.net - LINQ To SQL A Member Defining The Identity Of The Object Cannot Be Changed?
Nov 29, 2009
I'm writing a Generic for LINQ to SQL CUD. I
'Generic Insert
Public Shared Sub Add(Of T As Class)(ByVal entity As T)
Using db As New APIUDataContext()
[code]....
Error message from Generic Update.Value of member 'Id' of an object of type 'TestAuthor' changed.A member defining the identity of the object cannot be changed.Consider adding a new object with new identity and deleting the existing one instead.What do I need to modify the Generic Update?
View 2 Replies
ADVERTISEMENT
Jan 3, 2011
I get this error if I follow these steps: Change property Y of an object (an associated entity property)
Attempt to submit changes At this point the value of Y and the value of X (the underlying key) are not in agreement -- LINQ to SQL apparently doesn't synchronize these until GetChangeSet is called.An expected error occurs due to some business logic or database level constraint during the update operation.At this point the value of Y is in agreement with X because GetChangeSet was called.Change the value of Y to Nothing (aka null).Call GetChangeSet.
The error occurs on the last step because the value of X and the original value of X (returned by GetOriginalEntityState) are different, and the new value does not agree with Y? Is that why? Is this a bug in LINQ to SQL. Must be because I don't see the same behavior if I change Y to another (non-null) value instead during step 5. What's the right way around this? I can see a few ways:
Discard the DataContext when an error occurs and leave the UI as-is. I don't like this because then optimistic cocurrency change conflicts cannot be detected. The new context doesn't have the original values in it that were populated at the same time the UI was populated, so if the UI has any stale values in it, they will cause data in the database to revert.Refresh the datacontext (OverwriteCurrent) and leave the UI as-is. I don't like this for the same reason as #1.Refresh the datacontext (OverwriteCurrent) and re-populate the UI. I don't like this because then the error message just presented to the user does not show the user the error they made and allow them to correct it. It also discards all the other changes the user may have made.When the error occurs, explicitly retrieve the key for Y that corresponds to the original value of X and reset Y, then call GetChangeSet to re-synchronize X (X is read-only or private so I can't reset it directly). This seems to work, but seems like a hack, and may require lots of code for other similar errors.
View 2 Replies
Jan 27, 2010
I am tightening up my coding with the Option Strict set to ON. It has now produced alot of errors. An example of this is:
If AllocatedDGV.Rows(i).Cells("RoomNumber").Value = RoomsAvailableDGV.Rows(j).Cells("RoomName").Value Then
It gives me the following error: Option Strict On disallows operands of type Object for operator '='. Use the 'Is' operator to test for object identity.
View 6 Replies
Apr 6, 2012
I need to write an interface to get data to/from our data files.
We have a low level class that holds field values for each record read from the files.
This just holds two values, the value read from the file (DBValue) and the updated value that may need to be written back to the file (CurrentValue).
These values may be any of the standard value types (integer, date etc) or a string.
Either value (DBValue or CurrentValue) may be null if not defined.
I have written the class to manage this data which works fine while option strict is NOT on.
But we have an office policy of having option strict on all the time.
When I put option strict on, my object value comparisons fail with the error: "Option Strict On disallows operands of type Object for operator '='. Use the 'Is' operator to test for object identity."
Question, how should I change the following code to handle option strict on ...
This is all running on Visual Studio 2010
[Code]...
View 1 Replies
Feb 27, 2009
Private Sub cbxSubject_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cbxSubject.SelectedIndexChanged
Select Case cbxCategory.SelectedItem
[code]....
I get this error message:Option Strict On disallow operands of type Object for operator '='. Use the 'Is' operator to test for object identity.But I don't know how to correct this.
View 3 Replies
Jun 7, 2012
I know how to handle a single objects property changed event very easily. I want to handle a objects property changed event that is part of another object.
Given Object:
[ObjectY = Y]
+ Public WithEvents X As ObjectX
I would like to do something like:
Private Sub XPropertyChanged() Handles Y.X.PropertyChanged
Right now I need to create a object that equals the object inside that object and then handle this variable pointers property changed, but that is just annoying.
View 1 Replies
Aug 6, 2010
Here is the structure that I have:
Friend Class StandardFormatFile
Friend fileType As String
Friend numberOfSeries As Integer
[code].....
