.net - Set An Incrementing ID Property To A Class' Collection?

Nov 15, 2011

I have some nested objects arranged like this:

Process
Persons
Workflows
Tasks

So you have one Process. Then multiple Persons can be added to and multiple WorkFlows can be added Process as well. Multiple Tasks can be added to each WorkFlow but I need a way to tie which Person is doing each task. I basically need a way that for each Person added to the Process it, in it's constructor, assigns a Person.ID property that can then be assigned into each Task's PersonID property...

Dim myProcess as New Process()
Dim myPerson as New Process.Person()
myProcess.AddPerson(myPerson)

[code]....

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Adding A List (of Class) Or Collection As Another Class's Property

Apr 2, 2010

I'm looking for a tutorial on how to Adding a list(of Class) or Collection as another Class's Property.What I am after is something like the Columns Collection for the DatagridView control.I would like to add Items in the graphics screen. Where the item list is displayed in the left panel and the selected Item properties are displayed in the right panel.

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A Property In A Class Is A Collection Of Objects

Jan 29, 2009

Thought I had got this sorted earlier but unfortunately not. A property in a class is a collection of objects.

[Code]...

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Retrieve A Property Of A Class As A Collection?

May 26, 2012

I'm working on a small project and got into some troubles trying to keep it OOP.I have a global variable:

Public Stations As New Microsoft.VisualBasic.Collection()
And 2 classess: Station & Unit:
Public Class Station

[code].....

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Alter Items Added To Generic Collection (as Property Of Custom Class)

Jun 19, 2009

I have several custom classes in a VB.NET (VS2008) project which are related to each other through generic list collections. The lower tier classes refer directly to some of the parent classes (to make it easier to refer backwards up the chain). My question is, is it possible to add the reference to the parent class when the item is added to a collection, when that collection is a property?

Below is some sampling of code to illustrate.
Public Class FlexServer
Private m_FlexLicenses As List(Of FlexLicense)
Private m_Modules As List(Of FlexModule)
Public Property FlexLicenses() As List(Of FlexLicense)
[code] .....

In the code above I have the FlexServer class which refers has two lists as properties, one for FlexLicense and one for Modules. The FlexLicense class has a property to refer back to the FlexServer class that "owns" it. In order to update this property in code, I have to add the FlexLicense to the FlexServer.FlexLicenses list AND set the FlexLicense.FlexServer property. What I am looking for is, is there a way (in the property definition or wherever) to both add the item to the list and alter it at the same time?

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Class Collection Property - Method - Allow For An Employee To Be Assigned More Than One Work Location

Jun 17, 2011

I am experimenting with a transition from my application built in VB6 to vb.net. I know, about time. At the same time, i am making changes and improving upon the original. One area that I am working on is within my employee class. very standard class, nothing fancy. One change I want to make though is allow for an employee to be assigned more than one work location. Employee has (is assigned) Stores. In reading about collections, it appears they are different in .net (as they should be), but I don't know what the sytax changes will be to implement my changes.

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Sum The Properties Of Two Members Of A Collection Without Doing It Property By Property?

Aug 8, 2011

I've reviewed the links that were offered and don't find an answer. Neither has a lot of searching helped, probably because I can't think of a reasonably short way to ask the question. I hope that I've at least found the proper forum and category.

In my VB 2010 code, I've defined a structure that has about 30 elements. I want to sum the properties (they are all singles) of two members of the corresponding collection. I understand that I can do something like:

member1.property1=member2.property1+member 3.property1 for the entire set of properties of member2 and member3 to produce a completely defined member1 What I wonder is whether or not there is a way that uses fewer lines of code - I know that I can't do:member1=member2+member3, for example.

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Base Class Collection With Sub Class Objects

Jul 19, 2010

[code]The reason that this is a problem is that this is a collection of EventBase objects, but I'm trying to populate it with child classes instead. For example, I might have a JumpEvent class that inherits EventBase, and this is being put into the EventBaseCollection. That means that value.GetType() returns the type of JumpEvent, which as you might guess does not equal the type of EventBase.The goal of course is to simply loop through all of the various events without having to know anything about the sub-classes. Is there a way to determine the type of the base class so that the OnValidate call will work? Or is this just the wrong way to go about it altogether?

