Tip of the Day: Creating a control that displays multiple types of messages using the IValidator interface

My first journey through expression trees and dynamic lambda expressions, and an explanation on how I got there. The end result is a case-insensitive search and a wildcard search function.

Tip of the Day: Manipulating ASP.Net validators client side

How to register class based user controls in a web project

Extension method for providing dynamic sorting based on field names of a List collection.

Read more ...

Two useful menu items to help eliminate "using" clutter in VS2008.

More promising features of VS2010

Tip of the day: marking routines obsolete, and enforcing it!

Some of the great features of Visual Studio 2010 which are very appealing to me!

Using generics to simplify getting data from a SqlDataRow or DataRow object.

Launch another program, and optionally wait for it to complete.

A simple validation routine to validate a string meets the minimum and maximum length requirements.

WinForm: The base class % could not be loaded.

Using the MasterType directive to programatically access you Master Page.

Just a general rave about WebSpark, and a rant about PayPal.

Interview question -- the virtual keyword

Fancy tooltips in WinForms!

Adding a WinForm tooltip without the control..

I am getting settled in my new project, and it only took me a week to get rights to install anything on the laptop! A lot of people would say "Wow, a billable week with no work!" but personally, the days just drag by. I'd much rather be buried in code. I did make some good use of the time though, digging into what documentation I could find and creating a new Functional Specification Document. I did finally get my rights, so tomorrow will be spent installing things and looking into code again.

I did get some reading done though, and I saw that in VS2010 C# will have optional and named parameters. I know the VB crowd (of which I come from) will chuckle a little at that, as that feature has been around forever. Until now, it's required C# developers to overload functions. Nothing Earth-shattering about this feature, other than as part of it, C# will support named parameters and default values as well as part of the implementation (the default values are part of the defiinition of the function).

As I was looking through Scott Hanselman's List of Tools for 2009, I saw a reference for Microsoft's Sketchflow (part of Microsoft Expression), which allows you to design (among other things) and work through ideas prior to coding. I am going to check it out this weekend, and maybe some of the alternate tools he recommended for his post.  I might even have to dust off my Table PC, as it seems like a good combination.

Tipf of the Day: A brief discussion of the new Extension Methods in .Net 3.5

Starting a new project, how to approach it?

I posted about sp_findsp previously and decided to revisit it. I didn't write it (see previous post for credit/link) but I did add a bit to it. First, I cleaned it up a bit to make it easier to read, and second, I made it so that it is a system proc so I could access it from any db on my server. I may end up doing some cleanup on it's output, but that's all I had time for for now. So here goes, the new version!

USE master
GO

PRINT 'Checking for the existence of this procedure'
IF (SELECT OBJECT_ID('sp_generate_inserts','P')) IS NOT NULL --means, the procedure already exists
BEGIN
PRINT 'Procedure already exists. So, dropping it'
DROP PROC sp_findsp
END
GO


CREATE PROC sp_findsp @s varchar(255)
AS
BEGIN
    DECLARE @msg varchar(255) ,@ul varchar(255)
    SELECT @s='%' + @s + '%'
    
    SELECT 'SP Name'=upper(o.name), Seq=colid ,'SP Line'=substring(text,patindex(@s,text)-5, 30)
    FROM syscomments c , sysobjects o
    WHERE o.id=c.id
    and patindex(@s,text) > 0
    ORDER BY [name]

    SELECT @msg='* Stored procedures containing string "' + @s + '=' + convert(varchar(8),@@rowcount) + ' *'

    SELECT @ul=replicate('*',datalength(@msg))
    PRINT ' '
    PRINT @ul
    PRINT @msg
    PRINT @ul
END
GO

--Mark procedure as system object
EXEC sys.sp_MS_marksystemobject sp_findsp
GO

PRINT 'Granting EXECUTE permission on sp_findsp to all users'
GRANT EXEC ON sp_findsp TO public

GO

When I go onto a client site, I usually don't have the luxury of designing everything from scratch. There are times (like on my current engagement) if I were given the choice, I'd say scrap it, but usually it doesn't happen that way. It is what it is... been saying that a lot lately!

