A quick question on caching dataset objects. How can I know if the data is changed in Sql when caching data? I don't want to specify time constraints but used a strategy where data is changed in sql and I have to refresh my cache?
View 1 Replies
I want to track changes in an application. So I've made a copy of the main table in that application, and am accessing both tables in the application using two separate datasets.
My plan was to use the HasChanges method of the main DataSet to get changed rows and then insert those into the copy table. When I run the code I get an error:
A first chance exception of type 'System.InvalidCastException' occurred in MyApp.exe
Unable to cast object of type 'MainDataTable' to type 'MainAuditDataTable'.
Here's the code:
If Me.DataSet3.HasChanges Then
' 'look for each row that has changes, not new rows
' 'insert that row into the auditing table
[Code].....
on my Form I have a DataViewGrid and some textboxes with a save button (they are filled with additional data of the selected row).Save is disabled first, when I change something in the textboxes the save button is enabled.When the user changes a gow in the grid, I want to ask before changing the grid row, if he wants to save (if the button is enabled).I am using RowEnter but this is too late, then the selected row already changed (and my textboxes already got new data)...What event can I use to ask if I should save stuff before the user changes a row?Something like BeforeRowChanging with a chance to cancel changing the row?
View 2 RepliesI'm pulling data from a Lotus Notes database, this works fine but when I change the data and pull it again, it doesn't take the changes, a restart solves this so it must be getting cached somewhere, how do I prevent it?[code]...
View 7 RepliesIs it possible to cache dataset which is accessible globally.Example: One windows service creates a dataset and caches it.Another Web Application and Windows application references that cache and populates in datagrid.
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]....
I'm using interop.msxml2.dll to open XML and txt files off an Internet server. The response that is received from the server is stored in my application's variables. I've recently noticed that the application doesn't always update the information when it goes to download a file that it has already downloaded in the past. For example, if it downloaded a file off the server when it started up, then when it attempted to download the new, changed file 5 minutes later, it would still return the same value as the first one. Even after closing the application, it would still return the incorrect, older value. How to stop this "caching" of data, and only allow the program to download the latest file off the server.
View 1 Replies- I'm working on a windows forms application (.NET 4.0). - My form contains a 'Fast Line' chart using the Microsoft chart control included in VS2010. - The chart gets filled with about 20,000 datapoints. - My application then starts receiving market data from a server via DDE (Dynamic Data Exchange) in real-time and adds it the chart.
Note: I have no control over the server and so I have to deal with DDE only even though it's an outdated technology. VS doesn't support DDE anymore and so I use the Ndde library which works like a charm.
Private Sub StartDDE()
'first we connect to the DDE server:
Dim client As DdeClient = New DdeClient("ServerApplication", "Bid")
[Code].....
I'm trying to have a Message Box be displayed when the user either closes the form, or changes the tab. The Message Box should only be displayed if the data in a dataset has been edited/changed, but hasn't yet been changed.
View 2 RepliesMy Scenario is that i have fetch data from one SQL Server table into vb.net DataTable.Now if any record is changed or New Record is saved into SQL Server Table i want to fetch or update only that record into my data table. is it possible.
View 1 RepliesI am having issues understanding why it is that a text box that has been bound to a dataset correctly updates that dataset when the text in the box is manually changed i.e. by changing it using the keyboard but the dataset does not recognise the change when I change it in code.Am I missing something obvious? The text is changed in code when the user clicks on a command button that copies the text from another textbox on the form to this textbox.
[Code]...
As i mentioned, manually it works fine but when I use the comman button to change the text it does not recognise that any changes have occured.
What are the various objects in Dataset ?...
