name = "Tb_Cod" + i.ToString();
                CampoCod.Font = FonteNormal;
                CampoCod.Location = new System.Drawing.Point(180, 40 + 30 * i);
                CampoCod.Text = Linha[i].ItemArray[0].ToString();
                CampoCod.Visible = false;
                Gb_Bancos.Controls.Add(CampoCod);
                Nbancos += 1;
                Gb_Bancos.Tag = Nbancos;
            }
            MostraSaldo();
        }

The routine MostraSaldo() is where I have the problem. Does anyone have a suggestion? Thank you.

What I have tried:

I tried the following routine:

private void MostraSaldo()
{
    int Nbancos = Convert.ToInt32(Gb_Bancos.Tag);
    int i, j;
    var CampoSaldo = new TextBox();
    var CampoCod = new TextBox();
    DataTable Tab1 = SaldoBanco.LeSaldo(Dtp_DataSaldo.Text);
    DataRow[] Linha = Tab1.Select(null, null, DataViewRowState.CurrentRows);
    int Nitem = Tab1.Rows.Count;
    if (Nitem > 0)
    {
        for (i = 0; i < Nbancos; i++)
        {
            CampoSaldo.Name = "Tb_Saldo" + i.ToString();
            CampoCod.Name = "Tb_Cod" + i.ToString();
            MessageBox.Show(CampoCod.Name + " = " + CampoCod.Text);
            for (j = 0; j < Nitem; j++)
                if (CampoCod.Text == Linha[j].ItemArray[0].ToString())
                    CampoSaldo.Text = Linha[j].ItemArray[1].ToString();
        }
    }
}

but it didn't work.

Posted 18-Jun-21 11:49am

Ismael Oliveira 2021

Updated 18-Jun-21 20:02pm

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OriginalGriff · Answer 1 · 2021-06-18T19:56:00

Solution 1

The first thing I'd do is change the way you do that: instead of creating a label and two textboxes each time, move them into a UserControl and crate one instance of that in your loop instead. It them becomes responsible for it's content, which keeps them together and makes them easier to find. Add Saldo, Cod, and AccName properties to the new control for access and you're good to go.

Then when you want to find them, just loop through Gb_Bancos.Controls and look for the AccountControl instances:

C#

foreach (Control c in Gb_Bancos.Controls)
   {
   if (c is AccountControl ac)
      {
      var saldo = ac.Saldo;
      var cod = ac.Cod;
      }
   }

Give it a go - it sounds complicated, but it isn't really - and it makes the rest of your code much, much cleaner!

Posted 18-Jun-21 19:56pm

OriginalGriff

Comments

[no name] 19-Jun-21 2:08am

8 hours later and we both think about the same question at the same time ...

Ismael Oliveira 2021 19-Jun-21 11:02am

Hi, OriginalGriff. I think your idea is good, but I'm starting in creating User controls. If you could give me a hint, I would appreciate it. Or if you have other way of doing what I need with my code, it also would be great. Thanks.

OriginalGriff 19-Jun-21 11:39am

Add a UserControl to your Project - Right click the project in eth solution explorer and select "Add Item", just as you do for a form. Give it a sensible name!
Drop a label and two textboxes onto it - give them appropriate names.
Add three properties - one for the label, and one each for the textboxes:

public string Data
    {
    get { return tbData.Text; }
    set { tbData.Text = value; }
    }

Compile.
You can now treat it just like any other control: drag it from the toolbox, or create it dynamically just as you do your label and text boxes.

Ismael Oliveira 2021 20-Jun-21 20:53pm

Hi, OriginalGriff.
I tried your suggestion, and I had another problem: when I insert the user control via programming, its name is always the name of the control: camposBancos1. So I don't know how to differenciate each instance. How is it possible to have different names for these instances?
Thanks.

OriginalGriff 21-Jun-21 1:08am

Um ... yes. Just change the Name property of the instance ... but what use is that to you, since you can't access the name from code:

MyControl mc = new MyControl();
mc.Name = $"MyName{index++}";

Works fine, but you can't later say

MyName1.Text = "Hello world";

Why do you need to name them?

Ismael Oliveira 2021 21-Jun-21 10:38am

I have a form where the client sees his bank accounts and his dayly balance. The label receives the bank name. One of the textboxes receives the balance and the second textbox receives tre bank code. The client can update the values. As I don't know in how many banks he has accounts, in the form, programatically, I insert a number of textboxes and labels equal to his bank accounts. When he clicks OK I must save the values in the DB. That's why I need the nams of the textboxes. Can you help me? Thanks.

