I'm trying to sort a IQueryable dynamicaly.
Dim activities =From a In db.VW_Activities Select a
activities = activities.OrderBy(Function(a)
New ActivityComparer(SortFields(0).Sort))
definition of SortFields:
[Code]...
I have a list of keys and values that I would like sorted by key via a custom Comparer(Of T). I tried using a SortedDictionary, but kept getting incorrect results because it used the comparer to see if the items were the same. For example calling SortedDictionary.ContainsKey() would return false, even though it did contain the key.
When I stepped through the code after calling ContainsKey(), it would go to the comparer.Compare(x, y) function. It would then only compare against a few of the keys in the dicionary, and somehow skip the matching item (which I ensured did exist). I take it that this is some sort of optimization, where some items are skipped depending on what is returned by the comparer.Compare() function? Is it possible to have a dictionary that only uses the comparer for sorting? EDIT: I am using a Type object for the dictionary's key
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View 4 RepliesI have a two-column ListView linked to a Datapager. The ListView lists all files of a particular type in a particular directory, so the data source is an ArrayList of type FileInfo. Consequently, I had to create a Comparer class to use in the ArrayList.Sort method.
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I have a ListView (GridView) that I want to sort by 2 columns, so if 2+ items have the same value in Column 1, it sorts by Column 2. Pretty easy. But empty strings show up at the top when sorting A-Z. I'd like to move them to the bottom. I made a comparer (IComparer) that takes care of this, but I'm not sure how to use it.[code]...
View 1 RepliesI'm flummoxed I'm using VB.Net, Linq, and a DataContext. My DataContext contains a table 'transactions'.
I first declare an IQueryable(Of transaction) and assign it to nothing. I build a predicate in a foreach loop and use a transactions.Where(predicate) to assign the IQueryable a value. If I do an IQueryable.ToList(), I get a number of items in the collection.
However, on the next iteration of the loop, the IQueryable.ToList() gives me 0 items.This is driving me crazy. I tried to use the LINQ to SQL Debug Visualizer with VS2010, (I recompiled the 2008 version with the new reference) but no dice - I can't see the SQl generated or what's inside the IQueryable.
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I know how to select items from an array with LINQ, but what I can't figure out how to do is access a database using an IQueryable. I connected the database to my project, added two classes from the database to the "LINQ to SQL" .dbml file and saved it. In my programming assignment, I am not supposed to create a data source (table thing) to display the data, but update my own interface manually. In order to do it, I was told to instantiate this:
Private dogs As System.Linq.IQueryable(Of Dog)
(Dog is a class that I added to my .dbml file from the database file)Also, I am told it involves using a method
.AsEnumerable.ElementAt(index As Integer)
So...numeric sorts. Do I really need to write a custom comparer to make a listbox full of numbers sort itself like:
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I'm new to Linq, what's the syntax for orderby in VB? [code]Select distinct state from zipcodes order by State
View 2 RepliesI am currently reading Pro LINQ c# 2008, and in page 87 the guy says OrderBy and OrderByDescending are stable. But he says exactly the opposite in page 96. It looks to me as he is referring to exactly the same functions, so I don't get it. Are they stable or not?
View 2 RepliesI have a grid view with a lot of columns, all need to be sorted on. I have seen a few snippets out there, but I cannot get any of them to work with my example. Here is what I have so far.
Protected Sub gvSearch_OnSorting(ByVal sender As Object, _
ByVal e As GridViewSortEventArgs)
If Not Session("sort") Is Nothing Then
[code].....
m_ListOfsAllFields.OrderBy(Function(x) x.DisplayOrder)
here I have DisplayOrder = 0 for 2 fields, so orderby is messing up and not ordering properly. How can I use orderby to order this collection?
I've got the following to sort entities by their job position. The desired order ist defined in another array. In C# this code works:[code]However I will have to convert this to VB.net. I read the equivalent would be something like the following:[code]This does not compile, gives me "Expression expected" right after the Function(x). What am I doing wrong?
