Making OOP Via Observer Paradigm And Easily Adaptable To Test Driven Dev't
Apr 25, 2009
How to implement an observer pattern in VB.NET?
Currently I have a lot of working code in VB6 which the company wants me to migrate to VB.NET. Well, that would normally be straightforward ... yes? Unfortunately, not so in our case.... recently, our company decided that I need to modify it to implement the MVC (Model View Controller) paradigm to make it truly OOP and adaptable to TDD (Test Driven Development).
Currently, my move was to start with a simple one, opening a form and then grabbing a piece of text from a textfile and putting it as the caption of the form... now, that is easy.
The problem lies in trying to implement observer patterns ... in the observer pattern I cannot simply call the usual me.caption = mytextstream.ReadLine from the form_load event instead, I need to use objects that would use an interface to register themselves as observers as the form loads but not necessary having to be residing in the form_load event... in fact ... if there is somehow a way for me to make such a thing happen before the code goes through the form_load event then that would more completely separate the View layer from the controller layer which gets implemented through the use of observers and observer related patterns.
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Mar 9, 2011
I'm still trying to understand and use Use Cases and Test Driven Development, but having a hard time crossing the line. I'm hoping someone can provide a good example of how setting a datasource and/or databinding a gridview could be accomplished using Test Driven Development. Here is my pseudo approach at it.
[Code]...
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Dec 14, 2009
I am making a exe application and i am using mysql as my database. So the thing is, when i change to a new computer, i need to change the file path for the database connection string to that computer.
like below:
Dim connectionString As String = "Data Source=----------SQLEXPRESS;Initial Catalog=Flexlink;" & "Integrated Security=SSPI;"
i need to change the data source = --------------- SQLEXPRESS to the computer name that i am using for my project.
May i ask is there any method such that the user dont have to go in to the source code to change the computer's name like those normal installer?
Just install and the application will run according like any exe file that we buy.
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Apr 10, 2010
So im making a text replacer for PSP Programmers to easily convert the codes to NitePR format. None of you know what that is but w/e Heres my problem I load the text file that has the code into a text box.
Then i press the button to convert. It has this code
[Code]...
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Feb 25, 2012
I am in the process of learning this new programming paradigm called OOP (I am a very seasoned structured programmer). In that context I am receiving what I call contradictions in vb.net regarding the instantiation of an object. Given the two lines of code below:
Dim SQLcmd As New SqlCommand
Dim SQLdr As SqlDataReader
The first line is quite simple - SQLcmd is an object - period. It is the second line that is creating the ambiguity. One reference I have read says in order for a class to instantiate an object the key word "new" must be used. But I have also seen examples where SQLdr is also called an object? To add to the ambiguity I have seen class examples where the class was constructed without a new subroutine (a constructor) and called with the key word "new" which I have been informed by vb.net on more than one occasion in doing such that "there are no constructors" in the class. So would someone please tell me - Is SQLdr an object and if so is it by inheritance (the other escape path) or what; and lastly am I correct in my understanding that in order to use the key word "new" there must be a "new" subroutine/function/constructor in the class.
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Oct 31, 2011
First I dont know how to "link" forms easily. For example: Form1 is like a calculator and I get value X (label.text). How can I "sent" that X to form2? I mean like: Form2.label1.text = form1.label1.text but it doesnt work like that. And I know why it doesnt work.. I dont know how to save that X. Every time I close and open again Form1 I had to start over. So how to save and link forms? Then another: what's wrong with this? Or how I could make it another way? Textbox2 should be numeral (should I code something for it?) and user can set it's value. Now it doesnt show anything in label5. [code]
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Dec 12, 2010
I always have a problem with dynamically generating WHERE conditions to a SQL statement which are base on the nformation given by user (combobox, listbox, checkbox etc.) Here`s an example of how I normally deal with the problem:
[Code]...
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Sep 25, 2010
I don't understand the error, Argument not specified for parameter 'test' of 'Public Shared Function TestThis(test As String)'.
Partial Public Class Form1
Shared Sub ReceiveCallback(ByVal ar As IAsyncResult)
Form1.Invoke(TestThis, New Object(){"test"}) 'error
[code].....
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Nov 19, 2011
I have 3 table which are Timetable, Schedule and Consultation slot and I wish to combine them so that all the data are able to retrieve easily.
Timetable are having
1. TimetableID
2. Lecture ID
3. ClassVenue
4. ClassStartTime
5. ClassEndTime
Schedule
1. ScheduleID
2. LectureID
3. ScheduleVenue
4. ScheduleStartTime
5. ScheduleEndTime
Consultation Slot
1. ConsultationID
2. LectureID
3. StudentID
4. ScheduleID
5. remark
Here is my code in metadata
Partial Public Class CombinationOfTSC
<Key()> _
Public Property LectureID() As String
Get
Return m_LectureID
[Code] .....
