Linq Not Working After .Net 2.0 To 3.5?
Jan 15, 2012
I started developing an application several weeks ago and decided today that I may want to use LINQ. So I changed my project from .NET Framework 2.0 to 3.5 and restarted the program. However, I can not get the most basic LINQ statement to work. I thought it was my code until I started a blank .NET 3.5 project and inserted the basic code (below) which worked without issue. So I then started another .NET 2.0 project and inserted the code (which I knew wouldn't work) and the errors are the same as the project that I converted. So next I converted this new .NET 2.0 to 3.5 and the code still doesn't work. So migrating from 2.0 to 3.5 isn't working for LINQ.
My question is: If one changes from a .NET 2.0 to a .NET 3.5 how do they get LINQ to work properly?
[Code]...
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Apr 20, 2010
I just upgraded a project from VB 2008 to VB 2010. Before, the project did not use LINQ. I have started implementing it. So, I have updated the target framework from 2.0 to 3.5, and added a reference to System.Core, and imported the namespace System.LINQ to the entire project and also imported System.Data.LINQ into the form I'm working with (because it was not available in the list for Imported Namespaces in the references tab).
It's not throwing any errors now, but my IntelliSense is not working for LINQ stuff.
For example... I write this:
[CODE]....................
Then, if I type S. on the next line, the IntelliSense doesn't grab what it should for S (Only get Equals, GetHashCode, GetType, ReferenceEquals, and ToString, instead of the options I should get like Count, First, FirstOrDefault, etc...). If I Type S.First. then its the same thing, no IntelliSense that lists the available fields for S, just the standard options (Equals, GetHashCode, GetType, ReferenceEquals, and ToString). I should be seeing my column names in my table when I type S.FirstOrDefault.
So any ideas what is going on? When I type the code, for example, MessageBox.Show(S.FirstOrDefault.FirstName), it works perfectly. But it doesn't change the casing of the text (so it would read s.firstordefault.firstname) and no intellisense while doing it. But no errors. BTW - Everything works perfectly when creating a NEW VS 2010 application, it's just my projects upgraded from Visual Basic 2008 that have this issue.
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Sep 20, 2011
user.fld_usr_name is a string with the value random name user is an object that is given as a parameter
ByVal user As GUser
this is the linq query that doesn't work
Dim result = (From usr In users Where usr.Name.Contains(user.fld_usr_name) Select usr).ToList()
this is the one that works
Dim result = (From usr In users Where usr.Name.Contains("random name") Select usr).ToList()
this is the error
Object reference not set to an instance of an object.
I am using this in Linq to Active Directory library which probably means it's linq to entities I've tried everything?
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Feb 13, 2010
What happend to my Intellisense?When I type a line like this ...
Dim users = (From u In Membership.GetAllUsers Select u.UserName)
I get (almost) no Intellisense when I get to the Select u. part. Only Equals, GetHashCode, GetType, ReferenceEquals and ToString appears. Not "UserName" and the other relevant propeties of the MembershipUser class.The code compiles and works just fine.
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Apr 14, 2010
Using the following code:
Private Sub MakeMeSomeXmlBeforeRyanGetsAngry()
Dim db As New MyDBDataContext
Dim customer = From c In db.Customers Select c
[code]....
I am attempting to serialize my linq collection of customers. But it keeps throwing
Type 'System.Data.Linq.DataQuery`1[MyDB.Customer]' cannot be serialized. Consider marking it with the DataContractAttribute attribute, and marking all of its members you want serialized with the DataMemberAttribute attribute. See the Microsoft .NET Framework documentation for other supported types. My issue is that I have already marked the dbml Serialization Mode to UniDirectional and when I check the dbml codebehind all of the DataContract()> and DataMember()> elements are there. I have tried adding various dataloadoptions and setting deferredloading to false, but no luck.