So one of the tools I find useful is the ability to search for particular field names in the database. This is very similar to sp_findsp I use, which I have posted in the past off the net, but I have modified it so it gets registered as a system procedure.

So here's sp_findfields. It will return a fairly printable representation of the results of all fields which match the passed in string. It's registered as a system procedure in this script, so it is accessible to all databases.

Usage:

sp_findfields '%Contact%'

This will find all fields with the string 'Item' in it. Note you need to provide the wildcard characters.

USE master
GO

IF (SELECT OBJECT_ID('sp_findfields','P')) IS NOT NULL
    BEGIN
        DROP PROCEDURE sp_findfields
    END
GO

CREATE PROCEDURE sp_findfields
(@searchText varchar(50))
AS
BEGIN
    
    SELECT SchemaName = LEFT(TABLE_SCHEMA,10),
        TableName = LEFT(TABLE_NAME, 35),
        FieldName = LEFT(COLUMN_NAME, 40),
        DataType = LEFT(DATA_TYPE, 13),
        DataSize = CHARACTER_MAXIMUM_LENGTH,
        AlloysNulls = IS_NULLABLE
    FROM INFORMATION_SCHEMA.columns
    WHERE column_name like @searchText
    ORDER BY TableName, FieldName
END
GO

--Mark procedure as system object
EXEC sys.sp_MS_marksystemobject sp_findfields
GO


GRANT EXEC ON sp_findfields TO public
GO

Normally, I don't have enough time to really dig into the bleeding edge technologies, but I am trying to rectify that. The question is always "When is it too early.."

For now, I have been looking at some of .Net 4.0's newer features, and one really cool thing for environments which have years of legacy software is called "Multi-targeting". Essentially, it allows you set the target environment for an application in the same IDE (but later target new versions).

As an example, let's say you are currently using ASP.Net 2.0, and you have to because of client concerns. No problem, you'll be able to set the VS IDE to target the 2.0 framework. However, when you decide to upgrade, you can just change the target framework version. The neat thing is that the IDE willl hide and show Intellisense based on the target framework as well.

Scott Guthie is writing a series on it I plan on following closely. This time, I may just have to be more bleeding edge than I have been in the past.

The following code snippets make retrieving values from DataRows safely, and properly casts them to the desired values.

 

I am a huge fan of CodeSmith. If you are not familiar with it, and you do any amount of coding at all, you owe it to yourself to check it out.

Below is some template code which loads the foreign keys of a table into a Dictionary object. It stores the name of the table and foreign key field name. As you can see, it generates a notice when it comes across a recursive relationship.

 

public Dictionary<string,string> GetForeignKeyTables()
{
    Dictionary<string,string> dic = new Dictionary<string,string>( );

 for (int idx = 0; idx < SourceTable.ForeignKeys.Count; idx ++)
 {
        string primaryTable = String.Empty;
        string primaryKey = String.Empty;

  // To get the foreign key columns
  ColumnSchema col1 = SourceTable.ForeignKeys[idx].ForeignKeyMemberColumns[0];
        primaryKey = col1.Name.Trim();

  // To get the foreign key tables
        primaryTable = SourceTable.ForeignKeys[idx].PrimaryKeyTable.ToString().Replace("dbo.",String.Empty).Trim();
        if (!dic.ContainsKey(primaryKey))
            dic.Add(primaryKey, primaryTable);
        else
            MessageBox.Show("This table may contain recursive relationships. You must set those relationships up manually.");
    }

    return dic;
}

 

An example of reflection in coding!

Today has been an insanely busy day, but I have so much I want to blog about, and this one won't wait. A few days ago, as I was using some code I found on the net, I commented here about the over-use of the var keyword.

Seems I am not the only one who has an opinion on the matter. I subscribe to the CodeProject newsletter, and each issue features a survey. This week, the survey relates to the opinion of the var type in C#. You can see the survey results here. Make sure you click through to the "optional text answers" for some funny comments (and a few relevant ones as well).

The interesting thing to note from the survey is that the answers tend to skew towards the "never use that scenario" range. The two areas where it is most prevalent is with LINQ, and with anonymous types, which makes total sense.

Question: What's reflection, and how have you used it to solve a problem?

Answer: Reflection is a way to look at assembly metadata and look in and see what is contained. It also allows you to use late binding and call methods within those assembles.

