VS 2008 Passing EventHandler Delegate As Parameter
Jan 13, 2010
I have a Dialog Box that creates a Link Label for each item in a list.When one of those LinkLabels is clicked the DialogBox raises a LinkClicked event.Before, I was using code like this in the Form that was instantiating the Dialog:[code]But I don't like that for several reasons.What I want to do, and what I thought would be straight forward, was to pass the AddressOf the UserClicked PoLink Method into the ShowClickableLinksDialog Constructor and do an AddHandler within the constructor and also assign the Delegate to a Property on the Dialog so as to RemoveHandler when the Dialog is Disposed.[code]But I get a squiggly on the tempLinkClickedEventHandler after the AddressOf Operator saying: "AddressOf operand must be the name of a method (without parenthesis)"I don't get it.I've played around with a number of permutations and can't get what I feel ought to work, to work.
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Nov 6, 2010
I'd like to create a function myFunc with one parameter, which is a delegate. I should be able to call it with a delegate as parameter.E.g.[code]But how do I code myFunc, in other words, how do I enable myFunc to have it passed a delegate so that it can be called using myFunc(addressof test Func)?
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Nov 5, 2010
In C#, I could do something like this:
EventHandler handler = this.SomeEvent;
...which would allow me to, for example, do:
Delegate[] attachedHandlers = handler.GetInvocationList();
In VB.NET, I can't seem to figure out how to do a similar thing.
This doesn't work:
Dim handler As EventHandler = Me.SomeEvent
...due to the following error:
Public Event SomeEvent(sender As
Object, e As EventArgs)' is an event,
and cannot be called directly. Use a
'RaiseEvent' statement to raise an
event.
But this doesn't work either: [Code] So how can I actually get an EventHandler from an event in VB.NET? The only idea that's immediately coming to mind is to use reflection, but that seems pretty ridiculous.
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Aug 29, 2011
In my VB.NET project I wanted to run a JAR file in a separate thread. Now the question : Is it possible to pass parameters to a JAR file during run time from VB.NET??
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Jun 13, 2011
I am having trouble with a mySQL query with the .NET connector. When I create the query, it automatically creates my parameters as objects. I usually change the type to the correct type, which in this case is Date, but I get different results passing in the parameter as a date.When I do "Preview Query" as an object, I get the correct results, but bad results as a Date. I would just leave them as objects, but it errors out when I try to pass a date in.Here's the part of my query that I'm having trouble with:
(Tickets.Resolved >= str_to_date(@startDate, '%m/%d/%Y')) AND (Tickets.Resolved <= str_to_date(@endDate, '%m/%d/%Y')) AND
(Tickets.Status = 'resolved' OR
Tickets.Status = 'rejected')
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Jan 28, 2010
I'm attempting to pass in a collection of dates to a T-SQL 'IN' clause via a date array (see below for how data is collated).
'Workout weeks difference between start and enddate
Dim wksDifference As Integer = CType(DateDiff(DateInterval.WeekOfYear, bookingStartDate, bookingEndDate), Integer)
[code].....
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Mar 26, 2009
I want to pass a comma delemited list of values as a parameter to a query I'm building using the designer in Visual Studio 2008 based on some strongly typed DAL tutorials I was going through. The query is going against a DB2 database. Here's what I want to do:
select * from prices where customer in(?)
It works fine win I pass in 123456 as ?But fails when I pass in '123456' (it is a char field so I don't know why this doesn't work; it must be adding these behind the scenes) or 123456, 123457 or '123456', '123457' I'm adding this page to a portal where all the data access is being done based on the DAL designer model with a BLL that calls it so I wanted to do it this way for consistency.
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Nov 21, 2010
I need to convert the following C# code to VB.NET:
public bool TryGetRewriteMatch(UrlContext url, out RedirectMatch match)
{
// NOTE: Normally this would use regular expression matches, cached database
[Code].....
However, I need to reference Url and ProductID in the function and I don't know how to pass them as parameters or get their values from the original function.
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Apr 22, 2012
I have a bit of a problem. I am currently makeing a webpage that has a few dropdown lists on each page. The purpose of the dropdown lists are to filter the information in a YUI datatable, aswell as eachother's information, eg. a different location will have different commodities etc.
I have made a common function to read the option ID's and values from the DB, but the information can be used in 3 ways. Currently, when the page loads I create a Asp:Placeholder that I load the Dropdown lists in. If the information is requested by Ajax to update a select box, I concatenate a HTML string server side and response.write it. But now my client has requested to have a lookup for if the list in the dropdown box is too long, which I am doing using a YUI modal panel and a YUI grid. I would still like to use the same data fetching subprocedure, but this time I would like to send the data back as a JSON string.
Currently I have boolean flags to signal whether its the pages initial load to create a placeholder, or an update load to make an HTML string, but I would rather like to pass the "information rendering/formatting" subprocedure as a parameter, this eleminating the need for several boolean flags.
My Code
Public Shared Sub LoadCoop(ByRef PlaceHolder As Object, ByVal SearchCriteria As String, ByVal Database As String, ByVal InitialLoad As Boolean)
Dim SqlConnection As New SqlConnection
[code]....