I'm having error at c.LectureID = s.LectureID = t.LectureID
I wish to get the combination of 3 tables through the lectureID since there are lecture ID on 3 tables.
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Feb 17, 2012
I have a program that is accessing many similar tables using a linq to sql datacontext. Do linq to sql tables implement a common interface? I would like to write methods that could work with any of the similar tables, so it would be great to do something like
Dim myTable as ILinqDataTable
If switch = "TableA" then myTable=myDataContext.TableA Else myTable=myDataContext.TableB
[Code]...
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Dec 4, 2011
i doing asp.net and using vb.net.I have a datalist control which inside it show a product img, description, price the problem is that i was to show the product another img, so i want to have a small picture below the img, so when click on the picture the img change to another.
i want something similar to this link : [URL]..this link they use flash to come out with the effect that i want, but they are not in datalist, so think that i may need to use ajax but which one?anyone have any sample or example ? if i was to use the jquery easy slider numeric navigation how am i going to implement onto the datalist?
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Jun 11, 2012
Basically, we have three databases to grab data from. One is a SQL Server database, one is an Access database (which is particularly annoying to connect to because we have to map a network drive and such), and the final one will be an Oracle database when IT finally gives us rights.I'm thinking about creating a helper function that makes querying any one of these databases as easy as possible. I want to create a two-dimensional array
Dim myEasyResultArray(10,10) as String
myEasyResultArray = DatabaseHelper("Access", "SELECT * FROM Employee")
Is this a good design decision? Also, how can I have the array be the right size? Can I just do this?
Dim myEasyResultArray = DatabaseHelper("Access", "SELECT * FROM Employee")
Should this be a module or a class? I don't really need to share variables?
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Nov 15, 2010
I want to create a VB program for my final year project,the contents of which can be editable by the user, for example when new information becomes availabe it can be easily added. Now,I thought that this could be done using the text box, although it doesn't seem to be possible.
I plan to use a database to hold the initial information.Could I achieve program 'updatability' in a fairly easy manner?
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Jun 26, 2010
I have an access database with 5 tables.I want to fill a dataset with the entire contents of the database.Why can't it roughly look like this?[code]Instead I'm having to create an adapter for EVERY table, tab the table name (why?), fill the schema, and then fill the table.
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Jun 18, 2009
I need to make basically a bunch of 2d arrays, that I can access the independant values easily. Like multiple properties As an example:
[code]...
Because later I have to access Value1 in a manner that spells out each independantly. I have used some basic Structures to define 1 property and does something with it. But not 2 properties, and I am out of my norm on creating a Class to do something like this.
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Jan 21, 2009
What is a event driven application.
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Nov 15, 2009
I'm trying to construct a database driven VB.Net app that pulls a list of registered accounts from a database and displays the usernames of throes accounts in menu, so the user can select one and a new form open (where they work with it).what I have so far is the constructor for the MDI parent window.[code]What I want to happen is when a user clicks on the context menu a new MDI child form is created and the data in user is passed, however because AddressOf doesn't like passing data this doesn't work.I've looked at delegates and landa expressions but don't think either of them do what I need, the other option is to make my own subclass of the ContextMenuStrip class, which 1) handles the clicks the way I want to and 2) sounds like a nightmare.Before I launch into what I think will be a hell of a lot of work, am I missing something? is their a simple way to do what I want to do? or if not will sub-classing ContextMenuStrip work and if not any ideas as to what will (and if it will, any ideas as to how to start learning how to do that)
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Aug 23, 2011
I'm another newbie with VB (2010) so please bear with me. I am attempting to make a method that is event driven by data threads on the Ethernet port. Simply put, the method is to wait until a data thread from a "Control By Web" 5-input device sends an "information update" data packet to the application, with the application then processing the information. This application is on a private, well controlled network, with no access to the internet. I have a method that is working right now reading data packets when invoked with a timer (see code below) but I really need it to be event driven.
' this is added at the top of the class
Dim tcplistener As New TcpListener(IPAddress.Any, ip_port)
'this is added in the "form1_load" module
[code]....
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Jan 22, 2010
So. I'm making a tool for an online game called Shin Megami Tensei.In this game you can fuse Demons, depending on what family of the first demon you fuse and the second demon you fuse come from, and their levels, the outcome changes.This is unimportant though.