For the second part, a simple explanation is all you need to show that you understand how it is used.

So what if you've enver used reflection? First, shame on you (kidding!). It DOES serve a very important purpose and allows for some great solutions, especially at an architectural level. If you've never used it, I recommend immediately trying it out, and you'll find many, many uses. Here's a tutorial I found that looks decent. That way, when asked this question (and I get this one a lot) you can answer how you *might* really use it. Honestly, you've probably used it and didn't realize it if you've added certain attributes to your code.

I have used reflection for everything from identifying certain classes and functions. For example, for a coding sample, I used LINQ for Reflection and attributes to identify classes which supported certain calculations. By doing this, I could add more functions dynamically and the UI would pick it without changing code. Since LINQ for Reflection is not discussed much, I'll post some about that later.

There are some costs associated with Reflection though. Speed! Late Binding is slower by it's nature, as well as all the processing looking for methods, so plan and use wisely!

As a full time developer, I search the web... a lot. If you are writing a lot of new code without at least searching to see what exists, you're either getting paid by the hour (or line of code), stubborn or a glutton for punishment. Even if I don't use it, I can get some guidance on what someone else tried, and how it worked out before I start coding. Granted, it usually requires a lot of refactoring the code to my standards or needs, but it's a great start.

As I was thinking of things I wanted to put on my site, I realized it would be nice to share my "favorites"...sort of. If I found something useful, I wanted to be able to show what it was, how I found it useful and where someone else can find it. In a way, I am also helping to promote someone else's hard work and improving their search engine visibility to return the favor of their sharing their work.

Out of this, I came up with an idea for a "Useful Links" section. I wanted to be able to add links and commentary, and also add it to my Activity Aggregator to show help show the content of the site has changed. Later, as I was using Bing, I got the idea to add some webthumbs to enhance the page graphically, so the reader would know what the site looked like before going there. I also needed to add an admin page for creating the useful links (and ultimately maintaining them -- which is on my TODO list). I'll also leave out the icon creation part, although I really need to farm out for a new cool looking icon, which is also on my list of things to do.

I'll skip the admin section, as it's just data entry fields. The process for creating the entries does change a bit, as I needed to do a few extra steps.

1. Save the UsefulLink class
2. Default the webthumb image to a default "safety" image in case we can't get a webthumb
3. Make a request to get a webthumb image of the target site
4. Once the image is retrieved, update the UsefulLink record to point to the new webthumb
5. Update the Activity Aggregator to show we have a new useful link.

Step 3 is where things get tricky. How in all getout do we get webthumb images? There are controls out there you can get, and they are reasonably priced as well. But I decided to keep searching so I could write this one on my own, as it seems like an interesting challenge.

My next thought was to create my own service to do this. There's plenty of code out there, but the easiest way to do this would require some WinForms programming. Don't get me wrong, I LOVE programming WinForms. The problem is I don't want to have to install it everywhere I am at, as I need a service. I could possibly create a Web and Windows service to do this as well, but that seemed overly complex. So I did a search, and I found this, which is a service which does it for you. What's even nicer is that they expose a nice API to use. As of now, the first 100 images a month are free, and after that, the fees are very reasonable. Even though I doubt I will go over 100 images per month, I am so impressed I may pay just to keep the service going.

I was also able to find some c# code to make learning the API fast. I did end up changing it some, but in general it worked very well. You can find it here.

So when the service returns with my image (I used the medium size), I save it to a thumbs directory (had to add write permissions to the directory, or I got an obscure GDI+ error), and call a method on my UsefulLink class to update the record with the thumbnail image. I name the image with the current date and time so that the names will be unique as well.

Finally, once I have downloaded the image and updated the UsefulLink record, I add a call to my Activity class which creates an entry for the Activity Aggregator. As I add more items to throw into the Activity Aggregator, I am considering refactoring things to do some delegate multicasting for all the updates, or perhaps creating a factory where you provide class (should be easy since my business objects share the same base class) or interface, and it knows how to create the activity record instead of making individual calls. That's on my list down the road. :)

Here's what the Activity Aggrgator looks like, with a special Useful Link icon():

 

And here's what the Useful Link section (which has the webthumbs) looks like. I will only be showing 10 at a time to save web page real estate. But I also don't want to lose older links off the page. I am debating now whether to use paging, or just have a smaller hyperlink-only section below the most recent links. I am leaning towards paging, as I have a very neat service I want to implement which makes paging and sorting incredibly fast and easy (more on that someday.. I need to upgrade it to user .Net 3.5 functionality before I post it).