View 3 Replies
Jun 2, 2011
how do I overcome it? I have created a class and compiled into .dll This code
[Code]...
View 2 Replies
Aug 13, 2009
In Visual Studio 2008, if I do this:
[Code]....
Does anyone here know how to get the above to work WITHOUT warnings being generated?
View 4 Replies
May 31, 2010
In the following code i get a warning at line 59:Warning 1: Access of shared member, constant member, enum member or nested type through an instance; qualifying expression will not be evaluated.and.. At line 78 I get this Warning:
Warning 2 Property 'SelectedCustomer' doesn't return a value on all code paths. A null reference exception could occur at run time when the result is used.
The program compiles and runs well, but i cant' undesrtand the reason for these warnings. Any Idea ?
1: Public Class Form1
2:
3: 'Form level members
4: Private objCustomers As New ArrayList
[code]....
View 5 Replies
Aug 24, 2010
I have a class:
[Code]...
Now I can change the TextBoxes or the object: MyObject.Two = 3 ..the object and TextBoxes are updated in two ways. Now I want to update the whole object: MyObject = New TestClass(3, 4) ...but this doesn't update the TextBoxes.
View 1 Replies
Apr 28, 2011
Cannot appear to be able to get this function to not have the above error.Private Function GetIncidentActions(ByVal FromAgentID As Integer, ByVal ToAgentID As Integer, ByVal incidentAction As Integer, ByVal ActionDate As Date) As String
[Code]...
View 10 Replies
Feb 10, 2010
This starts with an object being added to a collection with: CommonArgs.Add(ObjName, Me)
ObjName is a string, call it "Obj1". Me is an instance of a class inheriting from UserControl. Call it "Class1".
Now, to check the value assigned to Obj1, the vendor has the
Dim Obj As Object = CommonArgs(ObjName)
Dim Info As System.Reflection.FieldInfo = Obj.GetType().GetField(ObjName, System.Reflection.BindingFlags.Public Or System.Reflection.BindingFlags.Instance Or System.Reflection.BindingFlags.IgnoreCase)
Obj is the Class1 object added to CommonArgs.
When I run this in my test app, Info is Nothing-but when I run it in the vendor's app Info is an Enumerated type. Why?
I've found a little more info, but it's still a mystery to me-and so far it appears to be a mystery to everybody else, too.
First, I noticed that I didn't mention that the Collection is a Hashtable. I don't know if that would make a difference, but it is something I forgot to mention.
Second, there's a 'regular' variable named ObjName that contains the value being returned by Info. My understanding is that there's no connection between these, e.g. Dim X as Integer = 1 doesn't change the type or value of the object of CommonArgs("X"). But that's what appears to be happening.
Any suggestion?
View 3 Replies
May 10, 2011
I've written a custom class MyClass and marked it with the <Serializable()> attribute. I have a set of binary files on my hard drive that I've serialized using BinaryFormatter that came from instances of MyClass.
I've recently changed the structure of MyClass slightly (added some properties, deleted some properties, changed a few methods, etc).
What happens when I try to deserialize the existing objects to this changed class using the code below? I've tried it and not had an error thrown or anything - but surely it can't deserialize properly when the class has changed? Is there a way I can get some useful information out of the serialized files even though I've updated the class?
Here's the code I'm using to do the serialization:
Public Sub serializeObject(ByVal obj As Object, ByVal outFilename As String)
Dim fStream As FileStream
Try
[Code]....
View 4 Replies
May 14, 2011
I'm building a litle console app that involves a control hierarchy -- there are screens, and inside of screens you can compose controls together.
You can add controls to a screen by declaring member variables (which all inherit from AresControl). The control constructor takes a simple coordinate pair. It looks like this:
Public Class IntroScreen : Inherits AresScreen
'Controls
Private LabelSelect As New LabelControl(72, 0)
[Code]....
This would result in cleaner, convention-based code. But try as I might, I can't get it to work - I can walk the member variables of a type, but I need to walk the member variables of a live object.
View 2 Replies
Jul 29, 2011
I am getting following error whenever I want to use IIf function inside entity framework query.
LINQ to Entities does not recognize the method 'System.Object IIf(Boolean, System.Object, System.Object)' method, and this method cannot be translated into a store expression.
