Category Archives: .NET

vb.net or asp.net or other .net related topic

A google style FTS Full Text Search using MS Sql server 2008

People are used to searching the internet and thanks to google, yahoo and bing everyone can find what they want within a few keystrokes and mouse clicks.
This means that people have been self trained from countless hours spent searching the web using these search engines. We developers can make use of this by providing the same style search in our applications.
Enter the Ivory .Net Language Implementation Kit. What is Ivory ? well Ivory is a developer kit for implementing languages on a .NET platform. You can write your own grammar class to be loaded into the ivory dll in the form of EBNF.
The grammar class basically contains the logic behind how we will provide a Google style syntax for our search engine. Using either c# or vb.net writing in the Extended Backus Naur Form (EBNF). Now i don’t profess to be an expert in EBNF, far from it in fact. I simply want to use the already built class found in this kit “FullTextSearchQueryConverter” found in Irony.Samples.FullTextSearch called SearchGrammer and insert it in between my search form and the database call.

The first thing your going to need is the kit, you must download it from here Irony Kit Once you have downloaded it and had a little test of your own you are likely ready to implement it.

Before you continue its in your interest to already have a search facility built that uses the full text search engine in sql server

Let’s beginPersonally I code in vb so I converted the SearchGrammer Class SearchGrammer
Add the aforementioned class to your project.
To integrate this into our search tool you need to locate the area just prior to where you called your Full text Search crunch against the DB.
I integrated mine in the following way.

1. Instantiate our Irony dll and load the grammer class
2. Run the search text through the engine to generate the fts clause
3. Verify there we no errors
4. Pass FTS to db call

Personally I instantiate the Irony class and load the search grammer when my main search class is instantiated.

From a topographical perspective this is the code needed to execute this type of search from anywhere in my application

Where qry is the search object containing amongst other things the search text from the input, and oDS is the returned results from the query
Line 1 instantiates the FT search class, this instantiates the irony dll and loads the searchgrammer like so.

To use this to generate the full text search query I can now perform the following from any part of the class

Where FriendlySearchString is the input string from your user, and ftstring contains the TFS search query we can pass over to which ever means you are using to build the query.
The last thing you will need is the CheckParseErrors() method

I posted a discussion within the irony forum that says a similar thing to this post found here

I hope this helped those who needed a how to on implementing irony as your google style FTS generator in your .NET apps.

How to make a copy of a NameValueCollection

This is a rare requirement but should you need to heres how

Where New_NVC is your new declared NameValueCollection and OLD_NVC is the NameValueCollection you wish to copy.

How to convert NameValueCollection to a QueryString and visa versa

I needed a full proof way to desipher a querystring that might potentially be slightly malformed
Similarly i also needed a way to build up a querystring, potentially replacing existing values while building the string

So a malformed querystring could be

http://domain.com?&v=1&&&x=y

I say malformed, this isn’t strictly malformed but if you tried to split this into an array of strings you might run into errors
So to pull this into a valid collection you do the following

Then to perform operations on the collection simply do the following

Here’s how to build a querystring, including easy ability to change existing values and turn it into a valid encoded querystring in one line

The output of FinishedEncodedQueryString is

“?q=replaced+value&ch=something+with+a+space”

user control is ambiguous in the namespace ‘ASP’

This one was a particular pain.

Long story short try this in your web config

Set batch=”false” under compilation

This will allow you to drill further into the problem, its not a particularly desirable attribute to set in production.

Visual Studio VS 2010 not stopping at breakpoints

Ever wondered why suddenly you cannot debug because the compiler isnt breaking on your breakpoints.

There are several reasons for this.

make sure that.
1. Your project is compiling when you begin debugging (check this in build > configuration manager)
2. Ensure your projects are compiling in debug mode not release (check this in build >configuration manager)
3. In the Webconfig ensure you are in debug mode

4. The (project properties > startup options > debuggers has the ASP.NET checkbox checked)
5. Delete all pdb files in your bin folder
6. Ensure every project referenced is set to build under (build > configuration manager)
7. Do a full clean and rebuild. (build > clean solution) (build > rebuild solution)

Finally and this is the one that caught me out
8. Check you are not setting a cookie cache timeout of positive time, I was expiring my page after 1 day. The best way to check this is to load a page in debug, knowing your break point will not be stopped at. Once the page is fully loaded hit ctrl F5 to force full reload of the page. If your breakpoint is stopped at then you know its a cache problem.

