Visual Basic cannot using form when coding - vb.net

I have a form called "cancel reservation", so when i try to calling this form in my coding , it cannot be call.
Please check my attachment here
I can using call for all other form but not this one, can anyone please give some advise?
Thank you

Your form's name is most likely just Cancel_Reservation instead of formCancel_Reservation (that is, if you've not renamed it of course).
For example:
Cancel_Reservation.Close()
should do the trick.

Use show() function to call forms.If your form name is Cancel_reservartion then call like this,
Cancel_reservartion .show()
Just try it.

Related

How to use Form Controls in Modules

In my modules, I want to use my controls from my form. For example: I want to set focus on a textbox after a certain Sub.
My current solution is to make a subroutine to set all controls in a public variable (see below).
My questions:
What is the best practice? How do people usually do this?
When should I call my subroutine? (is it the first call in the FORM_LOAD sub?)
Public TBnr As TextBox
Public Sub controlsInitieren()
Set TBnr = Forms("frm_TreeView_Example").pstNr
End Sub
Well, as a general rule, while many platforms seperate out the UI part and the code part? Well, Access is quite much a different approach - it is standard fair to place the required code inside of the form "class" (all forms in Access are a "class", and you can even have muliple instances of the SAME form open more then one time).
So, in general, your code should be in the forms code (class) module.
However, you could and call a external routine.
So in the form, you could call your above routine like this:
Call MySetFocus(me, "NameOfControlToSetFocusTo")
And your sub would look like this:
Sub MySetFocus(f as form, sCtrl as string)
f(sCtrl).SetFocus
End Sub
However, as noted, the amount of code above is more code then simply in the forms code module going:
me.ControlName.SetFocus
However, while the above is a less then ideal example, passing the form "instance" (me) to a external sub or function allows you to referance any property or method or feature that exists in the form in an external routine.
So in place of say
me("LastName") = "Zoo"
In the above sample routine, you would and could go;
f("LastName") = "Zoo"
So any place you would and could use "me" in the form, you can use the form instance you passed from the form. As noted, it is a good idea to use "me", since as I noted, Access does allow multiple copies of the form to be opened at the same time - and thus your code can't distinguish between what form instance you are using unless you pass the current "in context" form. So like in JavaScript, using "this" ?
In access that current instance of the class object is "me", and you are free to pass that instance to any sub or function you want as per above.
The best practice is to use only procedures inside the form code. In such a case you refer to a text box control in this way: Me.Textbox1.SetFocus. If you want to set some controls properties during the form loading, you can do that in the frm_TreeView_Example_Initialize event;
They usually do it in the way I described at item 1;
If you want to use such a strange/unusual way you can do it calling the subroutine whenever you want. But, in order to set a specific property value of the form frm_TreeView_Example controls you can simply use frm_TreeView_Example.TextBox1.SetFocus. You can use this way of setting in a module procedure, even before the form has been shown. You can simply show it in that procedure code using at the end: frm_TreeView_Example.Show;

