Deserialize An Object When The Underlying Class Has Been Changed Slightly?
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]....
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Aug 3, 2011
I am retrieving data from my database using a TableAdapter. I was wondering if there is some way I can tell (or be informed) that the data has changed and I therefore need to do another Fill? That way I can just Fill on demand rather than every time the user requests to see the information and I am forced to do a Fill before showing the data because I don't know if is current or not. For the record I am using an ODBC connection string to access a Pervasive PSQL database
EDIT I was thinking I could check the last write time of the MKD file to check if this has changed but this doesn't seem to be reliable as it is not written to until the connection is closed. Does anyone know the circumstances when this is written?
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Jan 5, 2010
I have a program that opens a FormReportViewer. I get an error when I close my program...COM object that has been separated from its underlying RCW cannot be used.
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Dec 13, 2011
I'm designing an ATM where I have to allow a user to "insert" his card and then conduct transactions. After the first user is done, without closing the application, another user should be able to use the ATM. However, whenever I try to log the second user in, I get the following error: COM object that has been separated from its underlying RCW cannot be used.
My code for the opening screen is as follows:
Imports System.Data.OleDb
Public Class StartScreen
'Form-wide variables
[code]....
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Jun 29, 2012
Ok, so I'm playing with some FTP profile files that are written in XML. I'm trying to get the program to be able to read the current users settings and fill in or remove servers they do or don't have access to. So the XML looks like
<?xml version="1.0" encoding="UTF-8" standalone="yes" ?>
<ftp>
<servers>
[code].....
it's probably more cosmetic than anything but the logic just doesn't flow to look over 'server' and not 'servers'?!
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Sep 13, 2011
I'm having an issue with getting some of the values from with this json string:
{
"kind": "shopping#products",
"etag": ""YZWJaKE3MHROIW8rCIlu9mAACLM/6qxBB-GwuSPy5L3_zVS6sS2NYFI"",
"id": "tag:google.com,2010:shopping/products",
"selfLink": "https://www.googleapis.com/shopping/search/v1/public/products?country=US&
[code]....
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Feb 23, 2010
We are trying to consume WCF service which returns employee details in JSON Format.like:
{"d":[{"_type":"Employee:#","BigThumbNailURI":null,"ID":1,"Name":"E1"},{"_type":"Employee:#","BigThumbNailURI":null,"ID":2,"Name":"E1"}]}
From VB.net code behind when I am trying to deserialize it it's stating that "Expecting state 'Element'.. Encountered 'Text' with name '', namespace ''."
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Oct 29, 2010
How do you deserialized a serialized object?I'm trying to extract the serials of fingerprint template which will be stored to the database. Here is my
Dim features As DPFP.FeatureSet = ExtractFeatures(Sample, DPFP.Processing.DataPurpose.Enrollment) <--- Serialized Object
And here is my sad failure attemp:
SetText(String.Format("Stat: {0}", features.DeSerialize(WHAT SHOULD I PUT IN HERE????)))
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Feb 3, 2012
I was searching the most effective and elegant way do to the follows:
My function can be called while Filename is valid, corrupted, not exist
The function will just deserialize an XML object.
The main possible results are:
OK
File doesn't exist
Error in XML file
If I write this way, the reader won't be closed in case of corrupted file. IF I write the reader.close() inside finally block, It gaves me a warning about using read before assigning it a value.
So, how can I solve this inside the sub?
Public Function DeSerializzaXML(ByVal FileName As String, ByRef tmpObj As Object, ByVal tmpClass As Type) As Boolean
Dim serializer As XmlSerializer
Dim reader As StreamReader
[CODE]...
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Mar 24, 2011
In VB.Net class, I have a JSON data as string. I want to convert them to LINQ class Object.[code]....
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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.
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Jun 1, 2010
I have got a code snippet as follows:
Dim fstream = new filestream(some file here)
dim bwriter = new binarywriter(fstream)
while not end of file
read from source file
bwriter.write()
bwriter.flush()
end while
The question I have is the following. When I call bwriter.flush() does it also flush the fstream object? Or should I have to explicitly call fstream.flush() such as given in the following example:
[Code]...
A few people suggested that I need to call fstream.flush() explicitly to make sure that the data is written to the disk (or the device). However, my testing shows that the data is written to the disk as soon as I call flush() method on the bwriter object.
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Jun 7, 2010
I am utilizing a centralized class object that needs to call another class object. The program itself will do something like the following
sFieldValue = CentralObject.ObjectHandler(1, TestFunction, "FunctionVar,FunctionVar2,FunctionVar3")
In the central object I have a function
Public
Function ObjectHandler(ByVal ObjectType
As
Integer,
[code]....
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Jul 10, 2010
I am somewhat new to object oriented programming and am attempting to flatten a Linq object hierarchy by using a shim class.how to initalize a derived class with property values from a base class?I have two objects, a base object with about 100 properties, and a derived object which inherits from the base object and adds a few additional properties beyond those of the base object. My simple constructor creates the derived object, but I am looking for a way to initialize the derived object properties with values from the base object.Right now I am using reflection to iterate over the properties individually and I suspect there may be a better way. The following example shows my shim class constructor for the derived class, and two properties:
newProperty1 - a new string property of the derived class
flattenedProperty2 - a new string property of the derived class, copied from a 2nd-level object of the base class
Code example:
Public Class derivedObj
Inherits baseObj
Private _newProperty1 As String[code].......
