Asp.net - Copy Object Types ?
Jul 29, 2010
I am building an ASP.NET application that needs dynamic tables. That's another issue that I've already posted about (and gotten a pretty good response!). Now, I'm running into another issue - I want to add new rows to my table, but given that I will have 10-12 tables on one page, each containing different objects in their rows (text boxes, check boxes, etc.) I need a way of simply generically adding a new row that has the same objects as the first row in the table. Here's my code:
Private Sub AddTableRow(ByRef originalTable As System.Web.UI.WebControls.Table)
Dim originalRow As System.Web.UI.WebControls.TableRow = originalTable.Rows(1)
Dim insertingRow As New System.Web.UI.WebControls.TableRow[code]......
Stepping through with a debugger, I see that this strategy is working - but the additional table row still doesn't appear...and still does when I do this statically.
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Nov 1, 2009
I have a class with a Property called 'Value' which is of type Object.Value can be of any type, a structure, a class, an array, IList etc.My problem is with the setter and determining whether the value has changed or not.This is simple enough for value types, but reference types and lists present a problem.For a class, would you assume that the Equals method has been implemented correctly, or just assume that the value has changed every time the setter is called?If I did assume it's changed, then perhaps I should assume it for value types as well, so that the behaviour is consistent.
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Mar 29, 2010
I am having some trouble creating an object array of different object types. Here is what I have so far:
Public Sub New()
Dim b1 As New Book("Book Title 1", "Gold Book Publisher", 1.0, "Bob Jones", "192DJDJD212", "01/02/10")
Dim b2 As New Book("Book Title 2", "Gold Book Publisher", 1.0, "Bob Jones", "192DJDJD212", "01/02/10")
Dim b3 As New Book("Book Title 3", "Gold Book Publisher", 1.0, "Bob Jones", "192DJDJD212", "01/02/10")
[code]....
If I define the array As Book (Public publicationArray(6) As Book) or Magazine (Public publicationArray(6) As Magazine) I am able to access the properties of that class but not both. I think I need to define a type for each array instance but not sure how to do this.
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Sep 27, 2010
I understand that different data types have different uses, String for text, Integer for numerical ect. However, if the Object type can be used for ALL types and supportive of everthign then why should i worry about using correct data types such as string and integer if i can just use "Object" for them all and it will work.I could do
Dim Test as Object = "John"
or i could do
Dim Test as String = "John"
They both do the same thing; there must be something very important im missing here but can only think of one thing that it could be; Memory Management.I think that by using a type such as object may take up more memory than using string?
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Feb 1, 2012
In VB.net, when I retrieve a value from a list do I get a copy of that value or a reference to it?
dim blah as someObject
dim listOfBlahs as list(of someObject)
listOfBlah.add(new someObject(1))
[Code]....
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Feb 3, 2011
Here's what I'm looking to do. I have an array of objects that all implement a particular interface. What I want to do is search that array of objects for a particular object type.I have to do this in several places, so I'm trying to create a function where I pass in the object array and the type that I'm searching for, and have that function return the object that matches that type - or nothing if no match is found.I wrote the following, but it isn't working, so I'm missing something:
[code]...
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Apr 15, 2011
I'm trying to figure out how find an object's type when it is a subclass of another object and I only know the string value of the object's type's name.I created the follwing classes:
HTML
Public Class word
End Class
Public Class noun[code]....
The problem is, using 'GetType' to check pn against a string value, I can only see that pn is a properNoun, not that its parent classes are noun and word.Is there a way to check pn against the string value "noun" or "word" and get back a positive result, indicating that pn is indeed a noun and a word as well as a properNoun?
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Feb 10, 2010
My quest is in regards to xml serialization. I need to get rid of the root node of a collection. I don't have access to my source now so I'll just try to generalize
public class SomeClass
'...some other properties...
<XMLArray(isnullable:=true), _
<XMLArrayitem(datatype:=(getType(object1)), _
[code]....
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Nov 9, 2011
I am having problems with my code, where I get the "Object cannot be cast from DBNull to other types" message when Insert(). I get the message on every Insert to this table, even though the data is successfully inserted. If I Update the same data after Insert(), it does so without error. I have checked my values and none of them are DBNull. Even when the same values are passed on Insert that are passed on Update.
My code is :
Private Sub Save()
Dim bo As tbl_GL
bo = New tbl_GL()
bo.ConnectionString = AppConfig.ConnectString
[Code] .....
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Feb 15, 2011
Given a list of objects, I'd like to print a string version of them just in case the object.ToString() result is a relevant string.By that I mean I don't want to get things like:
obj.ToString() -> System.Collections.Generic.List`1[MyLib.Dude]
obj.ToString() -> System.Collections.Generic.Dictionary`2[System.Int32,System.DateTime]
obj.ToString() -> System.Byte[]
But I want to get things like:
obj.ToString() -> Hi
obj.ToString() -> 129847.123
obj.ToString() -> Id = 123
What should be the best way to implement this in a method:
Public Sub PrintInterestingStuffOnly(ByVal coolList as Ilist(Of Object))
For Each obj in coolList
'insert solution here
[code].....
