Create An Object From The Class - Use The Object To Interact With The SQL Db?
Apr 12, 2006
I am developing an IT Asset Tracking application using VB 2005 and SQL Server 2005 Express edition. Will I need to create classes to represent objects such as Computers, Printers, Scanners/Faxes, Contracts, Purchase Orders etc or are there any other approaches.For example, if I am correct, I will have a class called Computer and its properties will include Make,Model,CPU,Hard Disk,Memory etc. Is this the right approach.
Computers can be split up into Desktop PC's, Servers and Notebooks. Would I have to create separate classes for these as well or would they be ok under the Computer class.Once I create an object from the class, how can I use the object to interact with the SQL db.I am a beginner to VB.NET 2005 therefore I am slowly getting to grips with OOP.
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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, 2011
So I am currently using the method of combining a timer with a WebBrowser control to constantly check if some particular text has appeared in the WebBrowser control on my form. The text is dynamically generated after some arbitrary amount of time depending on the user's internet connection speed. (I'm using DOM to do this). The code to check for the HtmlElements lies within a function, which is turned called by the timer.
I find that this is kind of crappy and occasionally lags the UI interface, if not making the entire program behave sluggishly. I have been thinking of just using a simple while loop in a worker thread to take care of the issue, but I understand that new threads cannot interact with the UI thread directly (including controls); they have to call wrappers that are present within the UI thread.
So my question is, can you declare a WebBrowser control and still interact with its HTMLDocument properties if you declare it within a worker thread? I don't want the while loop to be executed within the UI thread (by using a wrapper), since that would defeat the purpose. I would also like to avoid DoEvents() as much as possible...unless that's the only way to do this thing?
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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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Nov 28, 2010
I want to create a class is it where I can do...
[code]...
How do I do this? Do i create a class and create a instance of CarData? but how do I add Color and Year etc to it?
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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 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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Sep 29, 2011
I am trying to create new variables inside a class after creating its object at runtime. The problem is that I don't know the variable names or the value beforehand so I have to create the new variables at runtime.
[Code]...
This is a more elaborate explanation of my code. If you observe that in the Eval function I have tried to evaluate Fval(abc). Now the object array abc is not declared in the Test class because it existence is not known beforehand. What I want to do is create an object array abc of length 2 and populate it with some values and when Fval(abc) is called then then the value of index 1 should be the return value of Eval fucntion.
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Jul 13, 2009
I have created a synchronized queue and am using SyncLock on the SyncRoot property of that queue when I invoke the Enqueue/Dequeue methods. The methods are invoked from instances of standard producer/consumer classes.Is that a proper use of the SyncRoot property?
Would it be better practice to create a private shared object in each class and lock on that instead?
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Oct 26, 2009
I have an object that is defined as a global variable based on custom class. Within that class I have an event that gets fired a certain intervals. These events are fired on the same thread as where the object is declared. How do I create a global object, but have the events within that object fire on a separate thread?
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Jan 12, 2011
I am trying to write an VBA application in Excel 2010 using "Microsoft Soap Toolkit 3.0" on 64 bit Windows 7 to consume an web service. But i got an error while initializing an object of SoapClient30.
Error message is :: Runtime error '429' :ActiveX component can't create object.
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Dec 12, 2011
I want to start building my first large program. I want to create scripts on their own and allow them to interact with my main sub. I guess if I need a "plane" in my application, that could become it's own class? If I wanted to calculate "purchases", "money" I could create a DLL? I don't want to have to change things and have to recompile my entire application every time I want to change how something works for example.
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May 3, 2011
I was create Access database with Access 2003. I create VB project with Visual Studio 2005 Standard With connection wizzard I create coonect with this Access database, select all tablesI see this database inside Data sources and inside Server explorer Test connection is OK When I drag and drop table from Data sources, Wizzard don't create DataGridView, DataSourceBinding etc .. and I see popup window with mesage: Object reference not set to an instance of an object and then "game over"
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Sep 6, 2010
String s = "test"; String is a class, so to use it we should create an object of it. But rather we just make a reference of it and give it a value. How is it possible and what concepts are used in it. The metadata of String class shows the following :
[Code]...
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Sep 21, 2009
Under component services, a COM+ component is used by the company, right-clicking it and choosing 'Activation' tab will show the 'constructor string' that is used for DB server connection by all applications. How can I access it the simplest way possible?
[Code]...
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Nov 12, 2010
I have a class library that contains a number of classes. I would like to dynamically create an instance of one of these classes, set its properties, and call a method.
Example:
Public Interface IExample
Sub DoSomething()
End Interface
Public Class ExampleClass
[Code].....
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Jun 3, 2009
i have drawn on a e.graphics object and now want to transfer the drawn stuff onto a bitmap object how can i do this?
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Oct 22, 2010
how to implement UI, BL and DAL in a project the way that I see it as a requirement for some projects. The way I am able to do a project now is from a form create an object of a class in which there are properties and functions that do database selects, updates and deletes. Looks to me that doing a project like that is separating the UI from the DAL. In an update button click event I may call Obj. Delete (txtCustID.txt) for example. I don't understand the part of further breaking it down to include a Business layer; in which a vb solution is made up of three solutions.What goes in the BL?Does the BL call the DAL?
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Oct 5, 2009
If you want a instance of an object to be created when a form loads or another class is created, you have two options:
Public class example
private IAmAObject As IAmAObject
public sub new()
[CODE]...
Or like this:
public class example
private IAmAObject as new IAmAObject
public sub new()
[CODE]...
I always use the first one. It's more type work but I think it's neater. How about you people and is there any real difference between the two?
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Feb 29, 2012
I am attempting to create a new mobile app using VB in visual studio 2008. I select "File" "New Project". Select "Smart Device" in new project window. Select the "Smart Device Project" from templates. Select ".NET Framework 3.5". Select "OK" and get the dreaded "object reference not set to an instance of an object"
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Mar 17, 2012
The book "Beginning ASP .NET 4 in VB 2010" contains the following:NOTE: TaxableProduct inherits from Product.You can also cast in the reverse directionfor example, cast a Productreference to a TaxableProduct reference. The trick here is that this
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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 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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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.
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