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Passing List / Collection From Class To Class

Apr 28, 2009

I seem to have problem with passing a collection/sorted list/ list of strings from one class to another.I am using property procedure to pass it, however nothing is sent to another class. There isn't any error messages either.[code]

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.net - Make A Class Property Behave Like The Checked Property On RadioButton?

Jun 1, 2012

I have a very simple class that holds a few public properties - ID, Text, Colour, etc. and a Boolean called 'SelectedItem'. Just like the Checked property on RadioButtons, only one item can have its SelectedItem property set to True within a particular group. Note: there will be several separate groups (lists), each allowed to have only one item with SelectedItem = True.

My first thought was that I would probably just have to handle everything outside of the class, setting SelectedItem to False for every other item in a particular list when another item was selected. But that seems rather inelegant to me. So I've been trying to think of how this might be done within the class. For example: could I perhaps have a private string property called say "GroupName" - set in the New sub when adding a new instance of the class - and then use a private shared method to set every item's SelectedItem property to False, provided the item has the same GroupName as the newly selected item? I would have a go at doing this but I have no idea how to enumerate every instance of a class from within that class, or whether that's even possible. Is it? Or is there another (better) way to achieve my goal? Here is a cut-down version of what I've got so far:

Public Class ResourceItem
Public ID As Integer
Public Text As String[code]....

As can be seen: instead of instantiating a new ResourceItem and passing that as an argument to the manager's Add procedure, I'm simply passing the details of the new item and the procedure is creating the item from those. I don't know whether this is a good or bad idea - please advise - but I've done it because I couldn't figure out how to make the SelectedItem property only writeable by the manager, so I wanted to avoid having directly accessible objects that could have their SelectedItem property set to True without it deselecting all the other items in the same group. Of course that still leaves the possibility of setting a variable to one of the manager's list items and setting it from there, so I would still like to know how I could prevent that, if possible.

UPDATE: I didn't use the code above in the end, deciding instead to go with Cyborgx37's solution - which seems to work perfectly well for me despite the warnings about best practice. I also realised I would need to use the same class in another scenario where multiple items could be selected, so it was easy to add a Boolean property to the manager to enable that.

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How To Create A Property For Collection

Jul 14, 2009

I have class called "Employee" and I have a class called Department. They have an association. I need to create a colleciton of employees with the creation of a Departmant. I know how to do with using "private" member _AllMyEmployees. But I need to expose this private member using properties. therefore how do i covert thsi private member to a property? [code]

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Having A Class Property Dependent On Another Property Opinion?

Aug 13, 2009

I have the following code:

Public Class MyColorsClass
'Constructors
Public Sub New()
'Empty Constructor

[code]....

However, if the empty constructor was called to instatiate this class then the colortype is not yet set. Therefore, if one accesses the 'IsColorCool' property it will always return 'False'. Now for the sake of this example, I must keep the empty constructor as part of the class.Now I could add some code in the 'IsPropertyCool' to check and see if a ColorType has been defined, and throw an exception if it has not been set, but I don't really want to do that.I also could always move the logic OUT of the property and into a method on the class called 'DefineIfColorIsCool' or something, and make the owness on the caller to make sure the method was called if they want to use the property 'IsColorCool'?

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Designer Serialization Of Collection Property?

Nov 14, 2011

Ive recently written a control called a ButtonRow in VB.NET that allows you to dynamically place buttons on it through a typed collection property. The property itself is tagged with the <DesignerSerializationVisibility(DesignerSerializationVisibility.Content)>. However it works really bad. First of all, whenever you add buttons to it and you delete the controlafterwards, the designer code file still have the buttons declared but without the aButtonRow to who's collection they would be added. Secondly, you cannot copy the controlfrom one form to another. It would just copy the ButtonRow object without the buttons

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Set Text Property On A Checkedlistbox Collection?

Feb 2, 2009

I had read on pages like this

that when adding objects to a CheckedListBox, it takes the .ToString() function of each added object as the text string.

I added instances of SortedDictionary as this[code]...

