I have a Clients master object and then a number of child objects whose exact number is not known in advance such as Client-Contacts, Client-Payments etc, all of which have a one-to-many relationship with the Client master object.How do I define classes for such a scenario? Do I for instance create the master Clients class and can then I create an array of class somehow for child objects?
View 2 RepliesI have a nested class, let's call it class1 and it has class2 inside it; VB.Net eg:[code]
1) How can I define X number of Class2 objects[let's call it: Node(x) array]** with NEW() subroutine called?' this raises error: dim cls2(n) as new class2 end sub.
2) How can I return actual number of Node() array? [code]Outside my class in main project I define cls1 object:[code]Now an array of class2 is created inside cls1.
3) Now,How can I access All of them[node(x) array which is created inside cls1] with all properties and methods available?
I remember I wrote a ProcessManager class with this functionality in .net 2003, nearly 4 years age, I don't have the code now.
1) Add a Private variable named _area2) Associate the _area variable with a Property procedure called Area3) Change the CalculateArea method to a Sub procedure. The method should calculate the area and then assign the result to the _area variable.4) Include a parameterized constructor in the class. The constructor should accept one argument: the side measurement. After using the Public property to initialize the Private variable, the constructor should automatically call the CalculateArea method.At this point I believe I've completed the first 2 steps for the Square method, but I'm not sure where to go from therHere is my code for the Square class and the Main Form, in tha order:
Public Class Square
Private _side As Integer
Private _area As Integer
[code].....
I'm wondering on how you would go abouts instantiating a class that contains other complex objects. for example an Payment Class which has Date,Time, etc.. and it also holds a reference to a paymethod object which has id,Type,Description etc.. How do you instantiate the payment class with all the other objects without one or the other failing, how do you create the payment class which doesn
View 4 RepliesIs there any way to use a LINQ to XML to query an XML document like the one below to create new (anonymous or strongly typed) objects from the child elements of a descendant? Here is my XML document:
[Code]...
long story short, I have created a ListView type control, using UserControls for the parent control and the ListViewItems. Most the of the control is written and works fine, right up to the point where I tried to replicate the 'Control.SelectedItems(0).Index' property and the 'SelectedIndexChanged' event.
Each child object knows its index value, and could pass this value via the SelectedIndexChanged event (assuming this is how it works in a normal ListView control -- user clicks on an item, and that item fires an event updating the selected index value in the parent object).
How does the child object raise an event in the parent object? I have a feeling this could be done with Delegates, but I'm still learning about their usage.
Dim obj_DataTable As New System.Data.DataTable("Category")
Dim obj_DataSet As New DataSet()
'Declaring the array of DataColum to hold the Primary Key Columns
[code].....
I'm trying to wrap my head about how to properly implement an OOP design for business objects that:
Have a "master list" in a database (ex. classifications)Are a part of another object as a property (i.e. object composition) but with additional properties
Here is where I'm stuck on the theory. Suppose that I have a Classification object, inheriting from the abstract class BusinessObject with the CRUD functions defined (MustOverride). This will give me:
[Code]...
What kind of other design could I implement here? It's obvous that I'm designing this the wrong way, but I don't see an easy alternative pattern. I don't want to repeat the code in the CustomerClassification class by not inheriting Classification and repeating all the field and property code, but I also don't want to expost CRUD functions to the CustomerClassification level. What am I missing in looking at the overall class design?
EDIT: Saving the classification level to the database will be handled by the customer object, because the database is legacy and the field for Level is defined in the customer table.
I created a dataset.xsd and it contains two table adapters and these table adapters use stored procedure for select.in my vb form, i get value in text box and then fill table using tableadapter and pass parameter to sp. Till this point everything is working fine. Now these tables have relations and i want to create relationship and show the data from child table on basis of master table. How i can do it?
Example
Me.MasterTableAdapter.Fill(Me.dataset1.spMaster, 1) --1 is parameter which is passed to sp
Me. ChildTableAdapter.Fill(Me.dataset1.spChild,1) --same parameter is passed to child table.
Now i have the records in spMaster and spChild. how i create the relationship so that when i move thru Master the child have corresponding records?