Is this the correct constructor approach to flatten the object hierarchy using a shim class? My second question relates to initialization of properties in the derived class. The constructor above creates the derived object, but what is the best way to initialize the derived object properties with values from the base object? The following code uses reflection to iterate over the properties individually, but I suspect there may be a better way.
Code example:
' property names are in the string array fieldNames
'baseObjQuery is an ienumerable of baseObj
'derivedObjList is a list of derivedObj[code].....
Is there a simple way to initialize values for the properties in the derived object based upon the values of the common properties in the base object?
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Feb 23, 2009
In VB6, if I have an existing program that only needs to be slightly modified,I copy it by Doing file Save Form as...And file Save Project as...How can the same result be acheived in VB.net?
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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.
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Jan 24, 2010
creating a business layer in a .dll which at the moment is being used on a windows forms application. I have some objects with properties that use iNotifyPropertyChanged to update the UI which has all been working fine. My problem is tarted to explore using multiple threads and ing a cross-thread error because the properties are being changed on a different thread to the UI and iNotifyPropertyChanged is attempting to update the values (shown in labels) on the UI thread... shows the best way to solve my problem. The .dll will never know what Forms application is using it so I really dt want to hard code references into the objects. From what I gather this code allows you to register a form with the .dll and then add the invoke to OnPropertyChanged to avoid any threading issues. Is this correct?
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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?
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Nov 14, 2010
I am using a class to track if a user cleared their personal information found within some text boxes on a form. In the button click event to clear the text boxes I am creating a new object to the class and assigning true to one property value. Sounds simple until I try and submit the form with a different button, and create a another object reference that I use in an IF statement to check the property value for true. Every time the statement fails because the value being returned from the getter in my class is false.
[Code]...
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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?
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Aug 6, 2010
Here is the structure that I have:
Friend Class StandardFormatFile
Friend fileType As String
Friend numberOfSeries As Integer
[code].....
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Aug 18, 2009
I have some classes, BsfciFile and StudyFlashCard. Bsfci is the extension to which I save my set of flashcards in an INI format. I am currently working to transform my code from using Windows API calls to access the INI to using a IniFile class that I found on the internet. I would like the BsfciFile to have a Array of StudyFlashCard objects, but I would like the StudyFlashCard class to use the IniFile class object contained in the BsfciFile class. I can pass the IniFile from the BsfciFile class to the constructor for the StudyFlashCard class, but I want it to modify the same IniFile as the BsfciFile class has later on.
[Code]...
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Jun 21, 2010
I am trying to create an list or an array of a class.Here is my "Ingredient" class that I am trying to create a list of:[code]In my "recipe" class, I am want to create a list (or array) and I am drawing a big blank on how to do it. Can anyone point me in the right direction?
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Aug 11, 2009
dim myCollection as new Specialized.StringCollection
dim myFoundThings as new ArrayList
dim index as Integer
dim newResultMemberName as String
[code]....
This is part of some code that will run without user interaction once it's spinning away, and I need to create a unique object from some items found in a StringCollection, naming the objects using information found in the strings stored in that StringCollection.
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Dec 15, 2011
I'd like to have something like:
[Code]...
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Jun 15, 2009
i've created bunch of classes. i have webservices which reference these classes and contains the classes as parameters and return objects.when i call the weservice, i have to convert the class to the webservice object else i can type conversion error.is there a generic way to convert between these types without having to assign the values by hand?
for example
public class person
fname as string
lname as string
end class
[code]....
i would liek ot be able to call the web service and return the data type back and have a generic coversion instead of as above in stead of:
dim wsPerson as wsReference.Person = ws.getperson()
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Aug 19, 2009
I have a class in which some of the fields are also classes.
I can put values in the "normal" properties, but in the others when o try to assign values it gives the: "Object reference not set to an instance of an object"
But the code compiles fine.
dados_Defenicao = New ServiceReference1.draftClaimEntryDefinition
dados_Defenicao.arCode = "123"
dados_Defenicao.claimMarket.warrantyType = "w" - Here it gives the error
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Dec 10, 2010
If we are within the derived class then ofcource we can use MyBase keyword to access base class's object reference . That's fine , how can we take that base class's object reference outside that derived class's definition.My following code will explain what i want . Actually that is giving error right now, but it is explaining my requirement .
Public Class Base
Public x As String
End Class
[code]....
Actually there is error in ReadOnly Property BaseReference's Getter . Error is "Error 1 'MyBase' must be followed by '.' and an identifier. " how can i get base class object reference in Main method ?
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May 22, 2009
If my namespace is Company.Application.EDI.Acknowledgement and if I stick with theprogramming practice of one class per file then should my class be saved asacknowledgement.vb? Are there any gotchas that will come up?
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Jan 2, 2010
I have a Parent Class Called Fuselage that containsfour child classes called Forebody, CenterBody, AftBody, and CrossSection. CrossSection classcontains objects common to Forebody, CenterBody, and Aftbody (example: width). How do I access thewidth property in CrossSection from within the classForebody?
Public Class Fuselage
Dim Forebody As ClsSection
Dim Centerbody As ClsSection
[code].....
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