I have a lambda function that I can assign to a field and pass it to a sub routine, but cannot assign to a property. My field is defined as follows:
Public Delegate Sub SubDelegate()
Private pDeleteFunction As Func(Of BookCaseRow, SubDelegate)
[code].....
I'm trying to create a generic function to build a Linq expression from a list of Telerik grid filters. I'm trying to stay clear of dynamic Linq. Because I don't know the type that I'm building the expression for, I'm attempting to use reflection in the lambda functions to refer to a property, but after applying the fix suggested by @JaredPar I get the error, "The LINQ expression node type 'Invoke' is not supported in LINQ to Entities." Is there any way around this? here is my code:
Public Shared Function buildRadFilter(Of T)(ByVal filterExpression As List(Of GridFilterExpression)) As Expressions.Expression(Of Func(Of T, Boolean))
Dim returnPred = PredicateBuilder.True(Of T)()
[Code]....
Is it possible to shorten the following function to a lambda expression?Or (to do the trick by myself) what is the best and most understandable for beginners tutorial for lambda in vb.net?[code]
View 2 RepliesI use the following VB code to execute a scalar function on my sql server:
cmd.CommandText = "[STFRA].[dbo].MyScalarFunc"
cmd.Parameters.Add("@Fastener", SqlDbType.Int)
cmd.Parameters("@Fastener").Value = 4148
[code].....
I had a problem (which is now fixed) but I've no idea why.I have an Ajax AutoCompleteExtender with a WebService method to populate like <WebMethod()> _
Public Shared Function populateACE(prefixText As String) As List(Of String) However this didn't work - I put a breakpoint in, and it didn't even get hit. However... <WebMethod()> _ Public Function populateACE(prefixText As String) As List(Of String) does work (the only difference being not Shared).
Fair enough, but why? If you have an instance of a class then you can access Shared methods of it; if you don't have an instance of a class then you can access Shared methods of it. So what is going on behind the scenes?
I have this function that maps a IDataReader to a class. It is obviously written in C#. My co-worker wants to use the same method in his code, but he is writing in VB.net. Basically I am having difficulty rewriting this due to the Lambda expressions used in C#. He is running .Net 3.5.
[Code]...
I have a problem with VB9 and Moq.I need to call a verify on a Sub. Like so:logger.Verify(Function(x) x.Log, Times.AtLeastOnce)And my logger looks like this:
Public Interface ILogger
Sub Log()
End Interface
[code].....
I need help and wondering if you can help me to get my first project...it's a hobby and wondering if you can get me code for this so i can see how it does it* Evaluate( ) Prints the evaluation of the hand to the evaluation Label.
o If IsFlush( ), prints "flush; "
o calls SetPipArray( )
o Uses a For Loop to go through pipArray. For each element, uses a Select Case statement to
[code]....
I get the following string expression provided:"ChildObject.FullName" ...where ChildObject is an instance property on the MyObject1 type.ChildObject has a property named "FullName" and I want to sort a collection of type "MyObject1" based on this child properties "FullName" value.
I can do this all day long on properties directly on MyObject1 but I run into 2 challanges when doing it on a child instance and I can't get all the pieces working. The main 2 challanges are:
MyObject1 has a few different child property types so I can't hardcode the type for ChildObject. The string could be of any type.The sort expression is a String and not a known type.Above the value returned from the last line in the expression (if I run the code outsode the OrderBy method, does provide me the 'FullName' information I need. So the code must be close, but it still does not work.
Any ideas on how I can accomplish this? What I am trying to prevent is hardcoding a series of 'If' blocks on the child's type to then hardcode in its type to the sort or OrderBy method.
Should I be concerned about the performance of the Compile method here?[code]...
The reason I want the lambda expression is because I want that function to be able to get all the way through LINQ-to-SQL to be converted to SQL. The reason I want the direct version is because I have other code that I want to validate individual serial numbers before submitting changes. And I fear that GetValidSerialNumbers.Contains(serialNumber) will execute a more-complex-than-necesssary query.
I'm trying to sort a list of string, which (each item) consists of a word followed by a space, then a number. I want to sort first alphabetically by the word, then numerically by the number. I tried something like this:
wordList = wordList.OrderBy(Function(x, y) CStr(x.Split(" "c)(0)).CompareTo(CStr(y.Split(" "c)(0)))).ThenBy(CInt(x.Split(" "c)(1)).CompareTo(CInt(y.Split(" "c)(1))))
I am trying to pass a lambda function to Linq's orderby and cannot get it to work.
The relevant code is:
Dim myordering = Function(m) m.Count
If isAlphaOrder Then
myOrdering = Function(m) m.Key 'Order by Alphabet
[Code].....
In on a section of my book about classes and properties. In this example, the author is attempting to show how you can validate a value passed to the property before setting the property. Looks like so far in this book, a couple of things have slipped past the editor, and I think this might be another one...Here's the example:
[Code]...
I have the below C# Lambda function and I need to convert it to a VB.Net code. I tried many times but I couldn't convert it the right way. [code]...
View 10 RepliesI'm currently working with a client's VB.Net code, which was developed for them by a small development shop a few years ago and which they purchased and have been maintaining and uprgrading since. This client's primary developer is out on indefinite (likely permanent) medical leave and I'm now filling in until they bring in a full timer (as I'm a contractor here). My current task is to add some functionality to a the VB.Net code they purchased. I'm finding practices and techniques in the code that absolutely baffle me and can't make the code do what I want. I'm starting to wonder if it's me and was hoping to get some thoughts on the code I've encountered.
For example: Setting a variable to accept the result of a function by calling the function with many parameters, clearing the parameters in the function, setting them to some value, calling another function with those new values, then never using the values returned by the functions. I'll add a code snippet in the first comment since this is already getting long.
