How to obtain the name of the dynamically created label your clicking on

Hello

I have labels dynamically created for which i have this code to run when one is double clicked

Code:

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Private Sub label_DoubleClick(ByVal sender As System.Object, ByVal e As System.EventArgs)
       
    For Each Labelname As Label In Me.Controls.OfType(Of Label)().ToArray
            If Labelname.Name.Substring(0, 3) = ID Then
                If Labelname.BackColor = Color.Yellow Then
                    openbooking = True
                    Dim f2 As BookingForm
                    f2 = New BookingForm
                    f2.Visible = True
                    openbooking = True

                Else

                    If MessageBox.Show("Mark as collected?", " ", _
                    MessageBoxButtons.OKCancel, MessageBoxIcon.Question) Then
                        Labelname.BackColor = Color.Yellow

                    Else
                    End If
                End If

            End If
        Next


    End Sub

End Class

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I need to set the variable "ID" to the name of the dynamically created label that is clicked on so that it changes its color and the name is then passed to the next form but cant figure how i get it!

interesting thing about events... not only does it send in the event arguments... but it also sends in the control that invoked the event... so in your event handler, you know the control that is the sender of the event...

oh sure... it seems like an ordinary object... but that's because all controls inherit from object... and they can be cast to their more specific type if you know what it is...

-tg

Use DirectCast to get the sender:

Code:

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Dim myLable As Label = DirectCast(sender, Label)

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From there to access the control you'd use myLabel.<property>

That's assuming that you gave the label a name in the first place, of course. You'd be amazed how many people forget!

Quote:

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Originally Posted by dunfiddlin

That's assuming that you gave the label a name in the first place, of course. You'd be amazed how many people forget!

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That's true, I can't tell you how many times I've created a dynamic control and forgot to name them!

I'd further point out that we're talking about the .Name property control....
Dim myLabel as New Label ... that's not a name... that's just the variable...

yeah... I think we've all been caught by that before... I'll even admit to falling for it more than once...

-tg

@tg - I'm curious...

If you are going to have "centralized" events for handling lots of labels that you added to a form - what is the downfall of not naming them. You access them through the SENDER anyway - right?

Quote:

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Originally Posted by szlamany

@tg - I'm curious...

If you are going to have "centralized" events for handling lots of labels that you added to a form - what is the downfall of not naming them. You access them through the SENDER anyway - right?

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What if you're wanting the name property. In this case, the OP set the label's name as an "ID". I must admit, I'd rather store that information in the .Tag property, but in this specific case the OP needs the name property. Besides, it's just good practice to name your objects as opposed to letting VS giving them a default name.

I thought he was adding them dynamically - thus the need for a NAME at runtime is kind of useless - right? The name is for the IDE and you to get along - right?

And I agree - the TAG property is where you put [edit]additional info about the control[/edit].

When I did VB.Net coding I always named my LABELS and TEXTBOX to exactly match my FIELD names from tables, since I auto-binded these to datasource dynamically at runtime.

Personally if I'm going to add a silly label at design time for a prompt on the screen I never really cared if I left the default name of LABEL1 or LABEL123 in place.

nvm...

The Tag is type Object. If you want to use it to store the control's name, that's fine but you'll have to cast it back to string when retrieving it where as if you use the Name property, no casting is needed. Besides, it always feels better when you use the right tool for the job ;)

I certainly wasn't saying to put the NAME value in the TAG property!! I was indicating that I would use the TAG for it's purpose of storing additional info about the control.

Sorry if I was too vague.

I back out of this thread ;)

Quote:

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Originally Posted by stanav

The Tag is type Object. If you want to use it to store the control's name, that's fine but you'll have to cast it back to string when retrieving it where as if you use the Name property, no casting is needed. Besides, it always feels better when you use the right tool for the job ;)

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Yeah, I'm with szlamany. I meant that I'd store the ID value(or any other info like that) in the Tag, not the Name.

Sorry I misunderstood your idea in the last post... I'm so ashamed of myself for being such a sloppy reader. I'll try to read more carefully next time. :)

No problem! We are all talking big-stuff around a little problem of the OP not realizing SENDER is the object already available to serve the need.

Quote:

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Originally Posted by dday9

Use DirectCast to get the sender:

Code:

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Dim myLable As Label = DirectCast(sender, Label)

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From there to access the control you'd use myLabel.<property>

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Thankyou. What do i define sender as?

