CODEWITHSUNDEEP
c#winforms
ush
ush

Reputation: 815

How do I update a TextBox from a form other than its parent?

I would like to update a TextBox from an arbitrary form. Could you please suggest a way to do so?

Upvotes: 0

Views: 930

Answers (3)

zzandy
zzandy

Reputation: 2353

You should take Jon's advice. The other way might be something as dirty as this:

// Bad practice
foreach (var child in theOtherForm.Controls){
    if(child.Name == '_otherControlName')
    {
        (child as TextBox).Text = _thisTextBox.text;
    }
}

You may need to check some types and some panel's child controls as well.

Upvotes: 0

Jon Skeet
Jon Skeet

Reputation: 1499770

Basically the same way you'd do anything with another object. You need to have a reference to the other form, and if it's a different type it has to expose the text box you're interested in as a property, or have a method to set the text. So for example, you might have:

public class FirstForm : Form
{
    private TextBox nameInput;
    public TextBox NameInput { get { return nameInput; } }

    ...
}

public class SecondForm : Form
{
    private TextBox otherNameInput;
    private FirstForm firstForm;

    public void CopyValue()
    {
        firstForm.NameInput.Text = otherNameInput.Text;
    }
}

Or putting the textbox responsibility in the first form:

public class FirstForm : Form
{
    private TextBox nameInput;
    public string Name
    { 
        get { return nameInput.Text; } 
        set { nameInput.Text = value; }
    }

    ...
}

public class SecondForm : Form
{
    private TextBox otherNameInput;
    private FirstForm firstForm;

    public void CopyValue()
    {
        firstForm.Name = otherNameInput.Text;
    }
}

There are various other ways to skin the cat, but those are the most common. How you get the reference to the FirstForm into the SecondForm will vary - it may be passed into the constructor for SecondForm, or it could be created by SecondForm itself. That will depend on the rest of your UI.

Note that this assumes the two forms use the same UI thread. It's possible (but relatively uncommon) to have different UI threads for different windows, in which case you'd need to use Control.Invoke/BeginInvoke.

Upvotes: 3

RC1140
RC1140

Reputation: 8653

Change the class and override the constructor of the form to pass in the data that you want. In the constructor store the varialble being passed in , into a member variable

Upvotes: 0

Related Questions