View 1 Replies
May 29, 2010
I have a routine that accepts a List of Objects, a property name and a value to search for and simply returns whether or not it found it.The code I have hangs up at the For loop in the findit routine.[code]
View 4 Replies
Apr 29, 2009
I was trying to make a reference with a constant but of course I can't do that and before hand I get this error "Refrence to a nonshare member requires an object references" But umm I know I need to make an instance but I really am confused how for the construct. Here is my code: THis is just the class
Public
Class Information
Private CarsDecimal
As
[Code]....
View 3 Replies
Nov 16, 2011
I have a combo box that is populated with a list of objects (corresponding to all employee rows from a database that meet the criteria IsTech). These are not entity objects though, I have created my own class that stores the member values of each row from the DB. I have set the DisplayMemberPath to EmployeeId so the Combo box display the EmployeeId ( an integer ) member of my object. Ie. right now there are only 2 IsTech employees in my DB so the combobox displays the numbers 3 and 8 ( their EmployeeIDs).
[Code]...
View 3 Replies
Jun 22, 2009
I'm not sure if I'm going mad, it's always a possibility. But is it possible to call a shared member of a class given its 'System.Type' object?
View 4 Replies
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]....
View 1 Replies
Jun 12, 2010
I have created a class called 'MyAddress' and in the form load event i am adding few objects of that class to the combobox. I want to know how should i set and read the values of the member variables of that selected item of the combobox. I have tried this and is working, but i am not sure whether it is the way to do
vb
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
[code].....
View 2 Replies
Mar 24, 2010
The following code returns the error from the For Each loop. I have similar code that does not return the error.
'DisplayTitle' is not a member of 'Sting'[code]...
View 1 Replies
Jan 12, 2012
I have got this error No default member found for type 'VB$AnonymousDelegate_0(Of SqlDataReader,String,Object)'.
My Code is below
dsBranch.Tables.Add(GetDataTableFromSQLReader(dr, "")) - Calling
Private Function GetDataTableFromSQLDataReader(ByVal dr As SqlDataReader, ByVal TableName As String)
[code]....
View 1 Replies
May 5, 2012
I changed my Username on my computer from i.e. "xxxxxx x xxxxx" to "Dennis"
VB 2008 during a compile gave me the following error: Error reading icon 'C:Usersxxxxxx x xxxxxAppDataRoamingMicrosoftVBExpress9.0VSProjectApplication.ico' -- The system cannot find the path specified.
The file "VSProjectApplication.ico" is in 'C:UsersDennisAppDataRoamingMicrosoftVBExpress9.0'
Somewhere in the VB2008 "configuration" files I believe that I need to manually change the old path to the new path.
I found the old path in the ".suo" file. The ".suo" file is not a text file. How can I edit the .suo file, save it so that it will work?
View 4 Replies
Jan 20, 2010
on my Form I have a DataViewGrid and some textboxes with a save button (they are filled with additional data of the selected row).Save is disabled first, when I change something in the textboxes the save button is enabled.When the user changes a gow in the grid, I want to ask before changing the grid row, if he wants to save (if the button is enabled).I am using RowEnter but this is too late, then the selected row already changed (and my textboxes already got new data)...What event can I use to ask if I should save stuff before the user changes a row?Something like BeforeRowChanging with a chance to cancel changing the row?
View 2 Replies
Jan 27, 2012
I have the following line of Dim clients = From client In db.clients Select client Where client.ClientID = id
In debugging, the clients object populates perfectly, but how can get get data from the clients object? Like if the clients object has a FirstName property, how can I set a textboxes text property to that property from the clients object?
I thought it'd be something like:
tbClientFirstName.Text = clients.FirstName But that doesn't work.
View 2 Replies
Mar 1, 2010
how to convert a linq query directly back to the same object type. But I have failed!
Dim test(2) As myStructures.ReturnData
test(0).Partnumber = "2055"
Dim result = From n In test _
Where n.Partnumber = "2055"
'now convert result to a myStrucutres.ReturnData() how?
View 3 Replies
Nov 18, 2009
I'm "cloning" objects in my code. For instance: objClone = objOriginal My question is: Does the assignment operator in VB.NET 1.1 do a member-by-member copy of the objOriginal to objClone or does objClone simply point as a reference to memory referenced by objOriginal?
View 3 Replies
Nov 28, 2010
I am receiving this error: Reference to a non-shared member requires an object reference on the code I've
bolded within the code body. Here is my code:
[Code]...
View 1 Replies