View 2 RepliesI sometimes come across patterns or common practices that I do not agree with. I have a clear opinon of what is considered "good design", which is mainly based on my understanding of abstraction and creating layers.IMO, the core of an application is it's object model. It's a hierarchic model where one object references other objects or lists of them. That's a memory-internal model. For example, a house object references a list of rooms referencing lists of furniture.An object is identified by it's reference. There are no IDs or PKs in that layer.Saving/Loading data is an additional feature. Sure, no application will do without, but it's based on top of the core of the application. I could write an application that works very well without loading/saving, and for version 2 I will think about whether to save data to a database or an XML file. Merely this fact proves that a database layer is not the lowest. I've never agreed with that three-tier model - even if you call me unteachable.
In addition to all application objects, there are Datasets - and that's my problem now. They can be considered as a copy of what is already present in the application's object model. Its from a different, table-oriented view. As both structures exist in parallel, there's the need to synchronize the DataSet with the (rest of the) application's objects.That's the task that I am always struggling with, and I ask how you handle it. I know this is a major design question but, fortunatelly, I could quite get around this problem so far.The only solution I can imagine is maintaining additional relation lists. For example, whenever the property of a room object changes, that change must be reflected in the associated DataRow in the DataSet. For this purpose, I need a look-up table that tells me the PK of the given room in the database. It requires a lot of additional efforst to do all the synchronization.Again, the house or room object itself does not have a PK and it won't get one because on that layer, it doesn't even know that a database exists.
I want to define a function similar to:[code]My current definition is having an issue with the following statement:GetList = (From x In oDS.Tables(0) Select New T(x)).ToList.I can't figure out how to get to create a New object of type T, any suggestions?
View 2 Replieshave a lot of experience with LINQ, but should your verb be attached to the array?
data.Tables("people").LoadDataRow(parsed(int1, 1), True) S/B
data.Tables("people").LoadDataRow(person.parsed(in t1, 1), True)
I am using VB Exopress 2008 and SQl Server Express 2008 in Windows Vista Home Premium. I have created a dataset after importing all tables and queries from MS Access to SQL Server. I have now added a view in SQL Server that I want to access and use in VB Express. However on clicking "Refresh" for the dataset the new view does not display in the available objects, only those I originally imported and opened with the original dataset. What, pleas am I doing wrong? How can I see this new View?
View 3 RepliesI use datasets to hold rows of vendor data and case data and such.
I would like to be able to regularly refresh the rows in these datasets that have been changed by other users touching this same database.
In the app we update like this:
_adapter.Update(_casetable)
That looks through the dataset for rows I've changed and calls the UPDATE sprocs.
Let's say I know that case # 12345 has been changed. How would I cause a refresh of the dataset for that case - getting new data from the DB?
I have tried everything I can to get beyond this error which shows below as <<<<< error here. It is trying to fill a dataset from a data adapter. If I change the SELECT statement to just SELECT * FROM xTable I get the correct number of records in each table. But anytime I try with a more complex statement I get the error message shown below which indicates System.Data.Common.DbDataAdapter.Fill(DataSet dataSet. I've completely erased all data and entered a new set of test data so I know there is no problem with relationships. Each table has primary key which is foreign key in other table. IS there something wrong with the Imports section: Imports System
[Code]...
i am trying to copy data from a standard Dataset to a Type Dataset (XSD) of same table structure. i want to use Automapper to do that one. So how can i do that using automapper?
View 1 RepliesI have two Datagrids, One grid has all the customers garments on it with style number and contact length. The other grid has the users who have garment issued to them. the style number is in both grids. I need to loop through the users grid and say if the contract number is 1 from the first grid then the contract date on the second grid will be todays date + 365 days (year contract) I have looked at using a stored procedure and also a for each command but I am just getting stuck with it all. [Code]
View 1 RepliesI changed my Username on my computer from i.e. "xxxxxx x xxxxx" to "Dennis"
VB 2008 during a compile gave me the following error: Error reading icon 'C:Usersxxxxxx x xxxxxAppDataRoamingMicrosoftVBExpress9.0VSProjectApplication.ico' -- The system cannot find the path specified.
The file "VSProjectApplication.ico" is in 'C:UsersDennisAppDataRoamingMicrosoftVBExpress9.0'
Somewhere in the VB2008 "configuration" files I believe that I need to manually change the old path to the new path.