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Feb 16, 2012
I am calling a crystal xi report from a windows form and passing 2 date parameters and a customer name. In some cases this customer name contains '&' eg Brown & Williams
In these cases my report fails and errors. if the name doesn't contain '&' it works. How can I pass the parameter with a & in it ?
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Apr 26, 2011
I created a dataset that is getting data from an access database. Now i would like to go further and make the dataset query accept a parameter from a form datepick value. the query in my table adapter I have changed it as follows to accept a parameter on date1.[code]The code I am using in my form is as below. I get a null reference exception on the second line(Object reference not set to an instance of an object). it seems as if my selectCommand is bringing nothing.[code]
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Jun 2, 2012
I have a bound DataGridView (dgvBuild) that contains data based on a "ProductID" that is derived from selecting the value from a ComboBox. How do I pass the ComboBox Value to the DataAdapter to retrieve records to reload the dgvBuild? Below is the code for theDataAdapter.This is the line that was created when I bound the DataGridView to a DB Table.
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Jun 10, 2011
I need to pass an event as a parameter to a function and I'm wondering if there is any way of doing this.The reason why I need to do this is because I have a sequence of two lines of code that is littered all over my program, where I dynamically remove the handler to an event, then set the handler again. I'm doing this for several different events and event handlers, so I've decided to write a function that does this. As an example, let's say I have a combobox in my code called combobox1, and I have the handler called indexChangedHandler. In several places of my code, I have the following two lines:[code]Now, I don't want to keep on repeating the above two lines of code (or similar) all over my program, so I'm looking for a way to do this:[code]So far, the "evt as Event" part of the argument of the setHandler function is giving an error. Any ideas on the right way to do this will be very welcomed.
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Nov 10, 2010
I need to pass an event as a parameter to a function and I'm wondering if there is any way of doing this.
The reason why I need to do this is because I have a sequence of two lines of code that is littered all over my program, where I dynamically remove the handler to an event, then set the handler again. I'm doing this for several different events and event handlers, so I've decided to write a function that does this.
As an example, let's say I have a combobox in my code called combobox1, and I have the handler called indexChangedHandler. In several places of my code, I have the following two lines:
RemoveHandler combobox1.SelectedIndexChanged, AddressOf indexChangedHandler
AddHandler combobox1.SelectedIndexChanged, AddressOf indexChangedHandler
Now, I don't want to keep on repeating the above two lines of code (or similar) all over my program, so I'm looking for a way to do this:
Private Sub setHandler(evt As Event, hndler As eventhandler)
RemoveHandler evt, hndler
AddHandler evt, hndler
End Sub
so that everywhere where those two lines of code(or similar) occur in my program, I can just replace them with:
setHandler(combobox1.SelectedIndexChanged, AddressOf indexChangedHandler)
So far, the "evt as Event" part of the argument of the setHandler function is giving an error.
P.S I've asked this question on a couple of other forums and keep getting asked why I would want to set the handler immediately after removing it. The reason is because dynamically adding an event handler n-times causes the handler to be executed n-times when the event occurs. To avoid this, i.e to ensure that the handler is executed just once when the event occurs, I first remove the handler each time I want to add the handler dynamically.
You might be asking why the handler would be added several times in the first place... The reason is because I add the handler only after a particular event, say E1, in my form has occured (I add the handler within the handler of event E1). And event E1 can occur several times within my form. If I do not remove the handler each time before adding it again, the handler gets added and thus executed several times.
Whatever the case, the processing occuring within the function is not of ultimate importance to me at this time, but rather just the means of passing an event as a parameter.
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Nov 16, 2010
I'm wondering if this sort of thing is possible in VB.NET.. say I have a routine which accepts an integer array, defined as:
Sub WriteTable(iRows As Integer, arrColumns As Integer())
The arrColumns parameter is an integer array of column widths.
I can pass a value by doing this:
[code]....
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Jan 30, 2010
from the documentation we have this: Multicast Delegate: Represents a multicast delegate; that is, a delegate that can have more than one element in its invocation list.
so am i right to say that Multicast delegate is no different from a normal delegate other than the fact that it has arguments. so System.Action is a 'normal' delegate whereas System.Action(T)(Byval obj as T) is a multicast delegate?
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Jan 8, 2010
How can i cancel the eventhandler, i have a problem with tab browser is that:- i have a set of button image to show the forward and back button which are disable or enable (like IE).Inside my program which are deal with the web_CanGoForwardChanged and web_CanGoBackChanged event.my problem is that if i click on other tab faster than the eventhandler done,i got the wrong image shown on button.how can i stop the eventhandler to prevent the wrong image.
Public Function GetBrowser() As WebBrowser
If TabControl1.SelectedTab IsNot Nothing Then
For Each c As Control In TabControl1.SelectedTab.Controls
If TypeOf (c) Is WebBrowser Then
[code]....
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Aug 27, 2011
I am trying to call a method that started on a background thread on the UI thread calling BeginInvoke and passing in a delegate as follows:
Dispatcher.BeginInvoke(Function() UpdateApplicationDataUI())
to call this method:
Private Sub UpdateApplicationDataUI()
...