OriginalGriff 21-Jun-21 10:48am

You don't need the names of the textboxes, just their content. The bank infor becomes part of each User Control (which keeps all related data together) and your form access it via properties you create.
At a guess, the Label is the bank name, the textboxes hold the balance and account number perhaps?

Because you don't know how many accounts there will be, you look through the Controls of the form and process each User Control instance in there as a separate account.
They don't need names!

Make sense?

Ismael Oliveira 2021 21-Jun-21 12:51pm

There are, in fact, 2 problems. First, when I create the form, and insert the user control n times, it's ok to insert the correct data, but even changing the location of each user control at the end only the last one appears. To use this user control (which I called camposBanco) I insert it once and it receives a name (camposBanco1). Then, during programming, I insert the component inserted into the project (camposBanco1). So when I change the location, the original object changes. See my code.
The second problem: when user clicks OK, I must look all Code fields (textboxes), and update the DB with the contents of the balance field. As you suggested, I must use a foreach, right? But it's complicated, because inside this foreach I must make a loop. If you were develloping this, how would you do?
What am I doing wrong? If you can, please hep me. If you think it's annoyng for you, let it go. Thanks again.

OriginalGriff 21-Jun-21 14:02pm

I think the problem is that you don't understand instances properly.
Last's ignore computers, and talk about cars. You drive your car to the shops, and put your mobile in the glove box. When you get back home, you open the glove box and there is your phone, yes?
But ... if your shopping trip was to buy a new car, would you expect to find your mobile in the new car when you got home?

Of course not - you know that your first car and your second car are different instances of the same class: Car.

"Your car" is a name you use to refer to the car you drive - when you buy a new car you replace the value in "Your car" with the new one.

"Your car" is a variable, which can contain a single instance of a Car.
If you want to simulate a carpark, you have spaces which each hold a single car and you can fill the park with new cars:

spaces.Add(new Car(Manufacturer.Mercedes, Color.Black));
spaces.Add(new Car(Manufacturer.Ford, Color.Green));
spaces.Add(new Car(Manufacturer.Citroen, Color.Red));

You don't need to name each car you create, because you just remember the number of the space you stored it in:

foreach (Car c in spaces)
   {
   Console.WriteLine($"{c.Manufacturer}, {c.Color}");
   }

Similarly, when you want to add multiple UserControls to the Controls collection, you don't need separate names for them - just the ID that links the bank to your DB. Just the same as if you stored balances separately in an array - you don't expect each double value in the array to have a separate name because you can use the index to get at specific values.

So when you read a row from your DB, create a new UserControl with the bank and balance data, and also give it the DB Row ID - the user doesn't get to see that, but it's a property in the control anyway. Then add that to your Controls collection.
When you write new values to the DB, you use the ID property to tell it which row to UPDATE.

This isn't complicated, not really - it's the way pretty much everything works!

Ismael Oliveira 2021 21-Jun-21 18:21pm

Ok, OriginalGriff. I understood. Now, if my control has two textBoxes and one label (eg. Tb1, Tb2 and Lb1) how can I extract the contents of Tb2? Thanks again.

OriginalGriff 22-Jun-21 1:55am

You do know what Properties are, right? You have been using them pretty much all the Time!

The idea is that controls (including forms) don't expose their internals - they expose properties which access those textboxes and so on instead, and present a "simple string" or similar to the outside world. Just as a TextBox control does: it has a Text property which you can get or set, but how it handles that inside the control is irrelevant to you!

So when I said:
"Drop a label and two textboxes onto it - give them appropriate names.
Add three properties - one for the label, and one each for the textboxes" did you just go "bleep" over that?

Ismael Oliveira 2021 22-Jun-21 17:54pm

Ok, OriginalGriff.
Thank you for your help!

OriginalGriff 23-Jun-21 1:10am

You're welcome!

Gerry Schmitz · Answer 2 · 2021-06-18T20:02:00

Solution 2

Add a List<textbox> xxx = new List<textbox>() to your form / class.

When you create a new textbox and add it to your groupbox, also add it to the new list.

When you need "only" the textboxes, they're right there; you don't have to iterate the groupbox control collection.

You can even pass the list of textboxes to another routine for processing.

Posted 18-Jun-21 20:02pm

Gerry Schmitz

Comments

Ismael Oliveira 2021 19-Jun-21 11:03am

Gerry. When I retrieve from DB the account balance, I must put this value into the appropriate field (textBox). I think a list would not help me do this. Od did I misunderstand what you said?