Sunday, 16 January 2005
SQL - change object owner for multiple objects
Tibor Karaszi showed how to do this time saving technique on a newsgroup post. You can use the sp_changeobjectowner
stored procedure in the Master database to change the owner of an
object one at a time, but there is a semi-automatic way to do it.
Open query analyser, change the selected database to the on you want
to work on. The following query generates a list of exec commands for
all the sprocs and UDFs in the database:
SELECT 'EXEC sp_changeobjectowner ''dbo.' + ROUTINE_NAME + ''', ''thenewuser'''
WHERE ROUTINE_SCHEMA = 'dbo'
Execute it, then click the top left corner of the output window, to
select all the rows. Copy and paste the rows into a new query window
To change table owners, modify the query and repeat the proces:
SELECT 'EXEC sp_changeobjectowner ''dbo.' + TABLE_NAME + ''', ''thenewuser'''
Sunday, 16 January 2005 18:37:40 (GMT Standard Time, UTC+00:00) Database
Friday, 17 December 2004
[FIX] aspx validation not working + buttons not clicking
when i deployed my web app to the production server, i found that none of the client-side validation was working.
the first problem was that there was no mime-type set up on the
the .js extension.
the next problem was that the script references in my aspx pages did
not match the script location on the server. the html
source of one of my pages had the webuivalidation.js path set to
but the server directory was "/aspnet_client/system_web/1_1_4322_0/WebUIValidation.js"
so i tried duplicating the directory so that i would have both paths
on the server, but that caused strange problems on the aspx page, such
as buttons not clicking (when the event handlers are definitely
so what i did was run aspnet_regiis -i on the server to make sure
all the script maps are registered properly, and it worked.
if you don't have control over the web server, you can add the following to your web.config
<webControls clientScriptsLocation="/aspnet_client/system_web/1_1_4322_0/" />
Friday, 17 December 2004 12:46:46 (GMT Standard Time, UTC+00:00) Asp.Net
Wednesday, 15 December 2004
Can't debug web projects with VS 2003 after installing VS 2005
Can't debug web projects with VS 2003 after installing VS 2005
Fortunately Fahad Khalil found the answer to this, he posted this simple solution on his blog.
I am reproducing it here for my own records. Shoot your IIS Console, then click on the Default Website and click on Properties. You will see a Brand new shiny tab [labelled ASP.NET] ... courtesy VS .NET 2005 :). Select the correct version i.e. 1.xx :)
Cheers Fahad. Saved me a lot of work.
Wednesday, 15 December 2004 10:58:09 (GMT Standard Time, UTC+00:00) Asp.Net
Sunday, 05 December 2004
An intelligent 404 page, suggest pages with a similar name to the requested page
Did you ever notice on big sites like microsoft.com, if you reach a
page that doesn't exist, they don't just say "Sorry, 404.", they give
you a list of pages that are similar to the one you requested.
This is obviously very nice for your users to have, and it's easy
enough to integrate into your site. This article provides source
code and explains the algorithm to accomplish this feature. Note: the
real benefit of the approach outlined here is the semi-intelligent
The need for this grew out of a client of mine who was changing
content management system, and every url in the site changed, so all
the search engine results came up with 404 pages. this was obviously a
big inconvenience, so i put this together to help users find their way
through the new site when arriving from a search engine.
See it in action
Go to the following page http://www.iserc.ie/December15-ISERCWorkshoponTesting.html (which doesn't exist), and the 404 page should give you a list of pages that have quite similar names.
- Your web site must be set up so that 404 pages get redirected to a .net aspx page
- You must have some way of getting an array of all the page
urls in your site that you want to compare 404 requests against. if you
have a content management system, there is probably a structure of all
something), or you could write your own query to get the pages from a
database. if don't use a content management system, you could hard-code
a string array variable in the 404 page code behind containing the page
names, or think up some way of dynamically reading all the .aspx or
.html pages from the file system.
- When the 404 page is accessed, you need to know which page was
requested. Using web.config, you can set up 404 errorCodes to go to
/404.aspx, where it will tag on the requested page to the querystring.
the source code here assumes you have this approach, but you can
obviously change it to your own needs, simply change the
Why Regular Expressions are not enough
To compare strings, you can use System.String.IndexOf or you can use
regular expressions to match similarities, but all these methods are
very unforgiving for slight discrepancies in the string. in the example
url above, the page name isDecember15-ISERCWorkshoponTesting.html but
under the new content management system, the url is December 15 - ISERC
Workshop - Software Testing.html, which is different enough to make
traditional string comparison techniques fall down.
So i looked around for a fuzzy string compare routine, and came
across an algorithm written by a guy called Levenshtein. His algorithm
figures out how different 2 strings are, based on how many character
additions, deletions and modifications are necessary to change one
string into the other. This is called the 'edit distance', i.e. how far
you have to go to make 2 strings match. This is very useful because it
takes into account slight differences in spacing, punctuation and
spelling. I found this algorithm on http://www.merriampark.com/ld.htm
where Lasse Johansen kindly ported it to C#. The algorithm is explained
at that site, and it is well worth a read to see how it is done.