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Jan 1, 2008
I have set my datasource on my datagridview to be a subset of rows as follows:
dg.DataSource = myDataSet.testTable.Select("id=" & id)
But I get a runtime error that Operator '=' is not defined for types 'Object' and '1-dimensional array of DataRow' There should be an easy way to do this that doesn't involve creating new tables, etc.
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Feb 4, 2011
.net 3.5, VS 2010... this is for an asp.net website.I have an class called Agency. there is a second class called Agency_Queries. Agency_Queries inhertis the Agency class. I'm trying to create a function that will copy the like properties in Agency to Agency_Queries. I figured out how to do that.. but when i try to make it more generic so that i can pass in my class name and lists i'm doing something wrong.So if there is an list(of Agency) that needs to be copied to list(of Agency_Queries) i've got something like the following.
Dim AgencyS As List(Of Agency) = Nothing
Dim Oc As New Agency_Controller
AgencyS = Oc.GetAgencyData(0)
[code]....
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May 23, 2010
I have an class called Agency. there is a second class called Agency_Queries.Agency_Queries inhertis the Agency class. I'm trying to create a function that will copy the like properties in Agency to Agency_Queries. I figured out how to do that.. but when i try to make it more generic so that i can pass in my class name and lists i'm doing something wrong.
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Jul 10, 2004
How can I copy an object? When I use obj1 = oby2 I copy only the pointer. I know some objects have the methode .clone. But What's about the other ones? Some objects (for example a button) I can copy of course by creating a new object and set each property. (btn1.Left = btn2.Left) But that works rarly. And of course what's about my own classes? Is there now change to copy them like you can do it for example in C++...?
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Feb 27, 2009
I am trying to copy the contents of one graphics object to another, but the only was I have been able to find is based on using GDI32.DLL, which i would rather avoid using if possible.Does anyone know how/if this is possible using managed code? I don't mind if answers are in C# or VB.Net.
[Code]...
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May 12, 2012
I have a form which has a ListView and buttons to add/edit/delete items from this list. It has a save & a cancel button. On pressing the cancel button, I want to revert all the changes that have been done in the current form. So, while loading the form I keep a copy of the original list like below.
backupMyListView = MyListView
In the cancel button code, I do the opposite.
MyListView = refMyListView
Whats happening is that, the original listview is never restored because everytime MyListView was updated, backupMyListView also was getting updated.
How do I restore the original ListView on pressing the cancel button?
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Mar 27, 2009
i have a user define object which i'm initializing with data from external datafiles.... the purpose of this object is to reduce the amount of disk/data access and processing required every time i need to add an instance of this object to a collection.so, whenever i add a copy of this object to a collection, i would simply reference the "base" object, and avoid having to process all the data and perform the conversion and so on...the issue is when i add the object
Collection.add(Base_Object, Key)
the collection ITEM is a Reference to the base object and not a copy.
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Jan 8, 2009
Is there any method or a way to copy a form object to a variable? Let me explain this - We have a method called "Copy" for the Dataset class & you all must be knowing that there is a difference between the below two lines of code: DsTemp = Ds DsTemp = Ds.Copy()
In the first line of code, any changes made to Ds will reflect in DsTemp. However, in the second line of code, any changes made to Ds will not reflect in DsTemp because we are only "copying" the contents & schema of Ds. Likewise is there a method or a work around to "copy" a Form object?
[Code]...
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Jul 29, 2010
Rather than giving the very specific case (which I did earlier), let me give a general example. Let's say that I have a function, called callingFunction. It has one parameter, called parameter. Parameter is of an unknown type. Let us then say that I wish to copy this parameter, and return it as a new object. For example, in pseudo code, something along the lines of...
[Code]...
EDIT: Additional Information The first time I posted this question, I received only one response - I felt that perhaps I made the question too specific. I guess I will explain more, I have an ASP page with 10 tables on it. I am trying, using the VB code behind, to come up with a single solution to add new rows to any table. When the user clicks a button, a generic "add row" function should be called.
The difficulty lies in the fact that I have no guarantee of the contents of any table. A new row will have the same contents as the row above it, but given that there are 10 tables, 1 row could contain any number of objects - text boxes, check boxes, etc. So I want to create a generic object, make it of the same type as the row above it, then add it to a new cell, then to a new row, then to the table.
[Code]...
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Jan 26, 2010
I have a Class called People.I have an object called Roger, another called Sally.How can I copy my 'Roger' object over top of 'Sally' so they are identical?