I have a form that is set up like a master/detail form - fields on top with a child grid below. The difference here is that the child grid is reflective of a recursive relationship. That is the ID of the master has a one-to-many relationship with another attribute called "parent." the child grid displays all the children for that parent. It works properly except when a new record is being added to the master.My issue is that when the user clicks on the Add New button, the child grid then displays all the available parent records in the system instead of an empty grid. Once the new master (parent) record is saved, the grid reverts to proper behavior.Thus, my question: How do I prevent the child grid from displaying all the parent records when a new master (parent) record is being added?
View 1 RepliesThe 1st part of the code required me to write a class definition for a class(Worker). The class should include Private variables and Property procedures for a worker object's name and salary.
The salary may contain a decimal place. The class should also contain two constructors:a default and a parameterized.
The second part for the code indicates that I need add a method named GetNewSalary to the Worker class.The method should calculate a Worker objects new salary, which is based on a raise percentage provided by the application using the object.
Before calculating the new salary, the method should verify that the raise percentage is greater than or equal to zero. If the raise percentage is less than zero the method should assign the number zero as the new salary
There are three text boxes which allows the user to enter the employees name current salary and raise percentage....the calculate button will display the new salary in the new salary label box...so far here is what I have for the worker class.
The Class for the code had to be written from scratch. Can you please look over the class code and see if I need to chang anything....that will allow the program to run.[code...]
In ASP.NET I have a form that has a Textbox named txtOutput and a button. In the main file.aspx.vb I can call a function from the button handler and in that function I can have [code]I have a bunch of functions in several other classes. For instance I have a class named AbleCommerce that does some database functions. These functions are called from my main class. In those functions, however, I have no visibility of txtOutput.All of my classes are, unfortunately, in the default namespace which I understand is not optimal but didn't seem to impact this issue.
View 2 Repliessuppose I have a collection of objects of different classes (like controls in a form), and all of their classes have a MyMethod extension method. How do I have the appropriatemethod be called for each object, depending on its type?or example,
For Each ctrl In Me.Controls
'call ctrl real type's MyMethod
Next
[code]....
Pursuing the Microsoft Certified Professional Developer Certification and working through the training kit.I've programmed for a while and mainly used classes as my objects.The training certification book I'm working through has a section on structures. they look very similiar to classes so my question is: why use them? Do they offer something that creating a class doesn't? What's the difference between structures and classes?
View 8 RepliesI've been trying to understand classes and objects. Yes, I'm thick headed and slow, but I made the decision to go to .Net and I am determined to improve my coding skills to be more efficient. I have spoken to Atma several times on the topic and read most of his posts concerning classes and objects, but still came away a little baffled (He's really advanced for me yet). I needed a simplistic analogy for a reference point to begin understanding. I was reading about OOP written by MikeJ in the following thread/post ...[URL] and it all started to become clear in this statement , but I would like some reassurance that I'm getting it ..."A car IS-A vehicle, while a dog HAS-A tail. The car would be an object declared as type Vehicle, while the dog would have a member that IS-A tail. However, Fido IS-A dog. The dog class is the base template for all dog objects, so when we declare Fido as a dog, Fido is an object. Since Fido IS-A dog, Fido HAS-A tail."
From this I have taken the following understanding...
Vehicle ... ' Class
Car ....... ' Object
Truck ... ' Object
Van ....... ' Object
And from that can I infer that this is true?
Dog ....... ' Class
Fido ... ' Object
Tail .. ' Member of Fido
So to apply this to a program I wrote recently that tracks Generator service...
Generator ' Would be the class
Brand X ' Would be an object
Spark Plug ' Would be a member
Gas Tank ' Would be a member
Brand Y ' Would be an object
Brand Z ' Would be an object
This statement also helped ...
