Create An Object Of A Class In Which There Are Properties And Functions That Do Database Selects, Updates And Deletes?
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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Dec 16, 2009
Just looking to keep application looking neat, One Form Parent / Child relation, set to cascade updates / and deletes. What I'm looking for is when the form loads the user enters some information for the parent (about 2 column out of 5), then I create a datarow with the information that I have. At this point before I actually send and update command, I would like to get the next scope identity for that datarow.
The reason is I also use that Identity as an Id number in this case a receipt number, and the user will enter detail data that is stored in the child, then calls the save function, this is when I intend to actually call the update to the database.
So the question is, Can I retrieve the scope identity for a datarow that only exist in the dataset without calling the update command and actually storing the data in the database? Or in my case creating my own auto index sub a better choice?
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Feb 24, 2009
I want to create a class (I think) that has properties that correspond to column names in a database table, such that they come up in Intellisense when I type the dot after the class name. Is this possible to do?
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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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Dec 15, 2011
I'd like to have something like:
[Code]...
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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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May 4, 2012
I want to see if there is a way to do this... I'm Using vs2010 with the WP7 SDK. (VB.NET)
I am declaring this in the global scope.
public objGame as object then say i have classes: Game1 and Game2 for the sake of the example we'll just say both classes have an Update() function
I want to set objGame = Game1 (or Game2) and then be able to call objGame.Update()
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Apr 2, 2009
We were working with a VB.Net app that contains something like 2200 VB modules/forms/classes and got a not-uncommon error message when we went to compile it. (Didn't write down the exact message, but it's basically unable to copy an image file that's in use.)Problem, of course, is that not everybody got out of the app when we told them to. Like I said, not uncommon. (It's a shared app that runs from a server.)Now, the weird thing. After kicking the offenders out, when we recompiled the program the image, which we use on search buttons, was gone. The file was still there but all of the property settings that referenced it were gone. Looked into the Designer code & they were gone from there, too. Seems to me that a compiler should *mark* the code that won't compile, not delete it.Anyway, I only see two courses. Either we restore our app from a backup, losing all our changes, or we go thru all the forms (like I said, there are 2200 modules-not sure how many are forms, but it's a bunch) and manually replace the properties on all the search buttons. Either way it's going to cost us at least a day's work.
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Nov 20, 2010
I have a property grid and I want to be able to set the selectedobject to a class. The class contains properties. This is what I have, but it 'OtherFiles' is not an object.
pgProperties.SelectedObject(OtherFiles)
How do you create a class as an object. In VB.NET 2008 please. C# is ok.
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Dec 6, 2010
What I am trying to do is have a class where the functions of the same name are both instance functions and shared functions.
Public Shared Function Get...(byval xx as xx)
and
Public Function Get...
The Public Function uses a Property xx created in the constructor, whereas the Shared Function has the parameters (byval xx as xx).
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Mar 6, 2010
I'm wondering how I can go about creating something like a header file to contain some verbose functions I don't want to have to look at after I get them created. Something like in c++ like..
#include "classfunctions.h" to hide all the nasty stuff you don't want anyone to see.
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Jun 10, 2009
I am moving from VB to C#. I am trying to loop through a collection class which is a collection of data classes but I can't seem to get the actual values out of the data class properties(find the correct code to do so). I have a method that loops through the collection class(Contacts) and saves each record(Contact). I am using reflection because my method will not know if it is Contacts class or a Customer class and so forth. Here is my code in VB(watered down)
Public Function SaveCollection(ByVal objCollection as Object, ByVal TableName as string, ByVal spSave as string)
Dim objClass as Object
[Code]....
The C# code keeps returning null. In my locals window I can see the proprties on the class on objClass and the value of the propery but I can seem to figure out how to access it through code. I used the DictionaryBase because that seems to closely match would I need to do. My data class(Contact) has a bunch or properties that match the field names in the database of the Contact Table. After I get the propInfo variable set I then set up my SQLParameter with the fieldname, datatype etc and then set the value to the propInfo.value.
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Apr 28, 2009
how to create an instance of a class then add properties to the class, set those properties, then read them later. I don't have any code as i don't even know how to start going about this. C# or VB is fine.
My system has a dynamic form creator. one of my associates requires that the form data be accessible via web service. My idea was to create a class (based on the dynamic form) add properties to the class (based on the forms fields) set those properties (based on the values input for those fields) then return the class in the web service.
additionally, the web service will be able to set the properties in the class and eventually commit those changes to the db.
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Oct 2, 2011
I am learning vb.net and I am having trouble wrapping my head around the following... I can create several properties of a custom class and get/set values or I can create a method to set them all at once. If each property is going to allow read and write should I just make a method to assign values all at once? I assume that I am missing a very important piece here. Example: I can create 2 properties:
[Code]...
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Oct 15, 2009
i have several classes / objects from it in a program that hold data like clsAddress with properties id, city, zipcode, name, and clsMyData that contain id, datafield1, datafield2, datafield3 and many more (just examples) I want to have methods in the objects to load the object from and save the object into a database, like me.loadFromDb and me.SaveToDb Of course i can do creating db tables like tAdress, tMyData, ... and in the methods do select / insert statements like "insert into adresses (city, zipcode, name) values(me.city, me.zipcode, me.name) etc. BUT - what i dont like is a) i need to build this loadfromDB / saveToDB Methods for every class separately and b) whenever i alter a class, i must alter the DB structure and the methods.