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.net - Suppress A Property Or Method From A Base-class In A Derived Class?

Apr 7, 2011

Supose a base class

Public Class airplane
Private var_num_seats As Integer
Private var_num_engines As Integer

[code]....

Obviously, I don't wish that the class Glider has the method "start_engines" neither the property "num_engines". Otherwise, other child classes may have. How can I supress these property and method in child class, not just ignoring (if I can)?

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Can't Set DataTable Class Level Variable = Class Table Property?

Sep 29, 2011

I have procedure (Import) that calls a for a new instance of frmImportData. I also have a class name clsBatch that has a data table property called prpParametersTable.For some reason, I get an error (indicated below with ERROR>>>) when trying to assign prpParameterTable to cv_dtImport2. The error states "Object reference not set to an instance of an object.". Why does this error not happen when I assign dtBP to cv_dtImport1? Both cv_dtImport1 and cv_dtImport2 are equal to Nothing and in my Import procedure dtBP = prpParametersTable.

Public Sub Import(ByVal clsB As clsBatch)
Try
Me.cv_clsB = clsB

[code]....

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Class Property Usage - Unable To Retrieve A Variable From On Class

Nov 14, 2009

I have three class files, accounts.vb and transactions.vb in addition to my form.vb. I am unable to retrieve a member variable from on class from inside the other. When the combobox index changes, the program loads the correct account (checking or saving) from two different sequential files. I don't think I have the calcBalance procedure in the correct class file. And that is what I am having trouble with. Accessing it to display it. [Code]

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Items Collection Cannot Be Modified When DataSource Property Is Set

Apr 27, 2010

I am trying to refresh my combobox when an item is selected and added the highlighted code as shown below; [code]Items collection cannot be modified when the DataSource property is set.

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PropertyGrid And CollectionEditor - Object With A Property That Is A Collection

Aug 12, 2011

I have an object with a property that is a collection. When I point the PropertyGrid to the object it displays the ellipses for the collection. When I click it I get the generic collectioneditor. Of course the Add put fails because my collection is strongly typed. I need an example of how to create a collectioneditor that will create my collection's objects.

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Access Members Of A Sub Class Through A Property Of The Parent Class?

Mar 30, 2010

This is a bit of a continuation from a previous post for which AtmaWeapon was very informative.

Problem:
A parent class has a sub class with various properties. A property of the parent class is a List(of T) with T = the sub class The issue is how to store data in the sub class of the instantiated parent

Some example code (hopefully formatted correctly):

Code:
'=========== Class Definitions =============
Public Class courseClass
Public Class timeTableClass

[Code].....

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"Items Collection Cannot Be Modified When The DataSource Property Is Set?

Jun 17, 2010

I have a combobobox on my form, and I use the following code to populate the data from SQL Server:

cbname.DataSource = DSAssetName.Tables(0)
cbname.DisplayMember = "IDWLNAME"
cbname.ValueMember = "FIDWID"

[code].....

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C# - Datagrid: Generate Columns From A Property Of The ItemsSource Collection

Nov 18, 2011

I'm trying to create a datagrid with auto generating columns. Let's say my Collection is a property named Articles of my viewmodel of type ObservableCollection<ArticleWrapper>.

I bind now the ItemsSource to this collection:

<wpf:DataGrid ItemsSource={Binding Articles} />

The class ArticleWrapper is like this:

[c#]
public class ArticleWrapper
{
public ArticleConfigurationSet ArticleConfigurationSet { get; set; }
public string Description { get; set; }

[Code]....

But now my problem: I want to bind the displayed data to my ArticleConfigurationSet property. But I cannot change my ItemsSource Binding, because the SelectedItem property of the datagrid must be of ArticleWrapper (for command handling).

The datagrid should also look like this:

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VS 2008 Items Collection Cannot Be Modified When The DataSource Property Is Set

Feb 13, 2010

I have two tables "Person" and "Alias" in a one to many relationship. I have a DGV for "Person" and want to use a combobox for the Aliases. I also have a textbox and a button for the user to type the alias name and click the button to add the alias name to the combobox and update the dataset. I keep getting the "Items collection cannot be modified when the DataSource property is set." Error. But if i use a DGV instead of a combobox for aliases, I have no errors and everything works fine. If I remove the datasource property for the combobox it will not get populated with the data already entered, so how, or can I, set it up where the combobox gets populated when the form loads and able to add items to the combobox????