ASP.NET Master Page Nested inheritance

I seem to be asked this a lot so i thought i would mention this online so hopefully people will no longer ask me, they’ll find the answer when they ask google

You are trying to inherit from a masterpage and you recieve the following error

the page has one or more < asp:content> that do not correspond with < asp:ContentPlaceHolder> controls in masterpage

Script tags are the culprit around 80% of the time. For some reason the visual studio designer doesnt like not fully closing your script tags at design time.

Change all of you script tags from this

< script type="text/javascript" src="js/myjs.js" /> 

correcting it to this:

< script type="text/javascript" src="js/myjs.js" ><  /script>

Any you should be good to go.

VAT Information Exchange System (VIES)

What is the VIES ?
It is an electronic means of transmitting information relating to VAT-registration (= validity of VAT-numbers) of companies registered in EU. Furthermore, information relating to (tax exempt) intra-Community supplies between Member States’ administrations is also transmitted via VIES

The Taxation and Custom Union has provided us developers a nice little webservice to use for validating VAT numbers realtime.

This is their public facing page for one off manual validation
http://ec.europa.eu/taxation_customs/vies/
The service to be used by your application can be found here
http://ec.europa.eu/taxation_customs/vies/checkVatService.wsdl

The FAQ is here http://ec.europa.eu/taxation_customs/vies/faqvies.do

Ok so now i will demonstrate how to use this in your Visual Studio based application

If you have Visual Studio 2010, and your building a web app, in solution explorer right click the web app root node and you should see “Add Web Reference”, this will present you with the “Add Web Reference” dialog box
Paste the above web reference link into the “URL” and hit the “GO” green arrow

VIES Visual Studio Web Reference

Now Hit “Add Reference” and Visual Studio creates the Web Server Proxy and Wrapper Class.
Ok so now your project has the reference lets see how to use it

On your page that you wish to validate a vat number you should do the following
1. Collect a valid 2 character country code from the User
2. Collect a valid vat number from the User
3. Perform the needed filter on both of these values prior to envoking the webservice
4. Verify the return from the service and take action

First off you will need to import the reference into your page. For ease I use asp.net vb, C# will be similar and there are plenty of converters out there to see the code in c#

now your ready to use the reference
For this example we will be supplying country code and VAT number only. There are various other methods available but this suited me so its the only demo you will be getting.
The rules
1.The country code must be valid
2. The VAT number must contain no spaces and only be numerical numbers
3. We pass the validation boolean as a byref, if you also wanted to see what the company name and address the EU have on file for the company the webservice verified, you can pass two strings “Name” and “address” byref and view the content upon return.

This is how i do it

Most of the above code is preparation, there are very few ines tha perform the webservice method.
The actual call is made in the try catch

My particular app verifies the value of IsValid in the calling function, how you validate the values is up to you, on asuccessful return the value will be true and the byref Name and Add will contain the registered company name and address.

For your reference there is also another way to reference the web service described here http://softwareobjects.net/technology/other/vies-vat-number-checker/

LINQ to Entities does not recognize the method ‘System.String ToString()’ method

If you use the entity framework from microsoft, latest version at the date of this post is framework 4.0
You might run into this little angel when you try to envoke the string value of an object

LINQ to Entities does not recognize the method ‘System.String ToString()’ method

This happens when applying a filter to an integer field and you want to use the

method of a string. So my code looked ike this

From the master query

etc…

The only way i Could get round this was to onvert the UID field into a string in the master select query like so

notice the cure was to force linq to convert the resulting field into a string, allowing the filter to look like this

Microsoft have a list os supported methods here

Access to the registry key ‘Global’ is denied

If you use performance counters in web based apps you may end up running into this problem,

[UnauthorizedAccessException: Access to the registry key ‘Global’ is denied.]

