Develop Reference

Can I use Tag property to store it is name?

I am using below method to validate data within textbox in groupbox
so for improvement of user Feedback for example
message text Please enter First Name
where First Name is the label for textbox, so I used Textbox.Tag to store the name of textbox to achieve it since there is no link between the Textbox and it is Label
I search and found that I can use the Tag property to store anything but I wan to be sure of using it by the I told you about
Is there any problem with that ?
public int ValidateData()
{
foreach (Control cont in GB_PatientInfo.Controls)
{
if (cont is TextBox)
{
if (string.IsNullOrWhiteSpace(cont.Text.Trim()))
{
MessageBox.Show("enter data " + cont.Tag, "Message", MessageBoxButtons.OK, MessageBoxIcon.Information, MessageBoxDefaultButton.Button1, MessageBoxOptions.RtlReading);
cont.BackColor = Color.Red;
cont.Focus();
return -1;
}
}
}
return 1;
}
Thanks

As you have read, you can store any type that derives from object (i.e. everything) in the Control.Tag property so storing the name of a label is fine.

The use of the Tag property does not influence your application. You can store whatever you want in there with no problem.

As it's already mentioned in other answers, it's OK to use Tag property to store any kind of additional information about the control, including a display name.
But have you ever noticed how ToolTip lets you to set ToolTip for your control at design-time?
A ToolTip, ErrorProvider or HelpProvider are examples of extender provider components. They add some properties to the controls at design-time. You also can create such component for DisplayName by implementing IExtenderProvider.
Example
The following code shows you how easily you can create a component called DisplayNameExtender. When you drop an instance of this component on the form, then a new property will be added to design-time of controls, you can set the value to the property
at design-time: DisplayName on diaplayNameExtender1.
Then at run-time, whenever you want to get the value of DisplayName for a control, it's enough to find it this way:
var displayName = displayNameExtender1.GetDisplayName(control);
Here is the code for DisplayNameExtender component:
using System.Collections;
using System.ComponentModel;
using System.Windows.Forms;
[ProvideProperty("DisplayName", typeof(Control))]
public class DisplayNameExtender : Component, IExtenderProvider
{
private Hashtable displayNameValues = new Hashtable();
public bool CanExtend(object extendee)
{
return (extendee is Control && !(extendee is Form));
}
public string GetDisplayName(Control control)
{
if (displayNameValues.ContainsKey(control))
return (string)displayNameValues[control];
return null;
}
public void SetDisplayName(Control control, string value)
{
if (string.IsNullOrEmpty(value))
displayNameValues.Remove(control);
else
displayNameValues[control] = value;
}
}

Accessing components of another form

I have two Forms in my application. A Form has the following fields: txtPower, txtTension and txtCurrent. I would like to access the values ​​filled in these TextBox through another Form. In the second Form I instantiated an object of the first Form (MotorForm), however I do not have access to the TextBox.
public MacroForm()
{
InitializeComponent();
MotorForm motorForm = new MotorForm();
motorForm.Show();
}
Is there any way?

Please do not expose the controls in your form. Never. (Unless you have a really good reason.)
If the problem is simple enough not to use MVVM (or the like) in your program (which you should consider for every program that's but trivial), you should expose the values of the instantiated form via properties. Think
public string Power
{
get { return txtPower.Text; }
set
{
if(ValidatePower(value))
{
txtPower.Text = value;
}
else
{
// throw ??
}
}
}
If we can make a sensible assumption about the type of the value we could extend this to
public double Power
{
get
{
// parse the value
// validate the value
// throw if not valid ??
// return the value
}
set
{
// validate the value
// set the value in the text box
}
}
If you exposed the txtPower object, you'd make the instantiating class depend on implementation details of the instantiated class, which is virtually never a good thing.

It seems that your problem is a perfect situation for using ShowDialog for opening your form.
To accomplish this, you need to change the Modifiers property of the controls you want to access on MotorForm and set them to Public. And also set the DialogResult property of your form somewhere to a desired value i.e OK. Anyway the easier way to do this is to set it on the button that is supposed to close the form. Suppose OK or CANCEL buttons.
Then you can create your form this way:
MotorForm motorForm = new MotorForm();
if(motorForm.ShowDialog() == DialogResult.OK)
{
string myValue = motorForm.txtPower.Text; //you can access your values this way
}

How to expose a label in a user control with c#

I have made a user control with a pic box and a blank label. How do I expose the label so I can update the text value from my main .net application. I have not written any c# code in about 10 years, and was just thrown a project. All I have for code is:
namespace RHeader1
{
public partial class RHeader : UserControl
{
public RHeader()
{
InitializeComponent();
}
}
}
Please for give my stupidity. I know I need to do a get/set but?????