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VS 2010 Items Collection Cannot Be Modified When The DataSource Property Is Set?

Aug 26, 2011

Like i want it to read the lines i have in the text file but i get an error Each time i press the button Why?

Private Sub Button5_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button5.Click
Dim objreader As New System.IO.StreamReader("C:UsersJamesDesktopMusicas.txt")
Do Until objreader.EndOfStream

[code]....

Error:

Quote:

Items collection cannot be modified when the DataSource property is set.

Error line

Quote:

ListBox1.Items.Add(objreader)

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Why Use A Public Property Instead Of A Function To Expose A Custom Collection<T>

Jul 6, 2009

During a code review I looked at set of repository classes (in vb.net). I am used to seeing these repository classes full of functions that return collections (among other things) of your domain objects. However, this repository had 1 public property and 1 private variable that looked something like this:

Private _item as Collection (of Customer)
Public Item as Collection (of Customer)
Get...
Set...

In the "Get", there is code that gets a the Customers from the DAL and loads it in the private _item. What would the benefits be in using a property (customerRepository.Item) instead of plain old function (customerRepository.GetAllCustomers)? The "Property" way looks odd to me but odd doesn't always mean wrong.

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Error: This Causes Two Bindings In The Collection To Bind To The Same Property - Parameter Name: Binding

Aug 15, 2010

error in binding

Dadapter = New SqlDataAdapter(dat, conn)
Me.Dadapter.Fill(Me.Table)
bs.DataSource = Me.Table
DgvTire.DataSource = bs
txtserial.DataBindings.Add("text", Table, "serialn")

error: This causes two bindings in the collection to bind to the same property. Parameter name: binding

what should i do with this error?

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Order A Collection Based On A Child Property Using LINQ Or A Lambda?

Jan 26, 2012

I get the following string expression provided:"ChildObject.FullName" ...where ChildObject is an instance property on the MyObject1 type.ChildObject has a property named "FullName" and I want to sort a collection of type "MyObject1" based on this child properties "FullName" value.

I can do this all day long on properties directly on MyObject1 but I run into 2 challanges when doing it on a child instance and I can't get all the pieces working. The main 2 challanges are:

MyObject1 has a few different child property types so I can't hardcode the type for ChildObject. The string could be of any type.The sort expression is a String and not a known type.Above the value returned from the last line in the expression (if I run the code outsode the OrderBy method, does provide me the 'FullName' information I need. So the code must be close, but it still does not work.

Any ideas on how I can accomplish this? What I am trying to prevent is hardcoding a series of 'If' blocks on the child's type to then hardcode in its type to the sort or OrderBy method.

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WinForms - Editing Custom Readonly Collection In Property Grid

Feb 19, 2010

I have a custom collection, lets says COL, that derives from ObjectModel.Collection. I have my own collection editor that works fine when a property, of type COL, is Read and Write enabled. However, if I change the property to ReadOnly, the open editor button stops showing in the property grid. As a test, I override my custom editor with the CollectionEditor, and that worked fine. So, my question is, what check is the property grid making, that CollectionEditor passes but my collection editor fails?

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.net - Accessing Property Of A Class Without Inherting The Class

Apr 7, 2012

I have a class that has the following property that is generated by the methods in the constructor.

Public Class clsLoadTables
Private _ds As New DataSet
Public Property ds() As DataSet
Get

[CODE]........................

My problem is that I do not want to inherit this class, but I have other classes that need to access the ds DataSet property. If at all possible I would like to not use inheritance and not load my datatable more than once in the program.

Here is my failed attempt to access the property inside another class that is not inheriting clsLoadTables:

[CODE].........................

How I can access this dataset that I want to load only once in the program from many classes without using class inheritance or a global module?

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VS 2005 Class Contain Another Class Within It - Interface And Property?

Jul 29, 2010

I know that an interface can contain another interface within it.But;can a class contain another class within it?Can an interface contain another interface within it?

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