Normalising the Scores
I originally had a problem with the algorithm because it gave
surprising results for certain situations. If the 404 page request was
for 'hello' and there is a valid page called 'hello_new_version' and
another valid page called 'abcde', then the 'abcde' page gets a better
score, because fewer changes are needed to make it the same as hello
(just change the 5 characters in 'abcde' into 'hello'). this is 5
changes, even though the 'hello_new_version' is semantically a better
match. Fortunately, a kind newsgroup participant named Patrice
suggested that i divide the score by the length of the comparison
string, to normalise the results. This worked perfectly, and i found
that a score between 0 (perfect match) and 0.6 (a good match) is worth
including as a suggested page. You can change this value in the
ComputeResults() method if you want to make it more or less flexible.
private void Page_Load(object sender, System.EventArgs e)
The above code shows the 4 key tasks that make up this solution. Each method is explained below.
Using the code
- GetRequestedUrl() simply figures out which page was requested. In
this example, it is assumed that your web.config contains the following:
this example, the querystring on the 404.aspx page contains the
requested url. SetUpSiteUrls() is where you load in all the pages in
your site. In my content management system, i have an xml file with all
the names, so i do an XPath query and add in the names one by one to
private void SetUpSiteUrls()
this.validUrls = new ArrayList();
* Insert code here to add the pages in your site to this arraylist
- ComputeResults() iterates through the urls you set up in
SetUpSiteUrlsreturns and attaches a score of how close each one is to
the requested url. It also sorts the results and discards any that are
not a close match.
private void ComputeResults()
ArrayList results = new ArrayList(); // used to store the results
// build up an arraylist of the positive results
foreach(string s in validUrls)
// don't waste time calculating the edit distance of nothing with something
if(s == "") continue;
double distance = Levenshtein.CalcEditDistance(s, this.requestedUrl); // both in lower case
double meanDistancePerLetter = (distance / s.Length); // anything between 0.0 and 0.6 is a good match. the algorithm always returns a value >= 0
if(meanDistancePerLetter <= 0.60D)
// add this result to the list.
results.Add(new DictionaryEntry(meanDistancePerLetter, "<a href='" + s + ".html'>" + s + "</a>")); // use dictionary entries because we want to store the score and the hyperlink.
// can't use sortedlist because they don't allow duplicate keys and we have 2 hyperlinks with the // same edit distance.
IMPORTANT NOTE: One thing to definitely look out for is the inner-most
line of the above code. results.add(new DictionaryEntry(...). I am
adding in a html hyperlink, with the name of the page + ".html". This
may not be a correct link in your web site, because you may have
removed the folder part of the url while populating the validUrls
arraylist. You may need to expand the data structures used in this code
to include full url for each page.
- BindList() simply binds the arraylist of results to the datagrid, which is configured to display them in a bulleted list.
private void BindList()
if(results.Count > 0)
this.lblHeader.Text = "The following pages have similar names to " + this.requestedUrl + "";
this.DataList1.DataSource = results;
this.lblHeader.Text = "Unable to find any pages in this site that have similar names to " + this.requestedUrl + "";
The 'magic' in the code is all done with the
Levenshtein.CalcEditDistance method which returns the distance between
2 strings. It is included in the source.
Winforms Test Application
If you're interested to test out the levenshtein algorithm, i've
written a windows forms application that lets you enter a string (e.g.
a page url) and also a list of strings to compare it against (e.g. all
the page urls in your site), and it gives you the 'edit distance'
scores. download here (7k)
I think this is a great feature because it adds significant value to
the user experience for a web site. Please feel free to comment below
if you have any questions, find any bugs, improvements, or if you can't
get it working, or if you use it in a novel way.
Sunday, 05 December 2004 15:15:28 (GMT Standard Time, UTC+00:00) Asp.Net
Monday, 22 November 2004
How to disable new rows in Windows Forms DataGrid
i found a few work arounds to prevent a datagrid from displaying the
* new row. one of them involved using a dataview as the datasource,
with AllowNew property set to false. however, someone
called Sameers from theAngrycodeR pointed out that a datatable has
a DefaultView property which also has this AllowNew property. so you
can use the following code (if your datasource is a dataset):
this.dataSet1.Tables.DefaultView.AllowNew = false;
and you get to keep the dataset or datatable as the direct datasource.
Monday, 22 November 2004 17:05:24 (GMT Standard Time, UTC+00:00) .Net Windows Forms
Using custom datatypes in a .Net Dataset
In my content management system, i allow the user to define their
own 'objects' (e.g. Staff Member) and then i provide templated
data entry forms to let them populate instances of these objects.