I presume you mean because controls are not public, the proper way to access them are via a property (which I agree with) - so you can just expose a property which updates the label directly - I'm presuming this is winforms
public string Label
{
get { return label1.Text; }
set { label1.Text = value; }
}

Use this:
Label lbl= (Label)myUserControl.FindName("yourlabelname");
This way you can find and update your label control settled in the UserControl.

You could change the Label's modifier property to public, this will result in the labels properties been visible from the UC's property window and also allow you to do something like
uc.label.Text = "foo";

if you haven't delclared the label:
label1 = new label();
then
label1.text = "some text";
where you can replace "Some text" with any string value.

C# custom control property: unable to set DefaultValue field

I am trying to set a custom C# control property.
Here's my code:
/* Cancel's button text */
[Category("ComboTouch"),
Description("Text to display in cancel button"),
DefaultValue("Cancel")]
public String ct_cancelButtonText { get; set; }
I can get the property when I use the customized control in other projects (as you can see in the image); but configuration parameter DefaultValue seems not to work.
Could anybody help me? Thank you very much.
01/10/13 Update. Thank you very much for your answers, you solved my problem.
I would like to share how I finally could set the default value automatically:
private String m_cancelButtonText="Cancel";
/* Cancel's button text */
[Category("ComboTouch"),
Description("Text to display in cancel button"),
DefaultValue("Cancel")]
public String ct_cancelButtonText
{
get
{
return m_cancelButtonText;
}
set
{
m_cancelButtonText = value;
}
}
One curiosity: please check the format of 'Cancel' text. If I set DefaultValue type; it looks like normal text. But if I don't, it looks like bold text. I know it's silly; but I would like to know why it is that way. Thank you.

As noted in documentation:
A DefaultValueAttribute will not cause a member to be automatically initialized with the attribute's value. You must set the initial value in your code.

Why my control's properties won't change outside its class?

I'm new in C# but not new to coding --being doing it for almost two decades--, and have a problem with properties in a custom control I'm building, which inherits from a Panel. When I put my properties, I can see them in the Designer properties list and can even set them, but when running my little application, it seems these properties values are not used. The same if I change a property programatically: no error but my control does nothing, it is like they are not properly set. However, if I do it programatically whithin the class, they do work. My guess is that something in my properties set/get stuff is not right. Please see the following code chunk of how I'm doing it:
public class ColorStrip : Panel
{
// properties
// ------------------------------------------
// size of color clusters (boxes)
private int _clusterSize = 20;
// controls if show the buttons panel
private Boolean _showButtons;
// property setters/getters
// ------------------------------------------
// clusterSize...
public int clusterSize
{
get { return _clusterSize; }
set { _clusterSize = value; }
}
// showButtons...
public Boolean showButtons
{
get { return _showButtons; }
set { Console.Write(_showButtons); _showButtons = value; }
}
....
So in my form, for instance in the load or even in a click event somewhere, if I put colorStrip1.showButtons = false; or colorStrip1.showButtons = true; whatever (colorStrip1 would be the instance name after placing the control in the form in design mode)... console.write says always 'false'; Even if I set it in the design properties list as 'true' it will not reflect the settled value, even if I default it to true, it will never change externally. Any ideas? Non of the methods get the new and externally settled property value neither, obviously the getter/setter thing is not working. Seems to me I'm not doing right the way I set or get my properties outside the class. It works only inside it, as a charm...Any help...very appreciate!
Cheers
lithium
p.s. TO CLARIFY SOLUTION:
Setting the property in this case didn't work because I was trying to use a new set value within the constructor, which seems can't get the new values since it is, well, building the thing. If I change the property value in Design mode > Property editor or in code externally to the object, say in it's parent form's load event, it will change it but readable for all methods except the constructor, of course :)

It's likely an issue of the order of execution. Your property setter just sets a variable, but doesn't actually trigger anything on the control to update the state related to this variable (e.g. adding or showing the buttons I assume).
When you set the property befre the rest of the initialization is done, the value is being used, otherwise it isn't because during the initial go the default value is still the property value.
You need to act on the setter, here's some pseudocode to illustrate:
set {
_showButtons = value;
if (alreadyInitialized) {
UpdateButtons();
}
}
Note: make sure to first set the value, then act - otherwise you end up using the old value (just like your Console.Write() is doing).

The quoted code doesn't look problematic. Are you sure you're referencing the same instance of ColorStrip? Also, check your .Designer.cs file to ensure that the code setting the property is there.
In fact, try simplifying your code by using auto-implementing properties:
public int clusterSize { get;set;}
public Boolean showButtons {get;set;}
public ColorStrip() { ... clusterSize = 20; ... }