View 1 RepliesI'm having a problem implementing Scott G's Dynamic.vb extension at [URL] in my vb solution. I've searched StackOverflow (80+ Q&As) and numerous other sites without much luck. I'm using VS 2010.I've included Dynamic.vb in a problem with no root namespace, and then added a reference to that project in my main one. I'm getting intellisense for 4 overloads (rather than 2) so I'm pretty certain that the extension is in scope.I was having a tough time with clauses, especially the OrderBy as Scott demonstrated. If I simply pass a string as Scott's VB example did I get the error "Overload resolution failed because no accessible 'OrderBy' can be called with these arguments."
The line of code is:
Dim FilteredComponentList = From Component As MX.Component In ComponentList.AsQueryable _
.OrderBy("Name")
So I found other references that stated to pass a Lambda expression. So I tried this and at least I get no error, even if the sort function still doesn't seem to work. Here is the code that compiles and executes.
Private Sub SortByColumn()
If Not cmbComponentFilter.SelectedItem.ToString = "All" Then
Dim FilteredComponentList = From Component As MX.Component In ComponentList.AsQueryable _
[code]....
When I interrogate the dgvComponents.Columns(e.ColumnIndex).Name it gives the objects property I wish to sort by, but the sort still isn't working. I'm concerned why I can't get Scott's implementation to work, but I've heard his keynotes and read his blogs, so I'm guessing the problem lies with my implementation.
I'd like either to work but need to understand why as well. Why doesn't passing a string work? Isn't the PARAMARRAY declared in the function optional?
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
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I'm getting my feet wet with Lambda expressions and it's rather overwhelming.I have a UserPrincipal object called SelectedUser. I wish to get a sorted list of the user's groups This is what I have so far but when I include that code my application's form flashes a few times and closes! Also, what is the significance of the "r" in the "Return From r" statement?
Dim SortedGroups As PrincipalSearchResult(Of Principal) = GetSortedGroups(Me.SelectedUser.GetGroups())
Private Function GetSortedGroups(ByVal psp As PrincipalSearchResult(Of Principal)) As PrincipalSearchResult(Of Principal)
Return From r In psp.OrderBy(Function(t) t.Name)
End Function
I have a method in a webservice that has parameter with which users can decide how they want to order their results. This is a List(Of String) with the names of the fields in the order they want to sort them. I know I can normally order on multiple columns by doing the following
Dim test = Bars.OrderBy(Function(x) x.Foo) _
.ThenBy(Function(x) x.Bar) _
.ThenBy(Function(x) x.Test)
However in this case this won't work since I can't chain the ThenBy function because I'm adding the sorting orders in a loop. To use ThenBy I need an IOrderedQueryable collection. This is how I would want it to work
Dim sortColumns = {"Foo", "Bar", "Test"}
Dim query = From b in Bars
For each column in sortColumns
Select Case column
Case "Foo"
query = query.Orderby(Function(x) x.Foo)
[Code] .....
I need to return an a generic list in the correct order for my project, and I'm getting InvalidCastException errors. Here is the code:
Dim lDt As List(Of Comment) = RemapCommentsForE1(so.CommentList). _
OrderBy(Function(x) x.CreateDate.Value). _
ThenBy(Function(x) x.Sequence). _
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I've got a number of columns the user can sort by (Name, County, Active) and that's easy but messy. Looks something like this...
Select Case e.SortExpression
Case "Name"
If (isDescending) Then
[CODE]...
What I would LIKE to do, is something more ... like this
Private Function SortThatList(ByVal listOfStuff As List(Of Stuff), ByVal isDescending As Boolean, ByVal expression As Func(Of Stuff)) As List(Of Stuff)
If (isDescending) Then
[CODE]...
But it doesn't like the datatype (Of TKey) ... I've tired Func(Of stuff, boolean) (got something in c# that works nicely like that) but can't seem to get this one to do what I want.What's the magic syntax?