It's aimed at non-techies so i have my own datatypes called 'Text'
which maps to System.String, 'Number' maps
to System.Double etc. I also have a few custom data
types called 'File' and 'Image' to allow the user to add files or
images to an instance of the object.
This business of doing column-mapping was ok as long as my data
types had obvious .Net equivalents, but 'Image' doesn't in my case. i'm
only storing a reference to the image, but in my application, it's not
to be treated just as a System.String. When the user is creating
a new object with an 'Image' field in it, i want to display a file
upload instead of a textbox, and when i go to display the object on the
site, I want to display a html IMG tag with the SRC set to the value of
the image field.
The dataset is serialised into an xml file with the schema embedded.
i needed to find some way of encoding my own custom data type
information into the dataset that would persist into the xml
file. I looked through the VS intellisense and found the
'ExtendedProperties' data column property. This property allows
you to plug in any number of key/value pairs of information to each
column. This was exactly what i needed, so i added in a pair
with something like "MyDataType=Image" for each column. This
persisted nicely into the xml file as follows:
<xs:element name="Photo" msprop:MyDataType="Image" type="xs:string" minOccurs="0" />
Note that the official type of the field is "xs:string",
because it contains a path to the image. but now it also has the custom
data type tagged on to the column definition. in this respect, i'm glad
to see that MS have provided a very elegant and flexible framework.
Monday, 22 November 2004 16:53:35 (GMT Standard Time, UTC+00:00) .Net General
Thursday, 18 November 2004
System.Net.WebException: The request failed with HTTP status 401: Unauthorized.
I have a WSE2 web service that was working fine until one day i got the above error. i realised i had changed the permissions on the folder (for the web application), so that only System, Adminstrators and ASPNET had permissions on it. Previously the 'Users' group had permissions. By a process of elimination, i found out that IUSR_xx needed to have read/execute permissions aswell as ASPNET, even though the process is running with the identity of ASPNET.
it's strange, but i thought i'd post my solution here in case anyone else comes across this.
Thursday, 18 November 2004 12:45:53 (GMT Standard Time, UTC+00:00) Asp.Net
Monday, 08 November 2004
Asp.Net DataGrid PageIndexChanged not working
i have an asp.net custom server control (deriving from a datagrid) and it has built in paging, sorting and databinding. i ran into a weird problem, and thanks to Rick Strahl's post on http://west-wind.com/weblog/posts/211.aspx i was able to get it working. Read that page first because there are many solutions posted for this weird error.
i'm using regular paging, and the next button works fine (all the time, for multiple pages), but if i click previous then a dud postback happens and the pageIndexChanged event doesn't fire. i'm 100% sure that the eventhandler is hooked up, it just doesn't fire. the solution in my case was to bind the datagrid in the control's PreRender method instead of in the OnInit method. it just worked fine after doing this.
Monday, 08 November 2004 18:33:01 (GMT Standard Time, UTC+00:00) Asp.Net
Wednesday, 03 November 2004
using the same WSE2 web service with 2 different policies..
did you know you can configure multiple policies for the same web
service? it's possible because endpoint uri's are case-sensitive,
so you can have WebService1.asmx and WEBSERVICE1.asmx, which are
treated as separate web services in the policyCache.config file. see
the sample below:
<request policy="#username-token-signed" />
<response policy="" />
<fault policy="" />
<request policy="" />
<response policy="" />
<fault policy="" />
the first one uses a username-token-signed policy for
authentication. clients who wish to use this policy must have a
reference to the web service matching the case of the endpoint uri
the second endpoint has no policy enforcements and this means even a non-WSE request can use the web service.
some WSE implementations, (especially custom username tokens..) will
have a method like "checkAuth()" that every web method calls at
the start to verify programattically that the message obeys the
rules. this method throws soap faults for any missing
WSE elements in the message header. in my case, i want to
allow requests originating from the web server itself (.aspx pages
using the web methods) to bypass the authentication checks, so
i put the following lines of code at the top of my "checkAuth()"
method to allow requests made on the same server to go through:
// allow local ws requests to bypass security
if(HttpContext.Current.Request.ServerVariables["REMOTE_ADDR"].ToString() == "127.0.0.1")
return; // skip further checks
i could also invoke the web methods using the web service class
directly, (not go through a web service proxy) because it's within the
same assembly, but i'm sure there are circumstances where this approach
may prove useful. if you find any, post them here as a
comment, i'd be interested to hear.
Wednesday, 03 November 2004 17:43:16 (GMT Standard Time, UTC+00:00) Asp.Net
Tuesday, 26 October 2004
TextBox.Focus() doesn't work within Form_Load
i have a windows form with a textbox inside a panel, and the following code doesn't work as expected:
private void WizardLoad(object sender, System.EventArgs e)
Thanks to someones post:
i now know that the best way to do it is as follows:
this.ActiveControl = this.txtUsername;
Tuesday, 26 October 2004 12:06:57 (GMT Daylight Time, UTC+01:00) .Net Windows Forms