I found the old path in the ".suo" file. The ".suo" file is not a text file. How can I edit the .suo file, save it so that it will work?
Ok, I have been going around and around with this for hours (Searching, etc). This is what I want to do, I want to load data into a Text Box and if the user changes the text in the Text Box I want to be able to save the new text.
My problem in the TxtBox_TextChanged event the data contained in the txtNarrative Text box is the new data that the user typed in (<>ABCD) but in the btnSubmit_Click event the data contained in txtNarrative is the original value ABCD.
<%@ Page Language="vb" AutoEventWireup="false" CodeBehind="Default.aspx.vb" Inherits="WorkBench_VBNet._Default" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
[Code]....
On my form with my detailed layout of my database in textboxes i can change my data or add new record.
how can i verify if there was any changes to a record when the form is being closed or when my cancel button is pressed.
i want to create a message box that warns tha there hav been changes made should it be saved yes or no
'm developing multi user systems where for example I could have a form with a list of users on it. If a user on another system adds a user then I would ideally like for the new user to show up on my list reasonably soon. While that could be done by getting refreshing the list every couple of seconds I would prefer to be able to identify that a change has happened and then be able to decide what to do from there (whether that be actually refresh the list or inform the user that a change has happened and ask them what to do).
The only way that I can think of doing this is to store the information that was originally retrieved and then every x number of seconds requery the database and then compare the two sets of data, if there are differences then raise an event.
I have a form that builds and populates dynamic text boxes from parsing a file. There is a "Last Name" text box that when populated, also labels a tab page with the name. After the form is populated, the user can change data as they desire but I was wondering how to update the tab page text when the user updates the last name text box? All the controls are built in code.
View 5 RepliesI am retrieving data from my database using a TableAdapter. I was wondering if there is some way I can tell (or be informed) that the data has changed and I therefore need to do another Fill? That way I can just Fill on demand rather than every time the user requests to see the information and I am forced to do a Fill before showing the data because I don't know if is current or not. For the record I am using an ODBC connection string to access a Pervasive PSQL database
EDIT I was thinking I could check the last write time of the MKD file to check if this has changed but this doesn't seem to be reliable as it is not written to until the connection is closed. Does anyone know the circumstances when this is written?
Im using VB.NET 2008
I know I can exit a program by using the End statement.
But i was wanting to know how to check to see if the data has been changed since it was loaded and bring up a diaglog box up saying the data has been changed or not saved, would you like to save the data before exiting?
I will have a form that will have a yes, no, and cancel buttons.
Im using VB.NET 2008 I know I can exit a program by using the End statement.But i was wanting to know how to check to see if the data has been changed since it was loaded and bring up a diaglog box up saying the data has been changed or not saved, would you like to save the data before exiting?
I will have a form that will have a yes, no, and cancel buttons.
I am trying to get my grid to refresh automatically when the underlying data is updated in the database. Isn't this supposed to work? Or am I missing something? I created a DataTable within my DataSet. Then I created a new form and added a DataGridView (actually I'm using DevExpress' XtraGrid but am trying to get it to work with just the Microsoft controls). I use the menu in the upper left of the grid to set the grid datasource to the datatable in the project data source. This then automatically adds the dataset, BindingSource, and TableAdapter to the form.
[Code]...
I have been trying to do this for ages and having no joy whatsoever.
I have a ribbon window of the following hierarchy:
MainWindow
MainContent (Tab Control)
TabContainerViewModel
ViewModelBase
View model base has an ObservableCollection of tabs type ViewModelBase. The Tab Control itself is binding fine to these, displaying appropriate view models. I have 2 problems however, I want a "NotepadView" (Of type viewmodelbase) to be replicated numerous times (one view many view models).
At the minute, I have 4 views (NotePadViewModelx where x is 1-4) with corresponding viewmodels, this is because each view had the same text per tab. Now I have individual views per tab.
When I type into tab 1 and switch to tab 2, I lose what I typed in tab one when I click back.