However, the application is driven by a database, the application consists of a Demonic Compendium (Index of the demons, including race, family, stats, levels etc.).This application is meant for usage by the community playing SMT, and here is the problem; a person without Microsoft SQL Server cannot run this application.I can't ask the community, some of which aren't very techy, to install Microsoft SQL Server 2005 Express Edition just in order to run this program.
You see my problem?Is there a way to get the program running on other computers that doesn't have MS SQL Server installed?
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Feb 9, 2010
event driven programming
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Feb 17, 2010
I am trying to build a dynamic validator for a data entry application. I want to be able to query a table for the validators relating to the current task and then be able to reference class properties based on the description of the validators returned.
ex. Validator = "person/firstname"
How do I get to _clsPerson.FirstName?
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Jan 31, 2010
I'm new to programming and am trying to learn how to developed data driven application and was wondering which method is recommended? I know there are some debates out there but most of the books I have recommend using object binding, but it doesn't offer any concrete information on how to implement it. I went to MSDN and most, if not all, the documentations are on dataset. So I guess my questions is, object vs dataset, which do you use?
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Sep 2, 2010
I have developed a windows application which performs a series of database operations like select, insert, update. I am connecting to Oracle database and its working fine in development system. But, when I deployed this application, I am getting error at StartConnection (which opens the DB connection). After installing OracleClient in client system, its working fine. Now, my question is that do I need to install OracleClient to every user? If so, it will be hectic to do so as its size is around 200 MB and its not possible to ask all the users to install it just for a small application. I have tried adding some OracleClient files like orannzbb11.dll, oraciei11.dll, iraops11w.dll etc. But in vain! Could anyone please suggest me a work-around or a way to accomplish this?
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May 12, 2009
I am using VS2008 Pro. I have a simple DVD database built. I'm trying to make a data driven app to store my dvd collection.One of my tables is Actors and is structured as follows.[code]On a form in my app I have a combobox. I'm trying to make it list FirstName LastName ie. Will Smith. I know how to make a query that'll take the LastName and FirstName fields and list it as Actor. I'm having a heck of a time getting it to do that in the combobox as it'll only let me use one field for the display and won't let me use the query I've made.[code]I keep getting some error about schema don't match default query. I know I could simply change the table to only have one field that holds first and last name, but from what I understand that's not proper db practice. I've searched this site and google until I was blue in the face at looking at soulutions that don't match what I'm trying to do.
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Jun 24, 2010
I am trying to have letter templates (word documents) that are stored in sql server VarBinary(max) to be accessed via a web application where they will be edited and saved back to sql server by directors of our company. Then various managers will be able to select an existing template (word document), make any additions, and mail merge with a list of customers to print or save the letters.
I am looking to open up word within a web page much like you would an email in outlook, edit it with spell check and the like, and then save it back in sql server. I am able to get word to open from a file but it is outside of the web application in a separate word document. I am storing the word document in sql server but am unable to open it in word without having to save it to a disk (why should you have to go to a disk for viewing or editing?). I am able to programmatically mail merge but that is in a separate word application.
I am finding bits and pieces on the web but nothing that will pull things together such as embedding word but in a windows app not a web app. Mail merge from a file not from a database, converting a byte array to word in a directory but not on a web page.
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Nov 27, 2011
I want to create a very simple (to begin with) database driven application. The company I work for have very kindly said they will host any SQL database I create, they have a remote server that we all connect to for files etc.
So I want to be able to create an SQL database that they can host and have my colleagues and I install the application local on our machines.
[Code]...
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Jun 28, 2011
I am designing a desktop application that will be driven by local data. I am trying to determine the best way to accomplish this. The database would contain about 10-12 tables if I use a database and I would imagine no more than 10000 records in any one table (but honestly 99% of users would not have more than 1000 records). I am thinking about using SQL Server Compact.
Is this a good solution? I can certainly include this in my installation, but I am just wondering if anyone knows of a better solution? If this is the best solution, how would you suggest that I create the tables upon deployment? Should I just run "queries" with create table statements in them from my vb application or include a database file or what?
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Jun 27, 2012
I am trying to match words driven from a database in a string input using VB .NET
The syntax I am using is so simple:
[Code]...
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Nov 30, 2011
Public Class Form1
Class Member
Public Name As String
[code]....
This is what i have so far and its giving me headaches to fix it someone please help with this code assuming that the names and phone numbers of all members are stored in alphabetical order by last name , then by first name in text file residents.txt
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Jul 19, 2008
How To on a database driven login form. I'll include the Administration Backend to go along with it soon. Dial-Up users should not use this thread, it is image heavy
[Code]...
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