End Sub
However, I get an error in the call to BeginInvoke (the UpdateApplicationDataUI portion of the delegate is stating "Expression does not produce a value").
Me.Dispatcher.BeginInvoke(Function() New Action(AddressOf UpdateApplicationDataUI))
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Dec 12, 2009
sample code for passing parameter to crysatl report dynamically in vb.net ...?
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Dec 29, 2008
I wrote vba function in excel and I want to call this function in vb.net with parameter passing.
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Jul 24, 2010
I am getting error when debugging a project. The error is as below,
"FormatException was unhandled
String was not recognized as a valid DateTime."
Highlighting the following line
[code]...
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Jun 30, 2011
Assuming I have the following code that is iterating over controls in a panel setting various control information.Private Sub BindDataFields()
[Code]...
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Nov 1, 2010
Is there a way to pass an optional parameter to a webservice, instead of having to overload the method?If the webservice user is accessing the webservice directly, I want to do ActionA, if the user is accessing the webservice through my web interface, I want to do ActionA + ActionB.
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Aug 12, 2010
Can't seem to figure out why this is not working.
Dim Myspcmd As New SqlCommand("spDataImport", myConnection)
Myspcmd.CommandType = CommandType.StoredProcedure
Myspcmd.Parameters.Add(New SqlParameter("@FileName", Data.SqlDbType.NVarChar, 100)).Direction = ParameterDirection.Input
Myspcmd.Parameters("@FileName").Value = "Import_File.dtsx"
myConnection.Open()
[Code]...
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Nov 2, 2011
I'm calling unmanaged C++ Dll function from VB.Net project by usin dllimport attribute like this;
<DllImport("Injection.dll", CallingConvention:=CallingConvention.Cdecl)> _
Private Shared Sub Injector(ByRef Client As String, ByRef Dll As String)
End Sub
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Sep 9, 2011
I am using following code to connect to my database.
Dim conStr As String = "Data Source=.SQLEXPRESS; ![enter image description here][1]
AttachDbFilename=|DataDirectory|dbTest.mdf;
Integrated Security=True;
User Instance=True"
Dim sqlQry As String = "SELECT * FROM [tblTest] WHERE ([Name] = @Name)"
Dim dAdt As New SqlDataAdapter(sqlQry, conStr)
Dim dSet As New DataSet()
Then filling adapter with
dAdt.Fill(dSet, "tblTest")
And then I can use the data the way I want.
My question is: How to pass the value of parameter that user will give through a text box on my webform.
Dim sqlQry As String = "SELECT * FROM [tblTest] <b>WHERE ([Name] = @Name)
I mean how to pass the parameter value to my query?
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May 1, 2012
Im using a datatable and i am trying to do a insert statement into an oracle database by passing selected values from the datatable to the insert statement via parameters. I'v traced the parameter collection and it has the correct number of parameters to be passed but it is giving me an error saying a value being passed in is null but it is not, during debug you can clearly see the value of the parameter is not null.
Dim FuelInsert As String = "INSERT INTO table (COMPANY, TRAN_DATE, GAS_GALLONS,DSL_GALLONS,DEF_GALLONS,KER_GALLONS,E85_GALLONS,DDS_GALLONS,WDS_GALLONS)" _
+ "VALUES(:Company, :Trans_Date, :Gas_Gallons, sl_Gallons, ef_Gallons, :Ker_Gallons, :E85_Gallons, ds_Gallons, :Wds_Gallons)"
[code]....
I just wanted to know if there was a easier way of creating the parameters or if i am missing something simple that causing the values of the parameters being passed to get mixed up. The code retrieves the values i need and builds the parameter collection of 0-8 nodes which is correct.
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Jun 18, 2011
I want to pass a date as parameter in vb to query the data from the table.If I hardcore the value in the query it works fine for me, but if I pass it as parameter to query, like I am getting the data from edit text and trying to send that as a parameter, this does not work.
SELECT *
FROM VehicleAnalogParamDownload2
WHERE Vapd2_Date between 'From_date.Text' And 'To_Date.Text'
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Aug 12, 2011
I seem to be passing the parameter to the report (I placed the parameter field itself on the report to verify this) but it does grab any information based on this parameter. All of the fields appear with no data but the parameter is showing up correctly.Yes, I have verified that the parameter is in the select statement of the report.The report also is exporting correctly but still without the data.
Below is the code I'm using:
CR Loading
Try
Dim cryRpt As New ReportDocument()
Dim reportPath As String = "MyReport.rpt"
cryRpt.Load(reportPath)
[code]....
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Oct 2, 2009
From what I understand, when you use AddHandler you're not actually calling a Sub, so you can't pass a parameter. I'm confused on what to do though about this. I've just populated a DataGridView and added a button to it in the codebehind. I'm then using an AddHandler to add a click event to the button. So when I get to the click event, I need to be able to access to the datagridview because clicking the button takes data from the datagridview and loads it into excel. What would I do about this. This is my Method where DataGridView was just populated
Dim btn As New Button
btn.Name = dgv.ToString()
btn.Location = New Point(0, 0)
[code]....
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