Fransiscus Setiawan

Technical articles on AI agents, Azure, .NET, architecture, and EV charging systems from Sydney.

Author: fransiscuss Page 19 of 20

Only one instance of script manager can be added to the page

By

On August 29, 2008

In ASP.NET, C#, VB.NET

I’ve got this error when i have ajax toolkit script manager on the master page while at the same time i’ve script manager on the content page. This is the primary cause of this error.

The work around this is to move the script manager which is located on the master page before the content place holder or if you have any user control which uses script manager as well, place before it. It should be placed on the top of anything which uses this control and the most important thing you need to change the script manager in the content page or user control to be script manager proxy

App_GlobalResources maps to a directory outside this application, which is not supported

By

On August 29, 2008

In .NET & C#

I got this error when i switched the default web server in visual studio to use IIS instead of visual studio integrated web server. To fix this error is by changing the IIS Default Web Site Properties in (Home Directory -> Local Path). Remove any “\” character at the end of the directory. IIS will automatically add one which causing double “//” at then end and it causes problem if you manually add one before. You can check Default Web Site Properties -> ASP.NET -> File Location for actual setting information

407 Proxy authentication required

By

On August 29, 2008

In .NET & C#, ASP.NET, VB.NET

I found this problem when i try to do any of httpweb request behind proxy and i got error of “407 proxy authentication required”. Normally your company has its own proxy server and sometimes you want to call webservice or reading XML from any website or sending xml to payment gateway.

The workaround this is to use proxy properties of your httpwebrequest variable. this is some snippet

         Dim objRequest As HttpWebRequest
         objSendXML = New XmlDocument
         objRequest = WebRequest.Create(strPaymentURL)
         objRequest.Method = "POST"
         objRequest.ContentLength = strSend.Length
         objRequest.ContentType = "text/xml"

        'for development only!!! have to be blocked on production
         objRequest.Proxy = New System.Net.WebProxy("http://proxy-syd:8080", True)
         objRequest.Proxy.Credentials = CredentialCache.DefaultCredentials

Now you can call your webservice or reading xml behind the proxy server

not valid Base64 character when doing redirect with query string

By

On August 29, 2008

In ASP.NET, VB.NET

I was having a problem in my checkout page, the problem that i had was i’ve got this memberID from the checkout page and it’s being passed to another page via query string. This problem doesn’t happen everytime and it happens rarely, this is what i hate the most!!. After spending a couple of hours, i found the problem is in the query string it self.

when you pass something like this in query string

“c+ckDQiiilyW4r7moRA8oQ==”

and it will be automatically converted becoming

“c ckDQiiilyW4r7moRA8oQ==”

and when you try to decrypt it, it will throw the exception of “not valid Base64 character”

“+” when you pass it to url it will be automatically converted to ” “(blank space)

The work around of this problem is

on the target page, you can do some string replace of ” “(blank space) with “+” , and voila it works!!!!

Dim strQuery As String = Request.QueryString("OrderID")
strQuery = strQuery.Replace(" ", "+")

Failed to enable constraints, one or more rows contain values violating non null, unique or foreign-key constraints

By

On August 29, 2008

In C#, SQL Server & Data, VB.NET

I found this error on my project. Well i spent around one hour to figure out this problem. People might think that this is some silly error message.

The error message i got is “Failed to enable constraints, one or more rows contain values violating non null, unique or foreign-key constraints”.

this is caused by my stored procedure which is

SELECT e.eventid,e.event,e.eventdate,i.email,u.username
,u.firstname,u.surname,i.senttime,i.readtime,i.respond
FROM invitefriends i
inner join users u ON i.franchiseeid=u.userid
inner join events e ON i.eventid = e.eventid
WHERE i.franchiseeid is not null
    and ( (@EventID IS NULL) or (e.eventid=@EventID) )
ORDER BY e.eventdate DESC
GO

Since the query is returning multiple rows with the same eventid and the primary key in my datatable is eventid then it caused the error.