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May 11, 2009
I use the following statement to position which row to update;
Dim salonToUpdate = (From r In db.Salons _
Where r.StoreID = storeID _
Select r).Single()
If fileDate = #1/1/1900# OrElse fileDate = Nothing Then
SalonToUpdate.LastDownLoadDate = TableDate
[Code] .....
I've double checked to make sure none of the dates are invalid or null, but when the bolded statement executes, the following sql runs through the trace:
exec sp_executesql N'UPDATE [dbo].[Salons]
SET [LastDownLoadDate] = @p0
WHERE 0 = 1',N'@p0 datetime',@p0='2008-01-04 00:00:00:000'
Of course it's going to fail if LINQ is passing in where 0=1 every time. Shouldn't it be using some unique row identifier, (in my case, the salon id), to update the specific row?
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May 15, 2012
I have this code to get images width and height from header file without full loading the image..I convert it automatically from C# to VB.NET by [url]....The source C# code here:http:[url]....
Now I need this code to work with .net framework 2.The code doesn't work after converting even with .NET 3.5
Imports System.Collections.Generic
Imports System.Drawing
Imports System.IO[code]..........
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Sep 14, 2010
The below query fails with Null Reference Exception when there are elements in BOMIDs where MatID property is nothing.I thought the 'x.MatID isnot Nothing AndAlso' would prevent the x.MatID.Process part of the where from being executed. There are a couple elements in the BOMIDs collection that where MatID is nothing.
From x In BOMIDs _
Group Join y As PurchasedProcess In SpecialProcesses _
On x.MatID.PurchasedProcess Equals y.Name _
Into G = Group _
[code]....
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Sep 26, 2011
I am trying to get Linq going on. I have a CustomClass named Ordr with the properties OrderID, EmployeeID, _ShipRegion
I do a simple query:
Dim query = From c In dbcontext.Orders _
Where c.EmployeeID = 2
Select New Ordr With { _
.OrderID = c.OrderID, _
.EmployeeID = c.EmployeeID, _
.Shipregion = c.ShipRegion}
Then I bind this query to a DataGridView:
DataGridView1.DataSource = query
Now, when I try to save any changes with dbcontext.SaveChanges() no changes are saved. OrderID is the primary key. How was I supposed to do it properly without loosing the ability to save changes?
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Nov 23, 2011
I have used persistance class and used following LINQ query.[code]but it throws an error saying. "Specified Method is not Supported".How can i get data from two table using XPO Persistance Class?
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Jul 14, 2011
I was toying around with some of the linq samples that come with LINQPad. In the "C# 3.0 in a Nutshell" folder, under Chater 9 - Grouping, there is a sample query called "Grouping by Multiple Keys". It contains the following query:
from n in new[] { "Tom", "Dick", "Harry", "Mary", "Jay" }.AsQueryable()
group n by new
{
[Code].....
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May 6, 2009
Say I create two sets of tuples like so:
Dim losSPResults As List(Of spGetDataResults) = m_dcDataClasses.spGetData.ToList
Dim loTupleKeys = From t In losSPResults Select t.key1, t.key2
[CODE].....................
Now I want to perform set operations on these two lists like so:
Dim loTupleSetDifference = loTupleKeys.Except(loTupleExistingKeys)
Obviously, Linq can't perform a comparator on sets if it doesn't know the sets have uniform definitions, so it will give me this build error:
Option Strict On disallows implicit
conversions from
'System.Collections.Generic.IEnumerable(Of
< anonymous type>)' to
'System.Collections.Generic.IEnumerable(Of
< anonymous type>)'.
How do I work with the declaration of these sets to make them mesh?
Still getting the same compile error:
'*** If we have initialized the list of tools, check to make sure it's up to date Dim loTupleDatabaseTools = From tt In lottTorqueTools _Select StationIndex = tt.station_index, SlotNumber = tt.slot_number
[CODE]...............
Error is here:
Dim loTupleSetDifference = loTupleDatabaseTools.Except(loTupleToolObjects)
Error 5Option Strict On disallows
implicit conversions from
[CODE]........................
