The code i am trying to run is a simple one. get text from a Textbox and display that via MsgBox. now i probably have done this a million times but i get a strange error. The Code is :
Dim s As String = FromDateTEX.Text.ToString
MsgBox(s)
I get this error from second line :
System.InvalidCastException: 'Specified cast is not valid.'
Here is the strange part : Debugger shows value for s which is correct. here is the screenshot :
What am i doing wrong here ?
Edit :
Even this code gets the same error :
MsgBox(“hello”)
One line above, you access the property EditValue of control DomainLUE. If LUE stands for LookUpEdit, do you happen to be using a 3rd party component library from a company like DevExpress?
If that is the case, is FromDateTEX a textbox (TextEdit) control from this library too? In that case, FromDateTEX might also expose an EditValue property. Then you might try to convert that value to a string:
Dim s As String = FromDateTEX.EditValue?.ToString()
I am not sure why the Text property is problematic here. I would expect it to work just fine. Very strange.
Oh, by the way, sometimes Visual Studio goes a little bit berserk. Closing Visual Studio, optionally deleting the .suo file, restarting Visual Studio and reopening the solution might help too...
Turns out the error was from the above line. LookupEdit 's EditValue was in fact a Short and it needed a Convert to Integer.
Related
This seemed to be working but just stopped and I'm not sure what I changed to cause this.
I have a listbox on a form. (a single select listbox).
To extract the value, I can do me.listboxName.Column(0) and that works perfectly.
However, that's not the code I want to use. (as I will reference it from another form )
Form_myformName.listboxName.Column(0)
is what I had, and it worked and now it's stopped. It still works for similar code on other forms, so I'm not sure what's happened.
If I type in me.name, it tells me correctly that my form name is "myFormName".
If I type in Form_myFormName., it prompts me with the name of my list box so I know I have the names correct. However, if I try to extract the value using:
Form_myformName.listboxName.Column(0)
it gives me a value of Null, despite the listbox having a selected value. (which I can sucessfully extract by using me.listboxname etc)
hopefully that makes sense. anyone know what I'm doing wrong?
Try it this way:
Forms("myformname").listboxName.Column(0)
I hope that helps.
Im working on this VB project on visual studio 2013, and when i make changes to a form and try to save it, keep giving me bellow error doesnt even compile or save.
Code generation for property 'DisplayType' failed. Error was: 'The value '0' is not valid value for the enum 'EnumDisplayType'.'
Cant figure out the reason for this.
Fixed the issue.
The problem was with enum as its expecting 0 index.
I experienced this issue while simply trying to rename a button in a MS VS 2017 Windows Forms Application. The error I received was:
Code generation for property 'Protocol' failed. Error was: 'The value '0' is not a valid value for the enum 'ProtocolTypes'.'
As you know, System.Windows.Forms.Button control does not contain a Protocol property. You will need to guess which other object within the application holds that property, and then assign the appropriate value to it.
I created a new project with default form in it. I named the form as mdiparentform, set its isMdiContainer property to true. inserted another form. I called it on Mdi Form load as follows -
Dim Home As New Home()
Home.MdiParent = Me
Home.Show()
So far, everything is working correctly.
Then, I inserted a button in this form Home and tried to show another form as a child form, from this.
Dim settings As New settings()
settings.MdiParent = mdiparentform
settings.Show()
But this code is not even compiling. It shows a red line below mdiparentform and throw this error
'mdiparentform' is a type and cannot be used as an expression.
I am confused why is this error occurring and how to rectify it?
well i just found the blunder. There was a Form Name (the one which is shown in Property window, when we select the form) and Form File Name (the one with .VB extension) mismatch.
p.s. - Although it's newbie's (like me) mistake. But posting answer to my own question, because I thought it might be helpful for future searches to this error.
Consider the following vb.net code for an office add-in (for access):
td = db.TableDefs(objectName)
For Each fld In td.Fields
For Each fldprp In fld.Properties
Debug.Print(fldprp.Value.ToString())
Next
Next
the variable "db" is a .net representation of the access vba return result from "Application.CurrentDB()". "td" is of type "DAO.TableDefClass".
This code throws an exception of type "InvalidOperationException" when the value of the fldprp.value property cannot be determined (in Visual Studio, it shows the value as {"Invalid Operation."} in the watch window). fldprp.name, however, is available.
There are only a few properties which this occurs on. I'd like to be able to loop through all the fld.properties and output the values, but ONLY if it is not an exception.
I am pretty sure why it is happening (certain properties are not available in this context). What I need to know is how to detect this at run-time so i can skip the property.
I can't seem to find a solution that will work. Help would be greatly appreciated.
Inside the body of the inner loop, put this at the top:
If TypeOf fldprp Is InvalidOperationException Then Continue
http://msdn.microsoft.com/en-us/library/0ec5kw18%28VS.80%29.aspx
I don't know your specific situation, but what I would suggest is using an explicit filter for the object types you want to include instead of filtering out the ones you don't want to include.
I'm using VB.NET 2008.
I have an Bound DataGridView with a numeric column that can be edited. However when one selects the number and backspaces there is an error.
If I trap it in DataError Event the error message is "Input String was not in a correct format".
How can I prevent this error?
If you could provide a small sample of your code it might be more helpful, but not having that i'd guess the application is trying to convert the empty string to a number, and it is failing. I'd say your best bet is to put a try/catch in the event that occurs when the data is being updated, and mark it as "handled" (check the EventArgs for a Handled property) to keep the error from being thrown. You'll then need to do your own error checking on the actual save code once the user is done editing the column.
Turns out the problem was that I had changed the DefaultCellStyle.NullValue. I changed it back to the default (Blank) and now everything is fine.