Grouping A Generic List Via LINQ?
Jun 26, 2011
I need to take a collection and group it via Linq but all the examples I've seen fail in some manner or other with some syntax difference that I can't quite lick.
My collection:
Dim a As New List(Of ProcessAlert)
a.Add(New ProcessAlert("0000112367", "5551110000@txt.att.net", "Alert", 2))
a.Add(New ProcessAlert("0000112367", "5551110000@txt.att.net", "Document", 2))
[Code].....
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Jul 2, 2009
I am trying to learn some VB.NET for my coo-op that starts next week, and for that reason i took my portfolio web site that is on C# and just started to converting it to VB.NET to get familiar with the syntax.
I am sure my problem is simple however i have a hard time solving it. I am trying to grab data with the linq query and then return it as list to bind to the Repeater.I have the following function:
[Code]...
And it would work fine. However if I try to use ToList() in VB.NET i am getting error that it cannot convert it from ling to sql List to the generic list. How do i do this convertion in VB.NET ? or maybe there is another way ?
I am decent when it comes to C# however somewhat lost with the VB.NET syntax.
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Nov 22, 2009
I have a function that works great in C# that I'm converting to VB.Net. I'm having an issue converting the result set to a generic list in VB.net.
The code:
Public Function GetCategories() As List(Of Category)
Dim xmlDoc As XDocument = XDocument.Load("http://my_xml_api_url.com")
Dim categories = (From category In xmlDoc.Descendants("Table") _
Select New Category()).ToList(Of Category)()
Return categories
End Function
The error occurs when convertng the result via .ToList(Of Category)() The error:
Public Function ToList() As System.Collections.Generic.List(Of TSource)' defined in 'System.Linq.Enumerable' is not generic (or has no free type parameters) and so cannot have type arguments.
Category is a simple object I've created, stored in the App_Code directory.
I have the necessary "Imports System.Collections.Generic" reference in the file so I don't see why I can't convert the result set to a generic list.
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May 8, 2009
Dim tenItem = From t In _InvalidFeeList _
From i In ItemCount _
Where t.FeeCode <> i.FeeCode _
[Code]....
I am getting "Can not convert to System.generic.list" error. I look all over for this error and it seem like my code should work for example here
edit: I think i should explain what I'm trying to do here. I want to compare two object list and select the object from the InvalidFeeList if the FeeCode is not equal to the object in ItemCount FeeCode and take the first 10 objects from the InvalidFeeList.
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Feb 5, 2010
I'm having a heck of a time with transforming a simple SQL Query into a LINQ query(using vb btw)
Here is my SQL:
SELECT USRDEFND5
FROM int_gp_employee
GROUP BY USRDEFND5
[Code]...
I've tried a number of different variations of the LINQ. My current statement is:
From b In xmlFile...<row> Group b...<usrdefnd5> By b...<usrdefnd5> INTO group when I foreach through the resulting collection, EVERY line (17000) shows up.
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Jul 7, 2009
I've a large table of Items and I need to organize them by Category, then by Year and then by Month.Item has CategoryID and Dated properties.I got this far:
Dim Items = From Item In DB.Items _
Group By CategoryID = Item.CategoryID _
Into Categories = Group _
Order By CategoryID
But where I put the:
Group By Year = Year(Item.Dated)
and the
Group By Month = Month(Item.Dated)
The final result should be something like this:
For Each Category in Categories
For Each Year in Category.Years
[code].....
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May 25, 2011
I'm completely dense here, but I'm trying to get some stats from a DataTable. One of the columns in the datatable is called "colour".I need to find out how many of each instance of "colour" are in the datatable.
I'm trying:
Dim q = From p In PGWorkingDataTable _
Group p By p("colour") Into Group _
[code].....
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Aug 15, 2011
I have a table called Ordersthe table has many rows but im only interested in two in particular.I want to query the table so it returns the average ordered count of each producti want to know what is the average count of the ordered products, but now in total but per productID instead.
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Nov 17, 2009
I am struggling with a nullable datetime column [DateInsp] in an ASP.NET app which uses SubSonic3, Linq, MS SQL Server 2005.I had this all working when the datetime column [DateInsp] did not allow nulls. A new requirement forced me to set the [DateInsp] column to allow nulls and now I am struggling getting this piece of functionality to work properly again.
Problem 1:I need to first render a dropdown list of the 7 most recent inspection dates for a given inspector (this is a grouped list of the 7 most recent dates for the inspector). Here is the TSQL that I need to convert to Linq syntax:
declare @InspectorID varchar(5)
set @InspectorID = 'GPA'
select top 7 convert(nvarchar(30), [DateInsp], 101) InspectedDate
[code]....
If I can't get this work properly using Linq, BUT I can/could build a stored proc to return the list of dates and throw that into a dropdown. Fair enough. I've been fighting with the Linq syntax?