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Dec 21, 2010
I have the following in VB:
Dim sources = From source In importSources Select New With _
{.Type = source.Key, .Source = source.Value.Name}
dgridSourceFiles.DataSource = sources
[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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Dec 30, 2011
I'm working on modifying this example:
Using advWorksContext As New AdventureWorksEntities
' Call the constructor that takes a command string and ObjectContext.
Dim productQuery1 As New ObjectQuery(Of Product)("Product", advWorksContext)
[code]....
An ObjectQuery can be enumberated only once. (Subsequent attempts at enumeration throw an exception.) The enumberation takes place in the for each statement. The problem is that if the query is empty attempting a For Each will throw an exception. But if I check for a count:If productQuery1.Count > 0 Then . . .
That eats up my one chance at enumeration. I could nest the For Each in a try/catch block and throw away the empty query exceptions, but that's ugly.
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Jul 14, 2011
given this function:
Public Function Search(ByVal StartIndex As Integer, _
ByVal MaxResults As Integer, _
ByVal AccountNumber As String, _
ByVal LastName As String, _
[Code]....
instead of what I expected:
Select count(*) from remitline where lastname = "smith"
What am I doing wrong building up the where clause? I'm using Castle ActiveRecord 2.1
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Aug 6, 2009
if there is that much of a performance gain in running a LINQ stored procedure versus a LINQ query?
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Apr 20, 2011
I have a listbox on my xaml form that I bound to a List(Of MyType) property. I populated this list like so:
Dim fields As List(Of CheckableFields) = New List(Of CheckableFields)
Using context As ITIPEntities = New ITIPEntities()
Try[code]....
Now I'm at the point where the user selects the fields they want included in a report and I need to iterate over the required fields. This is my linq query:
For Each checkedField In _requiredFields
If checkedField.IsChecked Then
If checkedField.FieldData IsNot Nothing AndAlso checkedField.FieldData.Trim IsNot String.Empty Then[code].....
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Sep 10, 2009
Example-I have a person class
Public Class Person
Private _fname As String
Public Property Fname() As String
[Code]...
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Mar 31, 2011
Forgive my ignorance on this.I have this LINQ Query:Dim ngBikersDataContext As New CarBikeWalkDataContext
bikersList = (From c In ngBikersDataContext.Reg_Bikers _
Order By c.L_Name _
Select New Bikers() With { _
.BikerID = c.BikerID, _
.F_Name = c.F_Name, _
[Code]...
with the error "Overload resolution failed because no accesible 'Select' accepts this number of arguments."
Over the "NEW" I get an error " ')'expected."
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Sep 3, 2009
I found on msdn samples and modified (add Thread.GetDomaind.UnhandledException)
<SecurityPermission(SecurityAction.Demand, Flags:=SecurityPermissionFlag.ControlAppDomain)> _
Public Sub Main()
' Add the event handler for handling UI thread exceptions to the event.[code].....
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Jun 18, 2009
It appears that my favorite thing in the world is tackling projects that are beyond my current knowledge and abilities. I have a little project that I am working on which is a simple image viewer stocked with (upon completion) your standard Load..., Next/Previous, Zoom In/Out, Actual Size, and Full Screen capabilities. However, I am running into a few snags:
(1) I've been able to get my "Load..." button to display a file dialog box, but I cannot seem to get a working filter (with which only image file types are allowed to be selected) in working order.
(2) I have a PictureBox object (entitled PictureBox1) that displays the image selected via the file dialog box, but it loads images in their full size (1:1/100% zoomed) state without scrollbars, etc. to allow me to navigate the loaded image. I would like to have it load the image, initially, to fit within the dimensions of PictureBox1 and from there be able to zoom in/out via my "Zoom In/Out" and "Actual Size" buttons and be able to scroll if the zoom level is beyond the dimensions of PictureBox1.
