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How about clearing the fields/variables after insertion? Then before inserting you validate that data to make sure it exists.
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I invested some time investigating this and the only solution I found working is based on some interaction between client data (ViewState, ...) and server data (Session, ...). Why:
- I don't accept solutions like "Check if the record already exists in the database" etc., because this is limited to inserting data to database, useless for any other scenario. Plus it has other flaws.
- You can't rely solely on client data (by this I mean data received from the client, like ViewState, POST data etc.), because when the user hits F5, the same request with the exact same data is sent to the server - if you accept the request as genuine the first time (and insert some data to the database), there is no way to dismiss it the second time (after refresh) because the data is exactly the same, so any deterministic algorithm for refresh detection can't possibly work. Half the people in the posts above don't realize this.
- I don't accept page redirections, because they either don't work (see above, try yourself if you don't believe) or if you try hard and make them work, they destroy the page state so it may be difficult to keep track of where the user was in the application, etc.
This eliminates all the solutions from the above posts. Like I said, the only way I got to work was to maintain a state-interaction between some Session variable (or any server piece of data) and ViewState variable (or any client piece of data). During normal requests, you keep these in sync and when you receive some Insert request, you compare them and check if they are in sync. If they are, the request is genuine and you can perform the insert. If the user hits Refresh (F5), the ViewState data is old compared to the server data and you recognize the request as refresh and do not perform the insert.
I event made a small component for this purpose, which you simply add to the page and then call BlahBlah.IsRefresh whenever you need. I can publish it somewhere if anyone cares. I think Microsoft should have long ago addded this functionality to the Framework so we could call Page.IsRefresh just like Page.IsPostback.modified on Wednesday, February 17, 2010 3:56 AM
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I am developing a mail application. Through smtp I am sending mail.
I work properly. Mail will send successfully.
After sending mail I am display message your mail has send successfully(which is show after the mail has been send).
But the problem is that when I press F5 button then mail again send.
And it is sending again and again when ever I press F5
I donot want to send mail again when pressing F5 and message will also will display after mail has been send.
I tray to redirect the page it solve my problem to resend the page but in this situation massage will not display.
Plz can u help me
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Im having around 30 Checkboxes in page i need to insert name of those checkboxes in a single column(seperated by comma) of table into db and also need to bind them from db
how can i do it in simple way....
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| I dont think there is simple way except making a temp collection after getting data from db and again costomise the names according to your requirement. Cheers!!
Brij
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I think you can use a CheckBoxList for this. Just get the items from the database, split it on "," and get a array/collection and bind it in..
BTW, why would you want to save the names of checkboxes to the db?? It should be a pre-defined list editable through the DB or other means only.
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in CS page split it with ',' and using for loop bind the each checkbox. now when you want to save in DB again using loop, save in one string (comma separated)(both Id and Text), pass this string to DB and using while loop split it with comman and update the text with particular Id.
let me know if you have any issues.Regards
Keyur Satyadev
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Hi All,
I am deploying my website by using add webdeployment project.
But in my website i have used the WebUserControls in my website. The WebUserControls events are handled in form[which contains WebUserControl] through Delegates & Event Handlers.
These events of WebUserControl have been initialized at form Default.aspx Page Init event.
When i build the Project it gives no errors, the site runs perfectly...
But when build the Deployment project i got a compilation errors of WebUserControl events where i initilized at form Default.aspx page init event.
Its giving error message like 'MyUserControlUC' could not found are u missing add reference.
For sample:
==========
MyUserControlUC.ascx
<pre>
<scrpt runat="server">
//delegate
public delegate void DropDownSelectedIndexChanged(object sender, EventsArgs e);
//event
public event DropDownSelectedIndexChanged IndexChanged;
//call the event
protected void ddl_items_SelectedIndex_Changed(object sender, EventsArgs e)
{
if(IndexChanged != null)
IndexChanged(sender,e);
}
| <asp:dropdownlist id="ddl_items" runat="server" autopostback="true" onselectedindexchanged="ddl_items_SelectedIndex_Changed">
|
Default.aspx
<%@ Register TagPrefix="uc1" TagName="SampleUserControl" Src="~/MyUserControlUC.ascx" %>
<html>
<head></head>
<body>
<form runat="server">
<uc1:SampleUserControl BackColor="Gray" id="SampleUserControl1" runat="server"></uc1:SampleUserControl>
</form>
</body>
</html>
Default.aspx.cs
<pre> protected override void OnInit(EventArgs e)
{
base.OnInit(e);
InitializeComponent();
}
private void InitializeComponent()
{
this.Load += new EventHandler(this.Page_Load);
SampleUserControl1.IndexChanged += new ASP.MyUserControlUC.SelectedIndexChanged(ddl_items_SelectedIndexChanged);//Here i am getting error while building deployment project.
}
private void ddl_items_SelectionIndexChanged(Object sender, EventArgs e)
{
//Code here to handle ...
}
Thanks & Regardsmodified on Tuesday, February 16, 2010 8:06 AM
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If you are having the UCs in different project from the main web site, then check if the Build order of the solution is set correctly and check if you have enabled compiling the primary assembly and all it dependencies.
HTH!
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Hi Dinesh,
Thanks for ur reply.
But the WebUserControl are in sample project.i.e, in main website it self
Regards,
kv sekhar
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mm, try qualifying the UC with it relative path like so -
<%@ Register TagPrefix="uc1" TagName="SampleUserControl" Src="~/MyUserControlUC.ascx" %><br />
This denotes taht "MyUserControlUC" is available in the application root folder.
