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.
Related
I'm trying to optimize the performance of my access frontend. One of the problems I'm stumbling on is how to set a multi-window form to open immediately to a specific record, because at the moment it queries everything twice.
Essentially, I allow my users to open multiple instances of a form. That way, a user can compare multiple records by placing the windows of those forms side by side.
At the moment, my code looks like this:
Set frm = New Form_Name
frm.RecordSource = "select * from Table where id = " & ID 'ID is a variable passed to the method
I'm pretty sure back then this question was one of the building blocks I relied on.
The problem is that on the first line, access already entirely opens the form and does everything the form does when opening, such as Form_Open, Form_Current, and loading subforms. Then, when I set the recordsource, it does all (or most) of that again, which significantly slows down the process of opening the form.
Here are some of the things I've tried:
Changing the Form_Current to recognize that it's being "used" twice and only actually run the code once. The problem is that the code is already very optimized and doesn't seem to be the bottleneck, so this doesn't seem to do much. Actually opening the form seems to be the bottleneck.
Trying to change the properties of the original form so that it opens the specific record I need, but I can't seem to change the properties without it opening the form.
Looking for a way to supply arguments to the form. That doesn't seem to be supported in VBA.
One other idea that popped into my mind was creating a variable in vba with the ID of the record, setting recordsource in the form properties to fetch that variable, but then, when I would open another form and change that ID, the form
I realize that I can do this with DoCmd.OpenForm, but that doesn't give me the option to open multiple instances of the same form.
How can I achieve this? This would mean a significant performance improvement.
OK, so I actually wanted to ask this question. But just before I hit the submit button, I had an idea...
Here's the idea: you set a global variable in VBA, which you then access in the form filter command. In my case I just added Public OpeningID As Long at the top of my VBA module. Then I create a function to get that value:
Public Function getFormID() As Long
getFormID = OpeningID
End Function
Then, in the form, you can set the filter criteria as ID = getFormID(). And then when you open the form instance, you do it like this:
OpeningID = ID
Set frm = New Form_Name
OpenindID = 0 'reset this to make sure that if it's being accessed when it shouldn't, it generates a clear error
The only problem is what happens when you refresh the form, as that will call the method again. When you refresh the form via VBA, you can set the OpeningID beforehand, and to avoid users refreshing the form, you can add this to your form (don't forget to turn on Key Previews in the form settings):
Private Sub Form_KeyDown(KeyCode As Integer, Shift As Integer)
If KeyCode = vbKeyF5 Then KeyCode = 0
End Sub
Bang. Forms open almost twice as fast. Awesome.
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;
I'm trying to move the OnClick code from one of the buttons on a form to a function, but I'm having some issues. The button in question, called "Reset", changes the properties of most of the objects on the form. Stuff like:
Me.btnName.Caption = "Caption"
Me.btnName.Visible = True
Me.btnName.Top = 123
Me.btnName.Height = 456
'Etc
When moving this over to a function I can't seem to get this to work. I've tried a few different ways of writing it that I found while searching around, but none of them seem to work. I'm messing with some objects in the main form and some in the subform, so I'll show a few examples of both. Edited to include error messages
Forms("FormName").btnName.Caption = "Caption"
'Application-defined or Object-defined error
Forms("FormName").Controls("btnName").Caption = "Caption"
'Ms Access cannot find the referanced form (I've double and triple checked that it is correct)
Forms("FormName").SubFormName.Form.btnName.Caption = "Caption"
'Application-defined or Object-defined error
Forms!FormName!btnName.Caption = "Caption"
'Cannot find the referenced form
Forms!FormName!SubFormName!btnName.Caption = "Caption"
'Cannot find the field reffered to in your expression
Forms!FormName.Controls!btnName.Caption = "Caption"
'Cannot find the referanced form
Forms!FormName!SubFormName!Form.btnName.Caption = "Caption"
'MS Access can't find the field 'SubFormName'
No matter what I try of these I can't seem to get it to work. Maybe I'm just doing something simple wrong, or maybe you can't change properties like this from a function. Regardless, if anyone knows, I would appreciate the help.
Note that the function I'm trying to use is in a separate module, not in the code behind the form.
So you have a OnClick handler on some form's code-behind, responsible for assigning a bunch of properties for objects that live on that form.
What you have done is called encapsulation: outside code doesn't need to care about the Top and Height properties (and others) of the form's btnName button - truth is, outside code shouldn't even need to care that there's a button on the form.
So you're taking this nicely encapsulated object, and moving code around for no apparent reason.
If you need that functionality to be invoked from the outside, then yes, move it out of the OnClick handler.. but not outside the form's code-behind.
Move it to some Public Sub OnReset() procedure, and if outside code needs to invoke that logic, then have it call theForm.OnReset.
Private Sub ResetButton_Click()
OnReset
End Sub
Public Sub OnReset()
Me.btnName.Caption = "Caption"
Me.btnName.Visible = True
Me.btnName.Top = 123
Me.btnName.Height = 456
'Etc
End sub
That way you leave the implementation details of the form within the form itself, while giving outside code an abstraction to say "I don't care what your buttons are named; I don't care what size they are or what their captions are - but when I say 'Reset', you shall re-initialize whatever values you've got for them" - outside code doesn't need to know what Reset does specifically.
Put it this way: the day you rename that btnName button, would you rather need to simply adjust the form's code-behind, or hunt down every possible place in the entire project that could possibly be changing that button's Caption or whatever other property value?
FYI Foo!Bar.Something is late-bound code, shorthand for Foo.Item("Bar").Something: neither Bar nor Something are validated at compile-time. Contrast with Me.btnName.Whatever, where a typo is immediately picked up by the compiler: early-bound code that the compiler is able to validate should always be preferred.
You need to set the property to something:
Forms!FormName!btnName.Caption = "New Caption"
or, if on a subform:
Forms!FormName!<NameOfSubformCONTROL>.Form!btnName.Caption = "New Caption"
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)
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.