IN my daat access layer, the stored procedure returns value of the format "CCT1". But i need to format that value to "CCT00001". Should i do this formatting in the data access layer or in the business layer?
View 4 RepliesI am generally following this tutorial, the main differences being I'm using 2008 R2 Express and Windows Forms, he is using 2005 & ASP.NET Web Site:'m building a minimalist Windows Form project for learning purposes. So I'm using a 1-table database with 2 columns, ContactID & Name. I added a dataset file, 'ContactsDataSet.xsd' to my project and added a single minimalist table adapter with just a fill() & getdata() method.Then I added a DataGridView control and connected it to the ContactsDataSet to confirm it was working and that worked fine. I ran it and it filled up with data as expected. Everything up to this point was auto-generated code.
View 4 RepliesI have an application that does complex calculations for members. Each member can have multiple US states linked to their profile. Each state has got different calculations for each course a member completes. As of now I have been performing the calculations in the DB (SQL Server 2008) and then sending data back to app layer where they can see their history and then download a certificate for each course. I have a business logic layer but not a lot happens there. I know this has been asked a lot but where do you think I should perform these calculations: business layer or database? I am going back and forth
View 3 RepliesI also went though the whole "ASP.Net in 24 Hours" book by Scott Mictchell. I followed everything that went on in that book and built the final project successfully. I also used the tutorials here to better understand the whole Membership Provider/User tables setup that was going on in the book. Next, I thought I would learn more about accessing data for ASP.Net since that is what most application do.I went through the first Data Tutorial here. I seemed to understand what was going on just fine.The second Data Tutorial seemed to just show a lot of VB code to build the Business Logic Layer. There was not much explanation about how to do it yourself.I think I can keep going in the tutorials here. I downloaded the code from the second tutorial and went through it.I am guessing that the code in the second tutorial was given just to proceed with the overall project that is being built throughout the tutorial sequence.
View 2 RepliesIf code the parameter list as seperate arguments then this wouldnt be a problem, but following a taught pattern that i should take collection as parameters in update or create methods.
Assume the there are three members in a class and in the update or create methods that was told code them to take collection, therefore create.
update methods of that class take collection but the problme the caller faces that it doesnt know the order and names of each element of the collection.
Assume :[code...]
I have a shopping cart ListView control backed by a custom object that has methods for selecting and deleting. In the ListView, one of the columns is an ImageButton that is essentially a delete icon, with the CommandName parameter set to CommandName="Delete".
My issue is related to updating the shopping cart ListView on delete; as the delete method is stored in the custom business entity object, I am having trouble in terms of updating the calculations made inside the cart (we have deleted an item, so I need to recalc shipping, taxes, etc).
[Code]...
I am putting some heavy though into re-writing the data access layer in my software(If you could even call it that). This was really my first project that uses, and things were done in an improper manner. In my project all of the data that is being pulled is being stored in an arraylist. some of the data is converted from the arraylist into an typed object, before being put backinto an arraylist.Also, there is no central set of queries in the application.This means that some queries are copy and pasted, which I want to eliminate as well.This application has some custom objects that are very standard to the application, and some queries that are very standard to those objects.
View 5 RepliesI am implementing a Data Access Layer (DAL), which is basically a set of classes with (VB.NET) Shared functions to actually execute the database (CRUD) calls. I am trying to figure out the best place to place the calls to the DAL within the class hierarchy. Let me give an example.Suppose I have a class Customer, with only standard ID, Name, Address1, etc. properties and maybe an overridden ToString function or so. I also have a DAL class with Shared methods, such as:[code]Would this be "cleaner" OOP? Or is it acceptable practice to let the presentation call the Dal, passing the business objects like my previous example:[code]
View 3 RepliesIm experiencing some problems while attempting to read a connection string from an App.config file in my Data Access Layer.I added the App.Config to the DAL Class Library, and added my connection string to the connectionStrings section but when I try to read it from my DAL its Returing Nothing.
[Code]...
One of the time consuming factors of writing the DAL is adding and assigning paramters of teh stored procedure if ther are more than 10 parameters and must link more than 3 tables this process will take a horrible amount of time..
View 10 RepliesIm writing a data access layer for my application.There are several functions that need to return a list of items like Employee Name, and EmployeeID so it can be bound to a dropdownlist.What would be the proper datatype to return, a Dictionary?The lists only contain 2 columns, a name and id.