 

Usage of the "var" variable declaration and readability.

I needed to use LINQ to XML to grab some RSS feed information into a BusinessObject I created to save to a database. Here's what I needed:

I have to get some landscape rock put out before my home owner's association has a cow, but I decided to do some more work on my activity aggregator. Today, I decided to integrate my blog feed into it, so when I post here, it will automatically update this activity on my home page (and soon to be in my developer's area).

Here's what the end result looks (for now).

Doing it was fairly easy with the design I implemented in my last post. My BlogFeed class inherits the BaseFeed class, which means I need to implement the ParseFeed() method. Since the RSS feed from my blog is XML, I was easily able to adapt the same code from my TwitterFeed class to work for this RSS feed (which should actually work for any RSS feed I pass in).

I also created another Extension method (for practice) to convert the RSS feed date time to a C# DateTime object. I will post that code as "Tip of the Day" but I have to give Dan Wahlin credit for it, as I adapted some sample code he provided.

Here's how the RSS feed (aka BlogFeed) uses LINQ to XML for creating my activity object.

Tonight was a very enjoyable night of coding. I created the first phase of my "activity aggregator". I actually had a more clever name for it, but being tired, it slips my mind right now.

Currently, I post several places.. short updates for on Twitter. Longer discussions end up on here, my blog. I have some other sources I plan on integrating over time, such as links I found useful (similar to Digg, but also where I can place why I found it useful). That means growth, and when it comes to design, it's best to design change into it up front.

The first thing I needed to do was create my table and business object to collect these activities. In my table, I store ActivityDate, what type of activity it was (foreign key to another table -- ActivityType), a brief summary of the activity text, and finally the url someone interested could click on to get more information. The internal members of my activity class look like this:

Some tools I downloaded today which appear VERY useful, and touching on the ORM topic.

Tonight I didn't get as much time to work on the site as I would have liked, so I focused on getting the admin pages up on the production server so I could do some "behind-the-scenes" work remotely. This required some security, which I started last night, but the data migration for that was a bit more daunting, so I needed to finish it tonight. While the authentication providers and controls do handle a LOT, it has an interesting learning-curve, and deployment can be a challenge as well. All-in-all, it sure beats writing all that code by myself.

I tried to use a lot of caching and cached settings to help improve the performance on certain pages, especially my client list. On my admin pages, I made sure to create a means to reset that cache without having to do a complete server reset. Actually, the same approach I took would work well for high availability sites, as the method I used to complete this would not require a server reset to re-load systems. When I was int he banking industry, high-availability was a huge issue, and simple config changes meant waiting for a scheduled system outage or worse, an emergency outage. When I redesigned that site, that was one of the top priorities I had.

It occurred to me how much time it takes to set up the infrastructure of a site: master pages, common libraries, configuration files, CSS, etc. Once those are done, if done properly, the rest of the site should go fast. One thing I have found to speed that up was the use of Visual Studio Project Templates. Combined with code generation like CodeSmith, you can really generate web sites extremely fast, and get on to coding the "fun" items. I will write about both of those in the future (CodeSmith and Project Templates) once the site is stabilized.

Tomorrow night may not have a lot of development, as my parents will be in town. Later this week, I will be coding my next control: the activity feed. When posts and feeds are made or read, this control will snag it, and place a brief "teaser" on the home page.

I finally managed to get my client list online today. From a technological standpoint, it was pretty straight forward. I store the information in the database, and use my CodeSmith templates to create a class for extracting the data, and then use a Repeater to present the information in a table format. I still need to make some changes to it, but all in all, it works well. Since the data won't be changing often, I did cache the data to make it come back faster.

I started working on security for my Administration pages. I need to get that set up before I can activate the admin pages, but I have run into some issues getting it all configured. I ran into this once before with the ASP.Net forms authentication security provider, but this time is a little different, as I only want to secure one folder. Certainly not too difficult to do, but not as easy as I would have hoped either.