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Sep 3, 2006
is there a way to copy selected text out of a WebBrowser object? I tried:
Webbrowser.Select()
Clipboard.SetDataObject(Webbrowser)
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Mar 12, 2010
I would like to make a "deep copy" of a class object that I have defined. See Visual Basic 2005 Code below
Dim MyStuff1 as new MyClass
Dim MyStuff2 as new MyClass
mystuff1.getbyID(anID)
mystuff2 = mystuff1
Unfortunately the statement "mystuff2 = mystuff1" makes a "shallow copy" of mystuff1. Therefore, if mystuff1 is redefined then so is mystuff2. What do I have to do in MyClass to implement a deep copy method such that operations on mystuff1 and mystuff2 are independent?I would prefer something like
mystuff1.deepcopy(mystuff2)
or
mystuff2 = mystuff1.deepcopy()
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Dec 14, 2011
I have a generic Class I'm using to hold information loaded from a database.I have a method which takes a DataRow as an argument, uses the object's known column name and extracts the data from the DataRow, such that:Dim loadData As T = CType(myDataRow("myColumnName"), T))works as my default assignment in most cases.Unfortunately, due to some horrifying design constraints, some of my columns may be null, and may also be taken from enumerations.This means that when <T> is Nullable(Of SomeEnumeration) the above code does not work because I can't cast 0 directly to SomeEnumeration.Zero.Is there some way to check whether <T> is Nullable(Of [Enum])? Or some way to write a method which allows Integers to be cast to Nullable(Of [Enum])?I feel like I'm forgetting something that would allow me to write one of the other of these, but my weak google-fu is turning up nothing.
EDIT: Okay, thanks to dasblinkenlight's answer below, I can detect when this circumstance is occurring, but what I need to do now is to take a type <T> which I know is Nullable(Of SomeClass), get a type reference to SomeClass and then create a new object of type Nullable(Of SomeClass) and assign that to LoadData.My problem was that I had a lot of difficulty in finding any function which would accept baseType as an actual Type.Parse accepted baseType as a parameter, I knew baseType was an [Enum] type because of dasblinkenlight's code, so I was, in this instance, able to code a solution. It's a solution which is very specific to my problem (i.e., T is Nullable(of SomeEnumeration)), but it's a solution nonetheless.
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May 1, 2009
how can I troubleshoot "Object cannot be cast from DBNull to other types."?I am using a combobox, to retrieve the price and discount price of the service, If I select an item in combobox3 once, error will not occur, but if I select a item again in combobox3, "Object cannot be cast from DBNull to other types." will occur..here is my code
Private Sub ComboBox3_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ComboBox3.SelectedIndexChanged
Dim ds As New DataSet
[code]....
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Aug 5, 2011
If I instantiate an object within a function in VB.NET and return it, does it return it be reference or by value. IE - should I be worried about performance if I write something like this:
Public Function ret_obj_func() As big_object
Dim ret_obj As New big_obj(<lots of stuff>)
Return ret_obj
End Function
If I call this function from somewhere else, will it instantiate the object in the ret_obj and then create a deep copy to pass back a copy to the caller, Or will it just pass back a reference?
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Jun 20, 2012
how can I troubleshoot "Object cannot be cast from DBNull to other types."?I am using a combobox, to retrieve the price and discount price of the service, If I select an item in combobox3 once, error will not occur, but if I select a item again in combobox3, "Object cannot be cast from DBNull to other types." will occur..
here is my code
Private Sub ComboBox3_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ComboBox3.SelectedIndexChanged
[code].....
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Oct 17, 2009
Guys,this is my first day at the forum,and my second thread. Can someone explain me how can i make an axshockwaveflashobject2 to copy what happens at axshockwaveflashobject1 like a picture or video. I have a tabed trainer and i want to see my stats in game at the second tab. i have the hack menu on a toolstrip,but i have at the tab 2 flash1.get variables to textboxes,but i can't see what's happening at the flash1,and i may lose the level by falling in the sea. The code should make something like a mirror from flash1 to flash2 at the other tab.
[Code]...
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Apr 27, 2009
Essentially what I want to do is copy a WebBrowser object such that I can do the equivalent of "Open In New Tab" or "Open In New Window" actions, maintaining any posted data. I don't just want to navigate to the same URL as in the original WebBrowser object, rather I want to repeat the HttpWebRequest.
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Jun 23, 2012
I need to compare two dictionary values if the types stored are equal, this is what i have
if gettype(Args(key)) = gettype(argtypes(key)) then
'' do something
end if
[Code]....
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Jun 15, 2012
I am having a problem when setting VB.NET list object to another.I create an instance on ReadLocations and than create an object of ReadLocation where then I loop through ReadLocations and set ReadLocation1 equal to rl. What happens is that if I then go and change ReadLocation1 to something else (assdfhsd) it will also change the ReadLocations index. I am really confused why it would be doing that unless it is "=" sign means referencing instead of actually setting the value. Please help as I am a C# developer but the program I am modifying is in VB.NET.[code]
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