UPDATE For IIS7 on windows server 2008 (see the end of this post)

The solution is pretty simple, originally posted here

How to Read Performance Counters Without Administrator Privileges [Ryan Byington]
If you have ever tried to read performance counter data on a Windows 2003 machine as a non admin user you will have likely seen an exception like the following:

System.UnauthorizedAccessException: Access to the registry key ‘Global’ is denied.
at Microsoft.Win32.RegistryKey.Win32Error(Int32 errorCode, String str)
at Microsoft.Win32.RegistryKey.InternalGetValue(String name, Object defaultValue, Boolean doNotExpand, Boolean checkSecurity)
at Microsoft.Win32.RegistryKey.GetValue(String name)
at System.Diagnostics.PerformanceMonitor.GetData(String item)
at System.Diagnostics.PerformanceCounterLib.GetPerformanceData(String item)

Windows 2003, Windows XP x64 Edition, and Vista require that the user be part of the Performance Monitor Users group to read performance counter data. Simply adding your non admin user to this group will fix this problem.

Accessing counters remotely is another story though. On Windows 2003, Windows XP x64 Edition, and Vista you still must be part of the Performance Monitor Users group on the remote machine but there is a problem with the PerformanceCounter class where it tries to read some registry keys on the remote machine that a non admin users do not have access to. To give your user read access to these keys without having to be an admin on the remote machine complete the following steps on the remote machine:

Open the Registry Editor by going to the Start Menu and selecting Run…, then type “regedit”, and click the OK button.
Navigate to the HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SecurePipeServers\winreg registry key.
Right click on the “winreg” key and select Permissions. Add users or groups to which you want to grant Read access.
Exit Registry Editor and restart Windows.
For more explanation on this process see here

UPDATE For IIS7 on windows server 2008 (16/11/2011)

This I can’t believe but none the less this is the way it is for IIS7. when you have performed the above steps and you are still receiving the error

Access to the registry key ‘Global’ is denied.

What you need to do is add the App Pool that your web app is running in to the “Performance Monitor Users” group as well. One immediate point is that you cannot find the group within the advanced search when adding objects to the group. You will have to manually type the name of the App Pool following this format

IIS APPPool\DefaultAppPool

Seems ridiculous I know and I haven’t fully got to the bottom of why but I suspect it is most likely something to do with the structure of IIS7 from an NT authentication perspective.

This also now puts an additional rule that one must not rename the App Pool and one must also be vigilant in as much as if you add another web app, creating a new app pool you might need to add this app pool to the group as well.

This updated solution came from here

Datatable to XML CSV TAB HTML Json

I have a common functions class (cfc) project i tend to fill with all functions i believe can be applied to anything and will likely be reused.
I was making some adjustments to a few handy functions and I thought it might be useful to publish the following functions which will help convert datatables to various output formats.

Visual Studio references the following libraries within my cfc project, im not entirely sure which ones are required for these functions so i will list them all.
System
System.Core
System.Data
System.DirectoryServices
System.Drawing
System.Runtime.Serialization
System.ServiceModel.Web
System.Web
System.Web.Extensions
System.Xml

We have 6 functions here
1. ConvertDtToXML
2. ConvertDtToTDF
3. ConvertDtToCSV
4. ConvertDtToJSON
5. ConvertDtToHTML
6. RenderControl

Lets talk about each one briefly.
1. ConvertDtToXML
This function is making use of .NETs Dataset object built in method GetXml, the one simple rule here is that the table must be named in order for the xml to be generated. So we simply declare a dataset, check for a table name, if none then give a standard name, add the table to the dataset and output using GetXml.

2. ConvertDtToTDF
3 things are going on here, the first for loop we get the column headings. Second we begin a for loop on all of the rows, and third we for loop against each column getting the data this time. Each loop builds up the TAB delimited string we end up with.

3. ConvertDtToCSV
A very similar approach to the tab delimited has been taken here with the CSV, its the text used to build the sting that differs.

4. ConvertDtToJSON
We make use of .NETs Json serializer to convert our datatable to a json string

5. ConvertDtToHTML and 6. RenderControl
This final converter function ConvertDtToHTML needs to use last function RenderControl.
Load the datatable into a gridview, bind it, then extract the rendered HTML from it.