View 5 RepliesI am trying to prototype an application with a data layer on my computer at home using Visual Basic 2008 express edition with SQL Server Compact 3.5. My production situation at work is SQL Server 2000 and I am using Visual Basic 2005 professional for development.I am trying to write the code to create a seperate data layer. Here is my code. First the data layer:
Imports
System.Data
Imports[code].....
My Problem is that the data does not show up in the text boxes.
I typically dont create interfaces unless i have to, however in my current application i have to create interfaces in the Data access layer. I'm a in a minor confusion that hwo do i create those interfaces more how to implement them: the following code might make things clear:I have the following class and interface in the data access namespace
[code="vb"]Imports ConsoleApplication8.BusinessLayerImports ConsoleApplication8.DataAccessLayerImports System.DataImports System
Namespace DataAccessLayer
Public Class CountryGateway Implements ICountryGateway
[code]....
1. Is this way implement the interface in the data access layer? (in this case the class CountryGateway access the database.)
2. I have been told that we should create interfaces than abstract classes espcially in the data access layer, is there a particular reason for this?
Our application uses a custom DataAccessLayer class almost exclusively, and within that we do use Data Access Application Block (currently version 2). We are getting the infamous "GetOrdinal" error sporadically. We are not using out-of-method connections. We are using DAAB version 2. Below is a typical example of our DAL methods:
Public Function MyDALMethod(ByVal Param1 As Integer, ByVal Param2 As Integer) As System.Data.IDataReader
Dim db As Database = DatabaseFactory.CreateDatabase()
[Code].....
My main question is should these DAL references be disposed somehow? It's a custom class written in VB.NET, so it doesn't implement IDisposable so I'm not sure if there's anything to be done or not, but we do have errors and issues (like the GetOrdinal problem) which seem to be load-related, and I'm wondering if this is part of the problem.
I'm creating my Data Access Layer and I want to return my object but not all the fields so this is the code i'm using
CODE:
I then call this method in the Business Logic Layer
CODE:
lastly I try to call in in my user interface and bind it to a DataGridView
CODE:
But I keep getting this error: Unable to cast object of type 'System.Data.Linq.DataQuery`1[VB$AnonymousType_0`3[System.String,System.String,System.String]]' to type 'System.Collections.Generic.IEnumerable`1[PP_DAL.DCProposal]'.
I would like to build a base class for my SQL Data Access Layer. I have most of it based out, but have a question about how to handle errors within the base class. I have a method for ExecuteNonQuery, ExecuteReader, ect...
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I'm looking into adding some unit tests for some classes in my data access layer and I'm looking at an update routine that has no return value.It simply updates a row based on the id you provide at whichever column name you provide.Inside of this method, we collect the parameters and pass them to a helper routine which calls the stored procedure to update the table.Is there a recommended approach for how to do unit testing in such a scenario?
View 4 Repliesusing an object-binding I have a an object representing "Employee". The employee has an ID-property. The ID of the employee must be unique.
My validation of the entered data is handled in the property set part of the object. In general, I validate criteria belonging to the object to validate only (eg numeric range of the ID, if it's value is not empy, ...). But in this case I need to know all ID's from the other employees. My tried this:
''' <summary>
''' Set EmployeeID
''' </summary>
[Code].....
I am working in VB.NET defining my own classes. I have 5 classes, Policy, Coverage, CoverageCollection, Layer, and LayerCollection. Policy has a bunch of data items, one of which is of type CoverageCollection. Coverage has a bunch of data items, one of which is of type LayerCollection.
Policy
private id as Long
private name as String[code].....
Then I do like "dim p as Policy". So, iIn order to get to properties on a Layer, I reference it like p.cov(0).lyr(0).face. What I am trying to do is add a readonly property to Layer that is calculated using some Layer information but also using something from Coverage (or even Policy). I can take this in as a parameter to the property, but I think there should be a way to get at Coverage/Policy information since I am "under" it already. Is there a way to do this?
I am wanting to develop a VB program that will access a web page containg XML format data and pick out one number.I have opened the web page and see the number between tags <*> <*> how do I point my search to the web address, I have found XML examples of data being searched when the file is on your hard drive, how to point my program to a http:// web address and then how do I scan or search for my number?
View 1 RepliesI have an Access database file, which the application needs to connect only when it needs to run a query. The database has five fields. The first two fields contain numerical values (double). The rest are text values.
