Check if any textbox is empty and fill it with a value

Question

private void btnSaveInformation_Click(object sender, EventArgs e)
    {
        foreach (Control child in Controls)
        {
            if (child is TextBox)
            {
                TextBox tb = child as TextBox;
                if (string.IsNullOrEmpty(tb.Text))
                {
                    tb.Text = @"N/A";
                }
            }
        }
        //var bal = new StudentBal
        //{
        //    FirstName = txtFirstName.Text
        //};
        //bal.InsertStudent(bal);
    }

What I want to achieve is for the system to check if there is any blank checkbox, and I have numerous in the form, and if it is blank, then assign a value of "N/A". What am I doing wrong with the codeI have? Thank you.

Nothing wrong. Are your text boxes inside other controls like group boxes or panels? — Tommy, Jun 28 '16 at 02:56
Possible duplicate of [Set multiple TextBoxes editable after button click on WinForm](http://stackoverflow.com/questions/34743783/set-multiple-textboxes-editable-after-button-click-on-winform) — Salah Akbari, Jun 28 '16 at 04:46

score 2 · Accepted Answer · edited May 23 '17 at 12:24

2

Are the textboxes placed in panels or other grouping controls? If so, the form's Controls collection would not contain references to them; they would only contain the immediate children (which would be the panels, etc.)

If they are contained within a group control or panel, you would want to do something like this instead:

foreach (Control child in myGroupPanel.Controls)
{
    if (child is TextBox) { // your additional code here }
}

If you want a more robust method, the following show different ways of getting a list of all controls:

How to get all children of a parent control?

How to get ALL child controls of a Windows Forms form of a specific type (Button/Textbox)?

edited May 23 '17 at 12:24

Community

1
1

answered Jun 28 '16 at 03:07

Nailbite

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The textboxes are in one group box but in different panels. I tried your suggestion but still no ace. – Ibanez1408 Jun 28 '16 at 03:22
The quick and dirty solution is to identify the immediate parents of the textboxes and create a concatenated list you can loop through. You can use LINQ's Concat for this: var controls = panel1.Controls.Concat(panel2.Controls).Concat(panel3.Controls).Concat(...); foreach(Control child in controls) { ... }. This is quick and dirty though and isn't scalable once you start adding more text boxes. In that scenario, you would want something like those in the links I added. – Nailbite Jun 28 '16 at 03:28
Okay Nailbite. Thanks! I'll study the links you provided. It's gonna be abit hard since I don't know LINQ yet – Ibanez1408 Jun 28 '16 at 03:45

sujith karivelil · Answer 2 · 2016-06-28T03:02:36.257

You could use child.GetType() to get the type of the control while iterating the group of controls, then compare the same with the typeof(TextBox) with will help you to filter textBoxes from the control collection. try this:

foreach (Control child in Controls)
{
    if (child.GetType() == typeof(TextBox))
    {
        TextBox tb = (TextBox)child;
        if (string.IsNullOrEmpty(tb.Text))
        {
            tb.Text = @"N/A";
        }
    }
}

Or else you can use iterate through filtered collection like the following(assuming that Controls is a collection of controls):

foreach (Control child in Controls.OfType<TextBox>().ToList())
{
     TextBox tb = (TextBox)child;
     if (string.IsNullOrEmpty(tb.Text))
     {
         tb.Text = @"N/A";
     }
}

score 0 · Answer 3 · answered Jun 28 '16 at 03:14

I see nothing wrong in your code. I suspect controls that you are looking are nested controls.

I would suggest flatten the hierarchy and get all the (nested)controls and then look for specific type.

static Func<Control, IEnumerable<Control>> GetControls =
        (control) => control
            .Controls
            .Cast<Control>().SelectMany(x => GetControls(x))
            .Concat(control.Controls.Cast<Control>());

Now you could use the above delegate in your code like shown below.

foreach (TextBox tb in  GetControls(this).OfType<TextBox>())
{
    if (string.IsNullOrEmpty(tb.Text))
    {
        tb.Text = @"N/A";
    }
}

Check if any textbox is empty and fill it with a value

3 Answers3