Quote:

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Originally Posted by Stuw

Thankyou. What do i define sender as?

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Ignore me, too early!

SENDER come in to you as the PARAMETER of the event function already

Code:

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Private Sub label_DoubleClick(ByVal sender As System.Object, ByVal e As System.EventArgs)

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You simply use the DirectCast statement to take the "generic" object of SENDER and cast it into the type of object that you are already aware that it must be

Code:

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Dim myLabel As Label = DirectCast(sender, Label)

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- notice the second parameter of DirectCast? That is the "type" to cast it into - and that would be LABEL in this case.

Now you have a new reference to the "generic" object that is no longer generic - it is now a specific object.

Use MyLabel.xxxxx to reference any of the method or properties of the LABEL that was actually clicked.

So - you never need to know the NAME of the label clicked - you already have the reference you need.

Quote:

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Originally Posted by szlamany

SENDER come in to you as the PARAMETER of the event function already

Code:

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Private Sub label_DoubleClick(ByVal sender As System.Object, ByVal e As System.EventArgs)

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You simply use the DirectCast statement to take the "generic" object of SENDER and cast it into the type of object that you are already aware that it must be

Code:

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Dim myLabel As Label = DirectCast(sender, Label)

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- notice the second parameter of DirectCast? That is the "type" to cast it into - and that would be LABEL in this case.

Now you have a new reference to the "generic" object that is no longer generic - it is now a specific object.

Use MyLabel.xxxxx to reference any of the method or properties of the LABEL that was actually clicked.

So - you never need to know the NAME of the label clicked - you already have the reference you need.

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Thanks, realised later i had paste it into the wrong bit!!

How do i now change the color of the dynamically created label from a timer? Ive tried this but it dosent accept the name of the label

Code:

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Private Sub Timer1_Tick(sender As System.Object, e As System.EventArgs) Handles Timer1.Tick

        Timer1.Enabled = False
        Timer1.Stop()

        SqlConnection1.Open()

        'Enters the sql command to run'

        SqlCommand1.CommandText = "SELECT * FROM Equiploans WHERE Equiploans.Dateout = ('" + Date.Today + "') "

        'Runs command'

        SqlCommand1.ExecuteNonQuery()

        'Dims the process that reads the database'

        Dim myreader As SqlClient.SqlDataReader

        myreader = SqlCommand1.ExecuteReader()

        Dim x As Object

        'From that row get these values'

        For Each x In myreader

            Timein = myreader.GetString(6)

            Dim ODID As String

            ODID = myreader.GetString(0)

            item1time = (dateout + " " + Timein)

            currentdatetime = Date.Now

            If currentdatetime > item1time Then

                MessageBox.Show("Overdue")

                Dim myLabelOD As Object

                myLabelOD.Name = ODID

                myLabelOD.BackColor = Color.Red


            End If

        Next

        myreader.Close()

        SqlConnection1.Close()

    End Sub

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When you are in the label click - put sender into the TIMER1.TAG

Timer1.Tag = Sender

Now when you are in the timer event - you have the SENDER from the original label click

Im going to have labels which have been created but not necessarily clicked on, is there another way?

If ODID has the name of a control then

Code:

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        Me.Controls(ODID).BackColor = Color.Red

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Quote:

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Originally Posted by dbasnett

If ODID has the name of a control then

Code:

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        Me.Controls(ODID).BackColor = Color.Red

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Thankyou!!

Sorry to be a pain but i need to access it from another form too, i thought it would just be this but alas not!

Code:

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form1.Controls(item1).BackColor = Color.Green

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Item1 being the labels name on form 1

Do you ever use the WATCH or QUICK WATCH windows?

Set a break point where you want to change the color to green and then put Form1 into the Watch window - click the plus sign to open the object - you can examine what's available.

Or put Forms1.Controls into the Watch window...

Or open the IMMEDIATE window and do line-by-line attempts.

It's a nice way for you to see what "is available" in the object you are attempting to access...

No never so that dosent help me

Why does that not help you? Have you never set a BREAK POINT and run your code and had it stop at that point to examine what is available in the objects you are working with?

If not - then you should.

Quote:

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Originally Posted by szlamany

...If not - then you should.

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Agreed. There is a link in my signature that might interest you. Actually there are a couple ;)

I find tracepoints actually very useful as well. :) That watch window is a lifesaver though too. I don't think people realize how useful it is until they actually fool around with it enough times.