Well, I don't have trouble accessing the database file. In fact, I don't have trouble running a query on those three fields containing text values, either. But I have trouble making a query on numerical fields. If I run the following, the application will exhibit a data mismatch error.
'MyConnection As OleDbConnection
'MyAdapter1 As OleDb.OleDbDataAdapter
'nIP is a large number like 3647665152
[Code].....
I am using ms-access 2002. I have to export the data of a ms-access table in Fixed Width format. To accomplish this I am using DoCmd.TransferText method.
DoCmd.TransferText acExportFixed, "schema.ini", "table_ABC", "C: estingTestData.txt"
But I am getting error message: "Run time error-3625 The text file specification 'schema.ini' does not exist.You cannot import, export, or link using the specification."
Here schema.ini is at same location as of text file. i.e. "C: esting"
I tried with
DoCmd.TransferText acExportFixed, "C: estingschema.ini", "table_ABC", C: estingTestData.txt"
but no success.
For delimited format it is working fine
DoCmd.TransferText acExportDelim, "", "VDMMEMBS", "C: estingTestData.txt"
I have gone through the link [URL]
Error message is same as of me but example shown is related to import of txt file.
i Have Used Database file for storing Data in my Application.Now I want to take backup of data in Access, Excel or in Any other Format.
View 1 RepliesI am using String.Format("{0:C2}", -1234)to format numbers.is always formats the amount to a positive number, while I want it to become $*-*1234
View 4 RepliesI've never used a List(Of) before and I'm not sure how to pass it to the Data Layer of my application. The ColResCategory is a property within the Business Layer (See below) and it needs to be passed to the Data Layer. ReplaceResCategory (See 2nd Code view) is another class file within my Business Layer and the ColResCategory references it.
Public Property ColResCategory() As List(Of ReplaceResCategory)
Get
If IsNothing(mColResCategory) Then
mColResCategory = New List(Of ReplaceResCategory)
End If
Return mColResCategory
[Code] .....
I'm creating a Data Layer for a Web Application and in one of my functions, I need to pass in a Structure full of Customer info. This Data Layer is essentially a DLL. My problem is that I'm not sure how to do this.Below is my code and what I want to do.
[Code]...
Need a SQL Server "SQLClient" (VB) Data Layer Class?
View 2 RepliesWe have data that's updated nightly in a database residing in the same instance as my app's database. So to save on database calls, I want to cache this static-for-the-day data into a List(Of MyObject). From a theory point of view, should this cached List(Of ) be cached in the presentation layer code, via a global variable? Should it be in a global variable in the .DLL?I'm thinking in the .DLL, because I created a service layer, which is exposed publicly to the GUI and makes calls to the data access layer inside the .DLL:
Public Shared Function Search(ByVal criteria As Core.Other.Customer) As List(Of Core.Other.Customer)
' TODO: Check the customer cache to see if it has been populated yet. If not, populate it.
If 1 = 1 Then
[code]....
If you want to go to [url]... there is a tutorial about Luna, a vb.net code generator for data Layer of application
View 6 RepliesI am a fairly rookie programmer who is trying to learn the basics of n-layered architecture (DAL, BLL, UI). The application I am programming is a single tier, 3-layer application written in VB.NET (.Net 3.5). Layers as follows:
DAL
BLL
UI
COMMON - contains DTO's right now.
I am having trouble determining what to pass between my BLL and UI. My instinct tells me that I should only pass data to the UI, and not the full business object from the BLL. Consider two scenarios:
1) Pass the BO directly from BLL to UI. This exposes BO methods and allows the UI direct access to the BO, which seems bad.
2) Pass only the pertinent data from the BO to the UI. For instance, a customer has a Name and Address. This data is really what we want to show/edit in the UI, so we would only return that data to the UI instead of the full BO. The UI would then call to the BLL to update a specific BO.
I am inclined to use #2, but I don't know the best way to implement it. The way I have it programmed now, if I only return data from the BLL, all references to my BO's will be lost and the GC will claim them. Based on this, I have some questions:
1) Should I keep business objects alive between calls to the BLL? The alternative is to re-create them every time I pass data through the BLL, which seems wrong.
2) What is the best way to keep a BO alive in a single tier architecture (how to hold a reference if we dont pass it to the UI?)
3) How do n-tier applications do this? Do they keep the BO's alive in the BLL and wait for an update from the UI? Doesn't this require a lot of "book keeping" in the BLL to make sure BO's are released when they are no longer needed?