Problem 2: I need to use the selected date in the dropdown mentioned above to pull the correct records for this inspector and the correct date. Again, this is a nullable datetime field and this is real sticking point for me.
Here was the original Linq syntax that accomplished the requirement before I had to change the datetime field to allow Nulls:
Dim query = (From i In db.IncomingInspections _
Where i.InspectorID = User.Identity.Name _
Group By Key = New With {i.DateInsp} Into Group _
[code]....
For some reason I can't use the .Value property; I get: The member 'Value' is not supported I get: "Incorrect syntax near '<'." if I try to add the date comparison to the where clause too.
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Aug 9, 2010
I have the following table structure. I want to select distinct CustomerId and CustomerName, TotalCost.[code]
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Nov 9, 2011
I'm very new to linq and I'm trying to come up with a linq query against a dataset that will return a max count value based on grouping records.[code]...
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May 24, 2010
I'm having trouble getting my head around converting a traditional SQL aggregate query into a LINQ one. The basic data dump works like so:
Dim result =
(From i As Models.InvoiceDetail In Data.InvoiceDetails.GetAll
Join ih As Models.InvoiceHeader In Data.InvoiceHeaders.GetAll On i.InvoiceHeaderID Equals ih.ID
[CODE].....................
What I need to really be getting out is ih.Period (a value from 1 to 12) and a corresponding aggregate value for i.ExtendedValue. When I try to Group ih I get errors about i being out of scope/context.
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Apr 24, 2012
I've got the below, where I'm grouping a collection by a propery, then wanting to access the properties of my group. Problem I have is with the anonymous typing. Because of option strict I have to give an explicit type but I can't work out what the type should be. The below doesn't compile because t.HeadAccountKey isn't a value (as t has a type of object). So either I need do some casting or my linq selector is wrong,
[Code]....
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Jun 30, 2011
I am trying to create a list of a generic type in vb.net 2.0 framework.
This is the generic type definition:
Public Class GenericParamMap(Of T)
Public Sub New(ByVal pParamName As String, ByVal pPropValue As T)
mParamName = pParamName
[Code]....
The compiler does not allow a "T" in the method's parameter because it's not defined, but I'm not sure how or where to define it. I thought it was okay to have a generic method definition.
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Oct 1, 2009
I'm looping all the properties in an object via reflection:
For Each p As PropertyInfo In values.[GetType]().GetProperties()
If p.CanRead Then
'Do stuff
End If
Next
how to determine whether the property in question is a generic List(Of T)? If it is I need to loop the list itself.
I've experimented with GetType and TypeOf but have not managed to get anything working.
To clarify, I want to keep this generic. I do not want to specify the type of T, I need to loop the list items and call the ToString method on each item. T could be one of a number of different types (application specific reference types). Is it possible to do this without specifying types?
(VB.NET 2005 with .Net 2.0)
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Mar 23, 2011
Public Class notifierMain
Public Class Contacts
Inherits List(Of row)
Public Sub New()
[code]....
When I debug this winforms application I get curType = "notifier.notifierMain+Contacts+row" I want to the Validate function to know it is in MyContacts. How do I do this?
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May 3, 2012
i have issue returning a list in a web method. here is the code
<WebMethod()> _
Public Function getTags(para_parents As String) As List(Of getTypeDetailsByParentName_Result)()
Dim context As New PPEntities
[code]....
the error is
Value of type 'System.Collections.Generic.List(Of SaftyonRoad.getTypeDetailsByParentName_Result)' cannot be converted to '1-dimensional array of System.Collections.Generic.List(Of SaftyonRoad.getTypeDetailsByParentName_Result)'
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Apr 7, 2011
it seems always at this time I cant figure out how to do something maybe it has something to do with lunchtime.
Im having trouble using a method that is defined by an outside company
This is a link to their integration guide:
[URL]
This is their documentation for the class Im trying to use
OrderQueryWebService Class
This class is for SID in particular and is made for use with the notification methods. This is for the Order Query Web Service specifically, allowing clients to return the status of transactions for their merchant, whenever they want to.
Methods
/ <summary>
/ Pass through the variables required and receive a list of Transaction
objects showing transaction status
[Code].....
The MerchantCode, the MerchantUsername, the MerchantPassword are all good the List is a custom type called SetComHash.Transaction
Everytime I try adding a string to the list such as the transactionNumber and some other values it gives me a type error:
"Value of type string cannot be converted to 'SetcomHash.Transaction'
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Sep 8, 2010
I have pairs of controls: immagebox + textbox = one pair.I want these to show up in a single column grid/tabular format.Each cell contains one image/text pair.I want this grid to scroll because the number of pairs is dynamic depending on a user selection.I suppose I will be adding these controls in code at runtime when the user makes his/her selection.
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Jan 2, 2010
As I am beginner in LINQ, I have small problems. I have dictionary of Char and Long, and I would like to use LINQ to retrieve Char with highest Long Value. I saw some C# samples, which look pretty easy, but I can't achieve such expression in VB.Here are two expressions, and I don't think they are most efficient possible.