There are two workaround to this problem:

  • by using identity from your own table or you can generate it from your query and you need to regenerate your datatable and make sure check the primary key in datatable since it’s not automatically changed for you.
  • You can also relax the constraint by removing the Primary key on the DataTable

    • Cursor Tutorial in SQL Server

    By

    On August 29, 2008

    In SQL Server & Data

    This is the sample of cursor solutions, i will add the explanation a bit later

    CREATE PROCEDURE AutoSumEventMembers
AS
SET NOCOUNT ON;

/*This stored procedure is used to update the number of players played on the particular event*/
/*Event selected only based on the completed one or the one where the result has been uploaded*/

/*Declare the variable  that is used to store the value coming from cursor*/
DECLARE @EventID int
DECLARE @TotalResult int

/*Declare the cursor for that particular select statement*/
/*You can fetch more that one column into cursor*/
/*You need to make sure that you have the same number of variables when you start fetching it*/
/*Make sure the variable has the same type as the column as well*/
DECLARE Cur_Events CURSOR
FOR
SELECT
EventID
FROM
Events
WHERE
Finalised = 1

/*Open the cursor*/
OPEN  Cur_Events

/*Start fetching from the cursor and dump it into the variable*/
FETCH     Cur_Events
INTO     @EventID

/*Iterating through the cursor until the end of the cursor*/
WHILE @@Fetch_Status = 0
BEGIN
SET @TotalResult = 0

/*Count how many results have been uploaded for particular event*/
SELECT @TotalResult = COUNT(*) FROM EventResults WHERE EventID = @EventID

/*Update the record*/
UPDATE Events SET NumberOfResults = @TotalResult WHERE EventID = @EventID

/*Fetch the next cursor*/
FETCH     Cur_Events
INTO     @EventID
END

/* Clean up - deallocate and close the cursors.*/
CLOSE     Cur_Events
DEALLOCATE Cur_Events

    Controlling PDF document through parameter

    By

    On August 29, 2008

    In .NET & C#

    It’s a simple thing but might be essential. Sometimes you would like to have a link to your pdf document into a particular page. This is how you can do it. Add “page=” and the page no. This is the example

    http://www.adobe.com/prodlist.pdf#page=3

    For the full documentation about controlling the page size, you can download it from Adobe directly by clicking here

    Querystring in Javascript

    By

    On August 29, 2008

    In JavaScript

    This is a function to capture querystring in javascript. I used this javascript to control my menu dynamically.

    
function getQueryString(strParamName){
var strReturn = "";
var strHref = window.location.href;
if ( strHref.indexOf("?") > -1 ){
var strQueryString = strHref.substr(strHref.indexOf("?")).toLowerCase();
var aQueryString = strQueryString.split("&");
for ( var iParam = 0; iParam < aQueryString.length; iParam++ ){
if (
aQueryString[iParam].indexOf(strParamName.toLowerCase() + "=") > -1 ){
var aParam = aQueryString[iParam].split("=");
strReturn = aParam[1];
break;
}
}
}
return unescape(strReturn);
}

    Register Javascript to hide Div

    By

    On August 29, 2008

    In C#, JavaScript

    Sometimes people add javascript into the aspx page instead of using code behind but there is a case when we need to add javascript in the runtime using code behind. This is the example where javascript is used to provide switching of visibility based on the table visibility status. I used this technique to hide another user control when user click expand button. Client ID is required to know the real ID of the user control after rendering. In here we also add onclick event to the image tag.

    if (!this.Page.IsStartupScriptRegistered("tableScript"))
{
string script = @"function checkVisibility() "
+ @"{"
+ @"    var element = document.getElementById('" + this.OuterTableDetailSearch.ClientID + @"');"
+ @"    var elementBtn = document.getElementById('" + this.btnExp.ClientID + @"');"
+ @"    if (element.style['visibility'] == 'hidden')"
+ @"{"
+ @"element.style['visibility'] = 'visible';"
+ @"elementBtn.src = '/Images/button_expand.gif';"
+ @"}"
+ @"else"
+ @"{"
+ @"element.style['visibility'] = 'hidden';"
+ @"elementBtn.src = '/Images/image_casestudy_search.gif';"
+ @"}"
+ @"}";

this.Page.RegisterStartupScript("tableScript", script);
}

btnExp.Attributes.Add("OnClick",
               "javascript:checkVisibility()");

    Row filter in Dataset

    By

    On August 29, 2008

    In C#

    Here it will be useful for someone who would like to filter a particular record in datagrid. You need to create a dataview and filter it. Here, i would like to filter a particular record where the field name is “metakey” and i don’t want to show it when its value is “thumbnail”. So a record where metakey is thumbnail will not be shown at all. It’s a simple thing but it will be useful.

    DataSet metaData = new DataSet();
dv = new DataView(metaData.Tables[0]);

gridMeta.DataSource = dv;
gridMeta.DataBind();

dv.RowFilter = ("metakey  'thumbnail'");
//bind it to datagrid

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