Refreshing form from timer in another form

I have a problem with the snippet of the code I have got to extend and improve. It is not my original code and I cannot change the logic that much of it, just to be clear.
I have one main form called MDIServer, which has a timer set for every second. In Timer.Tick I have some other code which works fine (timer is running okay). Newly, I had to check there, if one form is Active and if so, change some stuff (labels text and tags) in that form and refresh it.
I add there this code:
If IsActiveForm("frmName") Then
frmName.ChangeSomething()
End If
The Sub ChangeSomething is, how you can see, located in the form I want to refresh and do the changes. In that function I simply change the label text and tags of few controls.
My question is: Form is not refreshing => labels are not visible changed, why?
I think I tried already almost anything with Refresh() function in the ChangeSomething() function or in the timer after I called this function. Also I tried to add there new timer (in frmName) and do the changes there, which works perfectly with
Label.Text = "something new"
Label.Refresh()
So I guess problem is somewhere with the refreshing form from Timer in different form. I also tried to do it with my own InvokeReguired() function etc...
P.S. When I am debugging the code, labels and tags are changing and every single function which has to be called, is called, but it is just not visible on the form itself.
EDIT Info
formName is not declared in MDIServer explicitely and in this case and many other cases, forms are used as default instances. Timer is from System.Windows.Forms.Timer. Also MDIServer is not a MDIParent of the formName and I cannot use Me.ActiveMdiChild Is. Lets just say, these two forms are not dependent on each other in any way.. and everything is done through name of the form (default instance, so nothing like Dim frm As Form and frm = frmName).
I would be really glad for any tip or anything :D
Thanks guys,
Vojta
So, I fixed my problem after some research and the problem was (expected) that I am not calling the subroutine ChangeSOmething() for one specific instance of the form frmName. So I had to change my code, that I will call it exactly for the instance which is active and visible.
New code looks like this:
Dim frmCollection = Windows.Forms.Application.OpenForms
Dim listfrmname = frmCollection.OfType(Of frmName).ToList()
If listfrmName.Count > 0 Then
Dim tmpFrm As frmName = listVZT15.Last()
tmpFrm.ChangeSomething()
End If
I also could not use combination of frmCollection.OfType(Of frmName).Any and frmCollection.Item("frmName"), because when I was closing the form and opening again, it created new and new instances (I dont know, why it is not closing the old one, but like I said, it is not my code). So the logic is, to list all open forms of the needed type, and then take the last instance from that list and for that instance call the subroutine. Also Me.Refresh() is placed in the subroutine ChangeSomething() itself.
Thanks everyone for help, it surely helped me to understand, how the instances works here.

Send Parameter via new() or pre-set properties before calling the new form?

I would really appreciate your advice on the following:
I'm working on Windows forms using VB.NET (even though the language is irrelevant to the question at hand).
I've got a main form and wish to call out another one, however depending on a given variable I need the text on some of the new form's elements to change as well as disable some of its controls.
There are two ways I see of doing it:
Send a parameter from the main form and have some logic on the second form to deal with everything on load.
Main Form:
dim newform as new frmcalculate(byval type as string)
New Form:
public sub getexplanation(byval type as string)
select type
case "Sum"
lblexplanation.text = "this is a sum"
case "Subtraction"
lblexplanation.text = "this is a subtraction"
End sub
Set exactly what I want on the main form before calling the new form.
i.e:
dim newform as new frmcalculate()
newform.lblexplanation.text = "This is a sum"
I hope I've managed to explain it correctly.
I'm still new at this especially getting the formats right on Stackoverflow.
In the first approach the code is best managed and organized for further editing. So each form has it own code.
It is not best practice to use second approach. (Editing a form designer from another one)

How to assign an output to a label in a second form through the first form?

I wanna show the output of the calculations in a second form but I am writing the code in the first form. How can I do it?
Use the parent form name in front of the control that you are trying to work with. You may need to set the modifier to Friend.
Say that the label exists in form2 and you have code in form1 that is needing to change it. So you would do it like this: form2.label.text = "the string value here"
However, keep in mind that if the control was created or is owned by a different thread then the one that is trying to edit the control, you will receive a runtime exception.
To resolve that you will need to create a delegate for the calling sub or function.

How to load code before on form load

I have some code I need to load in before I want the code to run (I want to create a table), I tried 'Onload' but this is not soon enough, basically I'm looking for something just like OnInit() where I can load all I need before anything actually occurs. My problem is that it's checking for the table way to early (Because it hasn't been created yet)
http://gyazo.com/c731783b9b2a01dcaf93f92a170f61ba
So really I just need some help with calling code before the actual onLoad event is called.
THanks
Is OnOpen event suitable?
And you can have empty RecordSource in form and set it after you have created table.
1. open form in design view
2. copy RecordSource
3. in you event(onOped or onLoad) put after table creation code
Me.RecordSource = "COPY'ed recordsource"