""Class" and "object" are sometimes used interchangeably. However, classes describe the structure of objects, while objects are instances of classes. Each instance is an exact copy of its base class. Because an object is an "instance" of a class, the act of creating an object is called instantiation. To describe it better, a class is a blueprint, and an object is a building based on that blueprint". I can understand this (I think) and it refers to a basic template such as ..."Generator" (my class or blueprint or template) Generators have an engine, powerplant, fuel tank, etc. These are basic requirements to be a generator. (Template or Blueprint) They can differ by Brand of engine, Size of powerplant, and type of fuel used. (Based on template or blueprint) Do I have it down now? MikeJ also made this statement ..."you can't access certain types of class members from outside of the class itself." From this I assume you would need to assign a Global variable the value of the class member if you needed to use it outside of the class?
relation between Classes and Objects with an example.Md. Marufuzzaman
View 7 RepliesI have a webservice that is wrapped up by a data access object and is accessed by many different UI controls.
The proxy objects look something like this:
Public Class WebProxyObject1
' Common properties, there are about 10 of these
Public Name As String
[Code]....
I have one class with <Serialize> attribute called Tree. And Tree class has an arraylist of TreeNode classes. Is it possible to use Soap to convert the Tree class and arraylist of TreeNode classes to one xml file or binary file? If it is possible, do i need to use <Serialize> attribute on TreeNode classes too? If not, what should i do then?
View 3 RepliesI have a project where a email is sent when the user clicks send on the web page, however the content of the email will change depending on what is inputted by the user. I have added classes to my project so that depending what is selected by the user different classes are selected and as such different emails then sent from the project.
[Code]...
I have a program with a base class and classes that inherit the base. A Windows Form will call a function of each child class which raises an event from the base class. The function call to the first child class works fine: the event is raised for the first child class.
[Code]...
I have a VB.NET web app that is about 2000 lines of code, contains about 20 different subroutines, and about 50 different functions.Is there an easy way to "rewrite" this to take advantage of classes and objects?
View 5 RepliesThis probably sounds daft, but im struggling to get to grips with Classes/Modules/arrays and objects, as well as there uses and what they are, and yes im still coding some how i hear you cry.The reason i ask is because Ive got a load of Dim's in my program that are the same giving locations of files and folders and wondered can they be used as a module that i can alter after the program is built, incase of folder locations being wrong or moved, manually correct after install.
View 1 RepliesI have two Parser classes that inherit from a base class, BaseParser. I want to use either class as a parameter in another Monitor class. The Parser classes, CS600 and TCH600, both have two properties, RawDataList and SummaryDataList. The CS600 class's RawDataList returns a List(of CS600Data); the TCH600 RawDataList returns a List(of TCH600Data). The SummaryDataList returns similar classes in each Parser class. CS600Data and TCH600Data derive from a base class, BaseData.BaseParser also has RawDataList (List(of BaseData)) and SummaryDataList (List(of BaseSummaryData))The Monitor class has a private field, _thisParser which can be either of the two concrete Parsers above. I want to be able to call and use RawDataList and SummaryDataList of _thisParser within Monitor class, but when I construct the concrete Parser classes, Visual Studio notes that the RawDataList property of CS600 cannot override the RawDataList property of the BaseParser because they differ in their return types.
I thought that since CS600Data derived from BaseData (but also adds some new properties of its own) that I could use CS600Data wherever I use BaseData. What am I misunderstanding? How can I correctly construct these classes?
Public MustInherit Class BaseParser
Protected _rawDataList As List(Of RawGasData.BaseData)
Public MustOverride ReadOnly Property RawDataList() As List(Of RawGasData.BaseData)
[code]....
When attempting to create a UserControl type that must be inherited, when I try to edit one of its child classes in the Form Designer, I am not allowed to edit the child UserControl with the message:
To prevent possible data loss before loading the designer, the following errors must be resolved:
1 Error
The designer must create an instance of type "XX_ExpandContentsPanel2.IOCardMaster", but it cannot because the type is declared as abstract.
This error goes away if I remove the "MustInherit" restriction.Is there some way around this or do I just have to accept the (bonkers-mad) restriction, and not declare my class as as MustInherit, even though it's not a useful control in its own right?
I am creating a tool that interfaces with an API for a CD/DVD burner. I have created several custom classes that will hold the information for the disk sets (which consist of a data path and a label file among other information. The DiskSet class has a list of Include objects. My proposed XML output would be something similar to the following:
<DiskSets>
<DiskSet>
<Name>MySet 1</Name>
[code].....