(3) It dawned on me that I haven't the faintest idea how to get my "Next/Previous" buttons to allow the user (me) to navigate, in succession, the images contained in the folder in which the currently loaded image is stored. [code]
If it is deemed that this thread is inappropriately requesting help, I ask that it be locked/deleted quickly as I recognize that this is a large community with many discussions going without need of unwelcome posts.
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Jan 27, 2011
We are doing a query against an in-memory collection of LINQ data objects. The wrinkle is that we are ordering by a column in a related table whose records have not necessarily been loaded yet (deferred loading:)
Dim oPkgProducts = _
From b In oBillPkg.BillProducts _
Where b.Successful.GetValueOrDefault(Common.X_INDETERMINATE) = _
[code]....
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Feb 28, 2012
The pattern I'm trying to avoid is checking if a string (normally a control's text value) is null/empty, and if it is, comparing it using Contains to a field in my data. Obviously the field isn't hard-coded into my extension, neither is the object type.What I've got works perfectly in Linq to Objects, but I get the generic run-time error "LINQ to Entities does not recognize the method 'System.String Invoke(GenericQueryHelper.Customer)' method, and this method cannot be translated into a store expression." when using an entity framework model.
Here's what I have:
<System.Runtime.CompilerServices.Extension()>
Public Function CompareAndFilter(Of T)(source As System.Linq.IQueryable(Of T), expressionField As System.Linq.Expressions.Expression(Of System.Func(Of T, String)), compareTo As String)
[code]....
I want my usage to look something like this:
Dim results = repository.Customers.CompareAndFilter(Function(c) c.FirstName, searchText)
I do need to get this running against a SQL database really, as it is filtering results, so I don't want to be doing that in memory.
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Jun 27, 2012
How can I convert this code LINQ to SQL in C # LINQ to SQL in Vb.net
[Code]...
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Aug 31, 2011
How do I add ROW_NUMBER to a LINQ query or Entity? How can I convert this solution to VB.NET?
[Code]...
I'm having trouble porting that last line. I have been unable to locate a VB.NET example. I'm actually not looking for any paging functionality like the example provides, just good old-fashioned Row_Number(Order By X) row index.
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Oct 21, 2009
How can I convert an object of type System.Data.Linq.DataQuery to System.Linq.IQueryable?I'm working with Visual Basic/Silverlight, and the source code of my query is as follows:
Public Function Get_Cli_Pag() As IQueryable(Of V_Cliente_Pagare)
Dim Qry = From P In Me.Context.Pagares Join C In Me.Context.Codigos On C.Codigo
[code]....
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Sep 22, 2009
I know that LINQ queries are deferred and only executed when the query is enumerated, but I'm having trouble figuring out exactly when that happens.Certainly in a For Each loop, the query would be enumerated.What's the rule of thumb to follow? I don't want to accidentally enumerate over my query twice if it's a huge result.
For example, does System.Linq.Enumerable.First enumerate over the whole query? I ask for performance reasons. I want to pass a LINQ result set to an ASP.NET MVC view, and I also want to pass the First element separately. Enumerating over the results twice would be painful.It would be great to turn on some kind of flag that alerts me each time a LINQ query is enumerated. That way I could catch scenarios when I accidentally enumerate twice.
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Feb 22, 2012
I recently switched from VB to C# and have, for the most part, been able to make the transition without too much trouble. Currently I am working on converting a VB.Net program into C# and am having trouble with a couple of code blocks that include Linq.
This is one of the VB.Net lines of code that I am having trouble with:
I have tried to do the same thing in C# like this:
I am getting a compile error on the dt, which says Could not find an implementation of the query pattern for source type 'System.Data.DataTable'.'GroupBy' not found. VS also has issues with the whole into Emailers = group;
I have tried to get this right using examples from my search but have not been able to get it right.
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Jan 19, 2012
I'm using loop to read data from sql and then make some calculations then save it again to another table but when application loop for 3 or 4 times it's freeze but the job is done but if loop = 10 or more then it is freeze and hangup for long time .i need to learn how to make my application working better and never freeze and make application working with any count for loop without freeze .
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