I am getting an error when I code a Sub for btnDelete_Click...and it's coming from my FormActionHandler. Here is the code in my FormActionHandler:
Public Shared Function DeleteVendor(ByVal oldVendor As Vendor, ByVal newVendor As Vendor) As Boolean
Dim aServiceFactory As PayableAppServiceFactory = PayableAppServiceFactory.GetInstance()
Dim aVendorService As VendorService = aServiceFactory.GetServiceInstance(PayableAppServiceFactory.SERVICE_NAME.Vendor)
Return aVendorService.DeleteVendor(oldVendor, newVendor)
End Function
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I have a combo box bound to a datasource. I need to change one combo box (of many) to order the items in descending order.I'm guessing I could order the collection in the dataset, but that will mean all my combo boxes will be reordered?
View 2 RepliesI have a databound Datagridview. The DGV is bound to a datatable of a strongly typed DataSet created using the wizard. Is there any way to re order the columns before displaying them eg: the Columns are displayed in the DGV in this other Col4, Col6, Col3, Col1,Col5, Col2
But I want to it to show as Col1, Col2, col3, Col4, Col5, Col6?
I realise that the display order followed the Column order in the database table and by extension, the datatable. I have re-arranged the columns in the Database but the Datatable still retains the old order.
I'm trying to get datetime value but here is issue with nullable datetype.
Public Function GetDate(ByVal kodg As Integer) As DateTime
Dim g = From dt In db.xDates _
Join f In db.xGrafiks On dt.КодД Equals f.DateKod _
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I am new to EF Linq and I have been struggling with this query for a few days. From reading this forum, I have managed to get this far:
Dim noPic = (From f In myEntities.FriendLists
Where (f.UserID = Profile.ID)
Select f.FriendID).Except(From g In myEntities.GuestLists
Where g.EventID = _id
Select g.FriendID)
[Code]...
I am trying to get everybody from the FriendList who is not already on the GuestList to display in a Repeater control. After reading the forum I was able to append .First() to noPic at the myNoPic declaration and finally get a result but that only gave me the first element. Does anybody have any advice on how to accomplish this?
This is giving me a headache. I have this link query here that grabs an ID
Dim mclassID = From x In db.SchoolClasses Where x.VisitDateID = _visitdateID Select x.ClassID And then later on I have this linq query
ViewData("Staff") = From t In db.Staffs Where t.ClassID = mclassID Select t
I've tried quite a few things but to no avail. I've attempted casting, converting, Is operand, etc.
This might not be so 'VB' as it is 'SQL using VB' I have an application with a built in MS Access DB. I have a table that has a column full of integers, I shoot the DB a SQL "order by 'column name' " string and it returns the table ordered by my column of integers.BUT it returns them like this, and I want them like this
0 6
1 5
2 4
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How do I get the OrderBY to do a descending list starting with the highest number?
I'm working on the exercise page 73 (VB 2010 in 24 hours). It's basically a form with 2 text boxes, 2 text labels and a command button. It's really simple and uses this loop to cycle through the items, and tell me the name of them in a Messagebox
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When i try to install the Visual Studio 6.0 in Vista , am getting following error message,"setup was unable to create a DCOM user account in order to register 'C:programs FilesMicrosoft Visual StudioCommonToolsVS-Ent98Vanalyzrvalec.exe"
View 1 RepliesI have to order a table following a logical order but I cannot find the appropriate ORDER BY clause.To simplify I have 2 fields field1 and field2
1 record : field1 contains �2� and field2 contains �1�
2 record : field1 contains �1� and field2 contains �2�
3 record : field1 contains �2� and field2 contains �2�
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I'm having a few problems converting some code into VB.NET from C#. Most of the translating is done, but I am getting errors when I try to run my code, and I can't figure out what is causing them. Here is the Sub I translated.
Public Sub CreateWidget()
Dim blue As LCDColor
blue.Red = 0
blue.Green = 0
[code]....
The error I receive on this line ("vision.Widgets.CreateWidget(wg1)") reads "In order to evaluate an indexed property, the property must be qualified and the arguments must be explicitly supplied by the user."