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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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May 11, 2010
I'm trying to make a very simple audio tag editor. The idea is that the user can select as many audio files as he likes from a ListView, and a PropertyGrid will then display their tags + their values.When multiple files are selected, I want the property grid to display the values of the tags that all files have in common, and display empty values for tags that the files do not have in common.As an example, look at the properties list in your Visual Studio IDE when you select multiple controls (of the same type for this matter). Select a few Button controls, for example, and notice that the properties whose values are the same (often things like Font, ForeColor, etc) are displayed. Also notice that the values for properties that are not the same (Text, Name, etc) are empty.
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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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Mar 2, 2012
I have a class that represents the table of a db-row. Its properties are the columns of the table. I add a new row to the table with the following code:
Public Sub AddRow(oTestRow As TestRow)
Dim sql As String
With oTestRow
[Code]....
That is just an example, but my classes have around 30-40 properties and this brings a very large and complex sql string. Creating, editing or maintaining these sql strings for many classes could generate errors. I am wondering if any compact way or method exists in order to add the whole object's istance (the properties of course) to the table "TestTable" without writing such a large sql string. I created the TestRow in the way that its properties are exactly the columns of the table "TestTable" (with the same name). But I did not found in the ADO.NET anything that could be used.
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Jul 22, 2011
I wrote a sub that would update an Active Directory user's phone numbers using the lines below:
SetProperty(dirEntryResults, "telephoneNumber", strPhoneNumber)
SetProperty(dirEntryResults, "mobile", strPhoneMobileNumber)
The telephone number updates successfully but the mobile number never updates although the strPhoneMobileNumber variable has a valid phone number value. The code executes without any errors. What do I need to do to change the mobile number?
Sub UpdateUserAcct(ByVal userLogin As String, ByVal strPhoneNumber As String, ByVal strPhoneMobileNumber as String)
Dim dirUser As DirectoryEntry = GetDirectoryEntry()
Dim dirUserSearcher As DirectorySearcher = New DirectorySearcher(dirUser)
[code]....
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Sep 21, 2010
I have a need to populate a data object containing 30+ properties from a database table. I could create a simple class containing a public variable for each of the required properties, but I don't want to.
Is the following code a bad idea:
<Serializable()>
Public Class DtoEmployee
Public EmployeeId As String
[Code].....
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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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Apr 23, 2009
Using Visual Studio .NET 2008 or 2005, is there a way to automatically generate properties for each column in an SQL Server database table? I am assuming other code-generation software exists that will do this. I know with Visio I can connect to my database and it will generate diagrams by table, this would be similar to that.
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May 15, 2011
I try to do a very simple job which is: Delete a row in dgv AND database! But now after three days I'm running out of steam
The problem is: I select on or more rows in dgv and push the del button. The sub zDelete starts working and at the end the selected row is gone and the row after my selection is gone too!?!? The deletion of the selected row was well done in dgv and database. But why is the next row in dgv only also disappeared??? After a restart of the form the missing row is back up again. And when I try to delete the last row it trows an exception error: System.IndexOutOfRangeException was unhandled
The code fragment is this:
'Delete all selected rows in dgv AND database!
Private Sub zDelete()
If MessageBox.Show("Do you really want to delete the selected rows?", "Delete", MessageBoxButtons.YesNo) = DialogResult.Yes Then
[Code].....
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Aug 28, 2010
Frontend: Visual Basic.Net VS: VS 2010 .net Framework: 4.0 Backend: MySQL 5.0. Everything is working well, add/edit/save. I am using datasets to manipulate the database the forms are created by wizard and i drag and drop the details over the form. The Problem: I delete a record on the form, it disappears (it deletes it from dataset i think) but i go to the database it is still there also if i close the form and re-open it the records re-appear.
There is something i do but it raises an error, after deleting the records i hit the save button,the following comes up. Transaction has already been rolled back or is not pending after that the records are really deleted.
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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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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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Mar 1, 2010
I need to create unit testing project for my current website. The currentw ebsite si written in VB. All unit testing examples are using interface to create mock object. My current VB class does not implment any interface. Can I add interface and implement it to my current class and functions without affecting or changing codes to any pages in my website that call the functions? For examples my current class is like:
[Code]...
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Feb 21, 2009
I'm trying to create a for loop that will display the values (favorite programming languages) a user selects for a listbox.
So far I have this:
Dim selectedLanguages As String = ""
For intLoopIndex As Integer = 0 To languageListBox.Items.Count - 1
[code]....
So far, no matter how many items they select it will display a comma even if only one item is selected, example "C#,"However this is what I need it to do:
1. If the user selects one programming language than it should just printout the selected course with a period right after it. Example: C#.
2. If the user selects two languages it needs to have the text "and" between them followed by a period. Example: VisualBasic.Net and C#.
3. If the user selects three or more languages it needs to seperate them like this for example (again with a period at the end): VisualBasic.Net, C#, and Asp.net.
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