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Hi Dinesh,
<%@ Register TagPrefix="uc1" TagName="SampleUserControl" Src="~/MyUserControlUC.ascx" %>
is right, in the post i wrote wrong. In register tag no error.
Problem with at Initilization of UserControl events in form.
any suggestions is appreciated..
Thanks & regards,
kv sekhar
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Can you post the exact compilation message and the reference line number?
Well, I can't think of whats going wrong. Hard luck.modified on Tuesday, February 16, 2010 5:21 AM
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Hi Dinesh,
Sorry for late response...
The exact error message is
1.System.Web.UI.UserControl does not contain a definition for 'IndexChanged' and no extension method 'IndexChanged' accepting a first arguement of type 'System.Web.UI.UserControl' could be found.(are u missing a using directive or an assembly reference)
2.The type or namespace name 'MyUserControlUC' doesn't exist in the namespace 'ASP' (are u missing an assembly reference?)
This error i got at Default.aspx.cs page
private void InitializeComponent()<br />
{<br />
this.Load += new EventHandler(this.Page_Load); <br />
SampleUserControl1.IndexChanged += new ASP.MyUserControlUC.SelectedIndexChanged(ddl_items_SelectedIndexChanged);
}
regards,
kv sekhar
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From the first post, your IndexChanged event is of type (Delegate) DropDownSelectedIndexChanged. Where as you are trying to assign it to a delegate of type MyUserControlUC.SelectedIndexChanged. You should actually be assigning it to MyUserControlUC.DropDownSelectedIndexChanged.That is what the error message implies too.
You have used the namespace qualifier "ASP" to assign the IndexChanged event handler. Is this namespace correct??
Try the changes, it might do the trick.
HTH
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Hi Dinesh,
Thanks for your response.
That was not a problem, because the application is running perfectly and the dropdown event fires and giving the results to me.
No errors while building and running the WebSite.
But there are bulid errors while building the DeploymentProject of above website.
The errors i already posted in my above post.
Thanks & Regards
kv sekhar
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Could u provide the information details whats the error or at the root itself can u specify it clealy
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Hi Nath,
Sorry for late response...
The exact error message is
1.System.Web.UI.UserControl does not contain a definition for 'IndexChanged' and no extension method 'IndexChanged' accepting a first arguement of type 'System.Web.UI.UserControl' could be found.(are u missing a using directive or an assembly reference)
2.The type or namespace name 'MyUserControlUC' doesn't exist in the namespace 'ASP' (are u missing an assembly reference?)
This error i got at Default.aspx.cs page
private void InitializeComponent()<br />
{<br />
this.Load += new EventHandler(this.Page_Load); <br />
SampleUserControl1.IndexChanged += new ASP.MyUserControlUC.SelectedIndexChanged(ddl_items_SelectedIndexChanged);
}
regards,
kv sekhar
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I am developing a mail application. Through smtp I am sending mail.
I work properly. Mail will send successfully.
After sending mail I am display message your mail has send successfully(which is show after the mail has been send).
But the problem is that when I press F5 button then mail again send.
And it is sending again and again when ever I press F5
I donot want to send mail again when pressing F5 and message will also will display after mail has been send.
I tray to redirect the page it solve my problem to resend the page but in this situation massage will not display.
Plz can u help me
|
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|
Hi,
I have a file in other computer say (\\10.10.10.10\\sharedFolder\abc.txt) and asp.net is running on local computer
Can I use Response.WriteFile to server this file when client requested.
Response.WriteFile("\\10.10.10.10\\sharedFolder\abc.txt");
But I am getting an exception saying file does not exists at location :
c:\\inetpub\\wwwroot\\10.10.10.10\\sharedFolder\abc.txt
Please let me know how we can do this.
Thanks,
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It is not a good practice to access the file system except your application root from a web application. If you should then you need to use a user credential with a elevated access rights than the default IIS user. Server admins won't let you do that.
BTW, Response.WriteFile does not read a file, it writes the response to the file on the current execution directory. To really write into a file you need to use File objects.
Do you want to write data into the file or read the file and display the data to your users on your application?
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Try using following if the file is on the same server
Response.WriteFile("~\\sharedFolder\abc.txt");
Or use following if the file is not on the same server
Response.WriteFile(@"http://10.10.10.10/sharedFolder/abc.txt");
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Hi,
I am developing small web application(ASP.NET and MySQL)with CURD Operations which has one table and has 30 columns.
my ques:
Suppose If more than one person tries to modifies the same row(record) then it should throw message as "Someone already editing the record".
I find out optimistic and pessimistic locking for the above problem.
How to achieve this one and which method to use any sample application which will be very useful
Reg,
Subbu
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use ado.net transaction for that so that allow only one person at time to update record
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i had that Problem once in my early days. but look at how i wrote the SP to overcome that. I check if the Value has change since i have retrieved the data, if it has change i dont Update. look at this
Coding an N-Tier Application in C# Without Any Wizard: Part II[^]Vuyiswa Maseko,
Spoted in Daniweb-- Sorry to rant. I hate websites. They are just wierd. They don't behave like normal code.
C#/VB.NET/ASP.NET/SQL7/2000/2005/2008
http://www.vuyiswamaseko.com
vuyiswa@its.co.za
http://www.itsabacus.co.za/itsabacus/
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