I am attempting to traverse the Includes collection (I have tried List and Binding List as I am also using this in a pair of datagridview controls) and it keeps returning Expression of type 'Object is not queryable. Make sure you are not missing an assembly reference and/or namespace import for the LINQ provider." How can I use LINQ to pull a list of the Include objects under each DiskSet object for transformation into XML? I am hoping to keep this restricted to this one block of code if possible.
I'm getting this error 'column' argument cannot be null. Parameter name: column at the bold character instruction. Also I would like to know how to relate two tables with two key columns in each table
Dim connection As New OleDb.OleDbConnection(strTextoConn)
Dim EnPartesdataSet As DataSet = New DataSet("Enpartes")
Dim strsql As String
[Code].....
I've created managed code to programmatically provision websites on Windows 2008 servers from a Vista 64-bit workstation.The provisioning covers creating DNS entries, creating a file structure and a the IIS7 site (using Microsoft.Web.Administration aka MWA).I've had to do some DCOM configuration to get it to work through a firewall and it all works on the test server provided I'm in the same domain.I then cloned the Windows Server 2008 Virtual Machine (VM) that the provisioning does work on and then changed the clone's domain to the child domain in the forest where the production servers are sitting.The provisioning user credentials are synchronised on the parent and child domains.So the only change is moving domains and there is an automatically configured trust relationship between the domains.
Provisioning the file system still works on the server on the child domain, but managing DNS and IIS7 now have access issues.I've tried impersonating the Administrator on the child domain (and the thread identity is showing that works) and also had a go with CoInitializeSecurity (though I'm not sure that is appropriate for Win2008 and Vista)to no avail.What I really want to avoid is the need to have to store credentials separately on the workstation - it brings an unwelcome maintenance overhead and the possibility that if the provisioning user's password is changed, then the provisioning will unexpectedly fail on the production servers.Ideally once the provisioning user has logged onto the Vista Workstation, I'd like their credentials to pass through to the servers on the child domains (there are separate DNS and web servers) allowing them to manipulate whatever services (DNS, IIS7, file system) that are necessary.The solutions would seem to be something programmatic (whatever replaced CoInitializeSecurity?) or a Group Policy setting on the child domain may need altering to allow access.However being a humble software developer working out which of the myriad settings (one of the User Rights Assignments perhaps?) is outside my sphere of knowledge.The third alternative is to use Windows Communication Foundation (WCF) but I haven't done much with this yet and what I have indicates that this technology has its own security issues to accommodate.
Basically I have the follwing:Dim ctx As New AdminCoreEntities Dim roles = (From r In ctx.Roles where r.Name.StartsWith("cust") Select r) 'list of System .Linq.IQueryable(Of AdminCoreModel.Role)
[code]...
The error i get when i run this is: Unable to cast object of type System.Data.Objects.ObjectQuery`1[AdminCoreModel.Role] to type AdminCoreModel.Role
Basically I have a many to many situation and I try to get all the Quicklinks objects queried by their roles and not quite sure why EF will cast to a single AdminCoreModel.Role when i.Roles is a collections of objects.
I am developing a new class which is a control that inherits from the "Panel" class. In this new class, I have three objects that are generated every time I create a new instance of the class. For simplicity, I will call this class "garage" and the three objects "BMW," "Lexus," and "Acura." So each new garage has three types of cars.
how can I share a variable from the Parent class with all of it's child objects? i.e. The garage has an array variable called "tires" which all three cars use. Rather than create each car object with the tires parameter, I would just like to keep the tires parameter in the parent class so that all my child objects can use it. I know that normally the parent class should provide the child class with all information when creating the child but it would seem redundant to pass the entire tires array each time since all three cars use the same tires and the tires object never change.
I coded a class that scans an object and maps data from a data table into each one of the corresponding properties, it works very well, however I am not able to set the property of one of the child (coplex objects)
Public Class CntrConfHdr
Private m_CntrConfHdrID As Double
Private m_HeaderCode As String
[Code]...
I want to set the value for the child object TypeCurrency.TypeCurrencyID thus I set the value of the variable sTargetPropertyName to TypeCurrency.TypeCurrencyID but the application willnot work stating that the property can not be found.