I'm trying to use a nested multi-line lambda Function in VB.NET and am getting an error. Here's what my code looks like:
cartItems = cartItems.Select(Function(ci) New With {.CartItem = ci, .Discount = discountItems.FirstOrDefault(Function(di) di.SKU = ci.SKU)})
.Select(Function(k)
If k.Discount Is Not Nothing Then
[code]....
Im hearing about this, can someone explain it to me or please show some basic code of Lambda with explanation.
View 2 RepliesI have the following property in a class:
[Code]....
The problem is that when I try to set the property like this: myClass.Language = "English" The property is set to "English" and not to "<![CDATA[English]]>" which is what I want. What is the reason for that and how can I fix it? When placing a break point on End Set and use the Watch window to inspect the value of _Language after setting the property to "English" it remains "English" and doesn't change.
Given a simple class like this:
Public Class clsOB
Implements System.ComponentModel.INotifyPropertyChanged
Private _Frequency As Double
Private _Value As Double
Public Event PropertyChanged(ByVal sender As Object, ByVal e As
[Code] .....
And then I'd like to do something like this:
Dim
o As
New
clsOB(50, 30)
o = 31
I am converting a 1.1 .NET web app to 3.5, and I've run into a bit of a jam.
One web control has a Property that sets the page title label on that web control.
End Property
When a page with the web control was loaded before, it would set the Property to a given string, like in ucHeader.PageTitle = "This is a string." Now, if I don't remove the lblPageTitle.Text = Value, I get a NullReference Exception.
I'm new to classes. In my Who wants to be a Millionaire application, I have a Lifeline class and I create three instances of it - FF, PAF and ATA (50/50, Phone a Friend and Ask the Audience). Something I do with a lifeline is put a cross over its logo, hence the need for a centrepoint property, which marks the centre of the cross on a form.
Public Class Lifeline
Private ptCentrePoint As Point
Public Property CentrePoint() As Point
Get
CentrePoint = ptCentrePoint
[Code] .....
What happens is that at the "Call Form2.DrawCross(Form2.CentrePoint)" line, the tooltip shows that the FF object's centrepoint property isn't set (as I thought it would be by " FF.CentrePoint = tmpPoint").
I have this simple code,
Protected Sub grdSearch_SelectedIndexChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles grdSearch.SelectedIndexChanged
TimeOff.Where = "UserName=""" & grdSearch.SelectedValue & """"
End Sub
Doing so causes this error, 'UserName' could not be resolved in the current scope or context. Make sure that all referenced variables are in scope, that required schemas are loaded, and that namespaces are referenced correctly. Near simple identifier, line 6, column 1.
The datasource works fine before the where property is set.Update: I found the issue but I still don't get it.Adding it. in the where clause solves the issue. Like this,
TimeOff.Where = "it.UserName=""" & grdSearch.SelectedValue & """"
I am using a user control using vb.net. It include the program to retrieve the values from database while giving the paramers. When I set the property from my main program i am getting an error "Invalid attempt to call Read when reader is closed." When i gone to the online help i got the message as follows "System.InvalidOperationException (.NET Framework 4)The exception that is thrown when a method call is invalid for the object's current state. InvalidOperationException is used in cases when the failure to invoke a method is caused by reasons other than invalid arguments. For example, InvalidOperationException is thrown by IEnumerator.MoveNext if objects of a collection are modified after the enumerator is created, or ResourceSet.GetString if the resource set is closed before the method call is made. If the method invocation failure is due to invalid arguments, then ArgumentException or one of its derived classes, ArgumentNullException or ArgumentOutOfRangeException, should be thrown instead.[code]
View 1 RepliesI am programatically creating instance of usercontrol as shown below
[code]...
I have two public properties in my usercontorl like clerkName and RespName. How can I set those values in the above code. Intellisense is not showing ClerkName and respName Properties.
i want to set autocomplete textbox, but if multiline property of textbox is true, i can't do it.
View 6 RepliesI'm reading in a configuration file which is simply a txt file that configures my Com port and sets some directories. It's basically for the end user to set the interface. I want to give the user the ability to change backcolor properties on my NumbericUpDown property. So when I read in the Config.txt file the end user can change coloring on the General Form. In this case the NumbericUpDown. How to assign a variable for color from my string (from my txt file) that I read in.
View 5 RepliesIm currently debugging my application to found out why it's running a bit slow, when I put breakpoint where i populate one of the application combobox it's run fast but after i populate it and when I'm trying to set the its selectedindex to zero the program halt for about 2 second.. this is the line where the program get stuck for 2 seconds:
[code]...
I am creating a customised version of the ListView control and there are several of the properties that a ListView has that I would like to be set to a different value to the ListView default when a user goes to use my user control.
From what I've found there seems to be a number of people suggesting just set them in the constructor, but to the best of my knowledge that would just mean that the user would not be able to change the properties in the PropertyGrid in the VS IDE.I assume this is probably something extremely simple that I have overlooked.
I have a single form that I would like to move across the screen with my VB program. Of course it's simple to set the location X and Y property for compile time using the properties tab, but I want the form to move as the program runschanging the coordinates within a for-next loop.I can easily get the X and Y coordinates of the form within my program by using X = me.location where X has been dimmed as type point.console.writeline(X) will appear as {X=20, Y=40}. for example
View 2 Replies.From = New MailAddress("Me@MySite.com", "Big Mike")This does not;
Dim AddressFrom As String = "Me@MySite.com"
Dim FromDisplayName As String = "Big Mike"
.From = New MailAddress(AddressFrom , FromDisplayName)
I receive the error; The specified string is not in the form required for an e-mail address.I would REALLY like to use variables here so that I can read these two pieces of data from My.Settings. I've been searching for the answer for hours and I'm stumped.