[.net] C#: Set text box from a static method
Author
Hi, I have a method such as this:
private static void foo() {...}
Now I would like to set the text in a text box on my form to some value from within this function, how can I achieve this?
Hmmm in ASP.Net you could do something like:
If you are not talking about ASP.Net I still reckon you would be able to search for the control from a root element somehow.
public static void SetTextBoxValue(System.Web.UI.Page FormPage, String ControlName, String Value){ object FormControl = FormPage.FindControl(ControlName); if (FormControl == null) return; ((System.Web.UI.WebControls.TextBox)FormControl).Text = Value;}If you are not talking about ASP.Net I still reckon you would be able to search for the control from a root element somehow.
Author
Thank you for the response but I'm looking for a solution for a desktop application.
OK then if I were to adapt the code for a Windows Forms application it would look like:
As an example, I would call it from in the application like:
ChangeText(this, "TextBox1", "New textbox text");
(assume the textbox control you want to change has the name "TextBox1").
private static void ChangeText(System.Windows.Forms.Form CurrentForm, String ControlName, String Value){ Control TempControl = CurrentForm.Controls[ControlName]; if (TempControl != null) { ((TextBox)TempControl).Text = Value; }}As an example, I would call it from in the application like:
ChangeText(this, "TextBox1", "New textbox text");
(assume the textbox control you want to change has the name "TextBox1").
To make that work, you need to pass the form as an argument to the method ("..." representing other arguments):
If you need to access controls on the Form from within a static method, then you should ask yourself why you really want that method to be static. A non-static method would be called like:
which (usually) makes more sense.
class MyForm { public static void DoSomething(MyForm frm, ...) { frm.textBox1.Text = "Something"; }}// elsewhere:MyForm.DoSomething(theForm, ...)If you need to access controls on the Form from within a static method, then you should ask yourself why you really want that method to be static. A non-static method would be called like:
theForm.DoSomething(...)which (usually) makes more sense.
Author
Thank you all for your response, unfortunately I still haven’t been able to solve my problem and I think it is partly my fault for not specifically stating my problem. My code is as follows:
What I want to do is capture that the error in ValidationCallBack and dump it in a text box, my problem is I can't do this because ValidationCallBack is a static function and I can’t pass any parameters to it. If someone could suggest a solution it would be greatly appreciated.
public void ValidXmlDoc(){ // some code before this settings.ValidationEventHandler += new ValidationEventHandler (ValidationCallBack); // some code after this}private static void ValidationCallBack(object sender, ValidationEventArgs e){ MessageBox.Show(e.Message, "Error");}What I want to do is capture that the error in ValidationCallBack and dump it in a text box, my problem is I can't do this because ValidationCallBack is a static function and I can’t pass any parameters to it. If someone could suggest a solution it would be greatly appreciated.
Author
WOW! Such a simple solution! Thank you! But just for sake of knowing, how would you solve this problem if it had to be static?
You'd have to make either the textbox, the form, or something in-between static. Usually you want to avoid static as much as possible though (I only really use 'static' on functions that don't really need an instance of a class. But in your case you need an instance in order to get at the text box member (well, I assume your validation functions are inside your Form or one of your UserControl classes).
static TextBox tbErrorMessage; // to serve as a reference to the main instance of the text box. You wouldn't actually want to "new TextBox" and assign to this.public void ValidXmlDoc(){ // some code before this tbErrorMessage = blah; //(however you would access your text box using a non-static function) settings.ValidationEventHandler += new ValidationEventHandler(ValidationCallBack);// some code after this}private static void ValidationCallBack(object sender, ValidationEventArgs e){ tbErrorMessage.Text = "VALIDATION FAILED! D:";}This topic is closed to new replies.
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