Once I get the security and login page worked out, I'll begin working on my "links" page. The idea here is that when I blog, or post to twitter, or a few other ideas I have, it will update the dark blue control on the home page with a summary and hopefully someone will click through to get the rest of the details. This should be fairly straightforward to do. Since most of the services respond in XML, I'll just use a factory method to instantiate the proper object, which will know exactly what information I want to extract from the XML feed. As I add more items I want to track, I will simply have to implement the same interface and it will plug right in to my "updater". For the items which return XML (e.g. RSS or Twitter), I will use LINQ for XML to grab just want I want and populate the data right into my classes.

Which brings up a point...

I could probably do this almost as easy with XPath. When does it make sense to move to the more "sexier" technology as opposed something proven and works well? For example, a lot of times, when a new technology is rolled out, it tends to be buggy and some of them historically have not performed well (e.g. early XML for those who have been around a while). All things equal, when does it make sense? Just a rhetorical question, but one I got hit with recently.

I was in a technical interview for a job I wasn't planning on taking (drive was too far -- the company I was representing knew this as well, they just wanted me to be on their radar for the future). I was asked about a particular implementation of the new List object. Honestly, I know how to use the List object, and he was asking about some of the internals I really hadn't needed to know.

If I was having performance issues, I would want to know, and then I would look into it further. In this case, I was able to provide at least 4 other reasonable implementations based on the criteria I was given, yet, I still couldn't get the "sexy" answer he was looking for. At what point does it really matter? For my part, I didn't like NOT knowing, and I did look it up when I left, but in the big picture, when does it become relevant? In my book, the practical solution to a relevant problem always supercedes technical "sexiness".

A plug for my company, Rubicon Computing Solutions, LLC.

Using LINQ to XML to work with the Twitter response, and modifying the Yedda Twitter API wrapper.

Note: For visitors of your site, this entry is only displayed for users with the preselected language English (United States)/English (United States) (en-US)

How the VS2008 IDE is very helpful to conditional compilation, and also how the site is coming along

New Data property of the Exception class is quite useful!

A new blog...

Re-inventing an outdated but very useful wheel....

Is it just my installation, or is WinCV missing from the latest version of .Net? Granted, I can still use the old WinCV by changing the config file, but why was such a useful tool pulled from VS2005?

If you've never used WinCV, check it out for VS2003 and prior version. It essentially lets you search the framework for a certain keyword. For example, if you want to find out which namespace "Registry" is in, type it in, and see the entire implementation. By using the configuration file, you can add additional assemblies for WinCV, to search your own libraries or those of third party vendors.

 

Previously, I discussed how I worked around a firewall issue where the HTTPS port was re-mapped, and the return URL was different than the request URL as a result of that remapping. So I trudged on, and hit a real stumper. Here’s the new issue:

 

The underlying connection was closed: Could not establish secure channel for SSL/TLS. Inner Exception: The function completed successfully, but must be called again to complete the context

 

I ran across Jan Tielen’s blog post (http://weblogs.asp.net/jan/archive/2004/05/08/128394.aspx) where he provided a code snippet to override the GetWebRequest method in the Reference.cs file. I implemented it, and it worked great --- on my development machine! However, when rolled out to the same test environment, the problem remained. However, I modified it futher, and got it to work..

 

/// <summary>

/// Set web request properties here

/// </summary>

/// <param name="uri">uri </param>

/// <returns></returns>

protected override System.Net.WebRequest GetWebRequest(System.Uri uri)

{

   System.Net.HttpWebRequest webRequest = (System.Net.HttpWebRequest)WebRequest.Create(uri);

   webRequest.AllowWriteStreamBuffering = true;

   webRequest.KeepAlive = false;

   return webRequest;

}

 

Sort of. When I tried to use DIME with the above code, it gave me an error “Client found response content type of '', but expected 'text/xml'”. That was not going to work. I found some more code, and it seemed to work great once again, until I tried to make a DIME call. Here was that attempt.