[Code]...
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Oct 29, 2010
What would be the fastest way to sort a list that contains a list of objects, based upon another list? An example follows:Say I have multiple lists of employees. Each individual list has a common property value, say "Department". So I have a list of employees, in one list they all have the department string value of "Sales". In another list all the objects have a department value of "Finance". These lists of employees are then contained in a list which holds them all.
I have a second list, which should drives the sort order of the employee lists. The second list simply contains a list of strings like, "Finance", "Sales", "IT" and so on. I'd like my lists of customers to be sorted in the order of "Finance", "Sales", etc.I'm using VB.NET in .NET 2.0
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Nov 4, 2010
I would like to implement a generic Linq query on a DataGridView.DataSource to retreive a row whith an idField. I did search MSDN, StackOverflow, etc... but didn't quite find what I'm looking for. how I could implement it ?
This is the non-generic code, but I would like to make it work whatever the type of the DataSource is (as long as it implements IEnumerable I guess) and the name and type of the key field.
Dim query = (From note In notesList _
Where note.IdNote = mIdNoteSelectionne _
Select note).FirstOrDefault()
Dim ancienIndex As Integer = notesList.IndexOf(query)
noteList is a List(Of Note), Note is a simple entity class I created, with just members and properties
This is in VB, but feel free to send some C# code, I'll translate it.
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May 14, 2012
I wrote the following generic LINQ extension for calculating weighted average in Visual Basic 2010:
<Extension()>
Function WeightedAverage(Of T)(ByVal source As IEnumerable(Of T),
ByVal selectorValue As Func(Of T, Integer),
ByVal selectorWeight As Func(Of T, Integer)) As Double
Dim weightedValueSum As Double
Dim weightSum As Integer
[Code] .....
How can I call this function as an Aggregate function of another LINQ query? I tried it in the following way:
Dim q1 = From jd In oContext.JobDatas
Where jd.Year = 2011
Select jd
Dim q2 = Aggregate num In q1 Into WeightedAverage(num.AvSalary, num.NumPosHolder)
The Visual Basic 2010 editor is telling me that the second query (q2) of the following code is not valid statement. On the comma between the first an second argument it's saying: ")" required.
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Nov 27, 2009
I have been writing same code for insert, update, delete with LINQ over and over again. I want to have some sort of generic function for Insert, Update, Delete operation. I read a post here like the following :
public static void Insert<T>(T entity) where T : class
{
using (OrcasDB database = new OrcasDB())
[code].....
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Oct 22, 2009
This is really a continuation from my earlier post. I've never worked with this datatype/collection (system.collection.generic.Ienumerable) before so I'm struggling to declare the query globally so I can reference the results within other sub routines/functions. I also am struggling to convert it to other types.how I can convert the collection of xml elements/system.collection.generic.Ienumerable into an xmltextreader (I know I will have to change the query below as it select the value of the node and not the node itself) I imagine by converting the query result to system.IO.stream My first port of call was MSDN but I find the material very difficult to understand for this particular subject.
[Code]...
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Jan 5, 2011
Dim x = GetType(List(Of )) 'valid statement
Dim list As New List(Of String)
Now I want to see if list is a List(Of T) variable: Dim isList = TypeOf list Is List(Of ) On the last line I get a compile error: "Type Expected". Is there any cheap-performance TypeOf operator alternative for generics?
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Mar 12, 2009
I have converted c# .cs to vb:= I have 6 errors on:
Red "List" says Too few type arguments to system.Collections.Generic.List(Of T)'
Orange "Calendar" says Value of type 'System.Windows.Forms.Control.ControlCollection' cannot be converted to 'Form1.Kobush.Windows.Forms.Appointment'.
[code]....
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Oct 13, 2011
i m getting a collection of data in list's object. And from this list i want to get the maximum id.`
Dim objinfo As List(Of AlbumInfo) = objPhotos.GetPhotos_Alb_ID(Me.ModuleId, hdd_AlbID.Value)
Dim Photo_Image As String = ""
Dim str As String = Photo_Image & fu_Photo.PostedFile.FileName.Substrng(fu_Photo.PostedFile.FileName.LastIndexOf("."))
[code]....
this returns the "0"th positions id from Convert.ToString(objinfo.Item("0").Photo_Id + 1)but i want to get the last item's id.
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Jan 5, 2011
i have list of string like this :
Dim totalPrice As New List(Of Integer)
how can i get sum of column(0) (C# or VB) ?
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Jan 17, 2011
<div class=PhorumReadBodyText>Hi, I have a problem with adding of items to generic list, problem is when I insert 1. item to the list, everithing is ok, but if I insert second item, first and second has same values.
code looks like that (asp.net 4.0): </div> <div class=PhorumReadBodyText> </div> <div class=PhorumReadBodyText>Partial Class _Default
Inherits System.Web.UI.Page
[Code]...
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