 

protected override System.Net.WebRequest GetWebRequest(System.Uri uri)

{

     WebRequest request = base.GetWebRequest(uri); ;

     if (requestPropertyInfo==null)

         requestPropertyInfo = request.GetType().GetProperty("Request");

     

     HttpWebRequest webRequest = (HttpWebRequest)requestPropertyInfo.GetValue(request,null);

     

     webRequest.KeepAlive = false;

     webRequest.ProtocolVersion = System.Net.HttpVersion.Version10;

     return request;

}

 

Once again, it worked fine during my WSE calls, but failed when trying to use DIME attachments with the following error:  found response content 'application/dime', but expected 'text/xml'

 

To save any readers some time, I will go through everything I tried to resolve the problem, and finally, how I ended up resolving it. Here’s the items which didn’t work:

 

-- tried setting the SoapActor

-- tried turning off the Document protocol

-- tried setting the request and return URI

-- tried overding the GetWebRequest function a few different ways

-- tried using wsdl instead of asmx in setting up the Web Reference

-- tried setting the URI target/destination seperately

-- moved web service to the same machine as the calling web site (but still had to make an external call)

-- turned on tracing input and output and analyzed the logs created by WSE 2.0

 

So what finally worked? I ended up abandoning DIME, and encoded the file as a string, and passed it as an element of my XML. Here’s the code to encode the file as a string.

 

/// <summary>

/// Encodes the file in a Base64 string format.

/// </summary>

/// <param name="file">Name of the file.</param>

/// <returns></returns>

private string EncodeFile(HtmlInputFile file)

{

      try

      {

            if (file.PostedFile.ContentLength > 0)

            {

                  byte[] fsBytes = new byte[file.PostedFile.ContentLength];

            System.IO.Stream fileStream = file.PostedFile.InputStream;

            fileStream.Read(fsBytes, 0, file.PostedFile.ContentLength);

 

            return Convert.ToBase64String(fsBytes);

            }

            else

                  return String.Empty;

      }

      catch (Exception ex)

      {

            //Handle the Error

            return String.Empty;

      }

}

 

What a trip it was to get there, but the resulting service has performed well, and I don’t have the issues I had with DIME. Don’t get me wrong, DIME worked great. But deployment of the web service in a secure environment proved to be quite a challenge. If you need more detail in resolving your issue, feel free to leave a comment or shoot me an email, and I will be glad to save you some of the pain I had to go through!

Just a little tip, as I didn't read the error message generated as closely as I should have. I was working this weekend on the Microsoft Code Template for Building a Provider Based Feature and was migrating some existing libraries I had for VS2003 to take advantage of the features in VS2005.

First, let me say I love things in VS2005 like Generics, and the implementation of the Provider Model. I was migrating my data access libraries and error handling libraries, and was setting up some tests in nUnit as part of ongoing testing. Although I haven't changed my data and error handling models in a long time, I figured it was a great design idea to be able to change them dynamically using the Provider Model.

To make a long story short, I was running my tests for the data library, and when I invoked my Data Access classes, I was getting a "TypeInitializationException" error. I checked and double-checked my configuration file, and it appeared to all be correct. I looked at the InnerException, and it didn't seem to be much more help. However, I went further to look at the InnerException of the InnerException, and there's where I found the solution. The Rosetta Stone?

• Only one <configSections> element allowed per config file and if present must be the first child of the root <configuration> element.

A quick check indicated that I hadn't made the configSection the first element. Doh!

So there are a few lessons to learn here. 1) Make sure your configSections is first (normally not a problem, just a cut and paste issue here) and 2) Make sure you dig REAL deep into the InnerExceptions for the details and 3) the new Visualizers in vs2005 were too cool and very helpful.

Hats off to the VS2005 IDE team! It's spawned a few visualizers I can think of, so if time permits in the future, I will be publishing those right here!

..or why MS has once again dropped the ball on it's core developer community.

"Internal Query Processor Error: The query processor could not produce a query plan. Contact your primary support provider for more information" when passing in C# DateTime value...

When you have to eat your hat...

(and maybe why Extreme Programming (XP) is also bad?)

Need a good developer?

Tired of cutting and pasting? Try CodeSmith...

What the $*#(U$(? Where did the wse version go?

I am joining the fray....

How to get them to reappear...

WTF? Poor documentation...