Updating Visual Studio Extensions

By Henning Eiben in .Net 0 Comment

Today I wanted to do some overdue updating of Visual Studio extensions. Among others there where an update of NuGet from version 1.6 to 1.7 and for the Visual Studio Achievements from Version 1.6 to 2.0.

But unfortunatly the updated didn’t work as expected. For the Visual Studio Achievements I got an error, that the digital signature did not match and therefore the update could not be installed. For NuGet the message was different, but with the same result. I just got a message, that the update could not be installed.

Doing some quick google research revealt for NuGet, that problemes during updates are somewhat expected. The recommended solution is to uninstall NuGet and to reinstall the new version of NuGet.

I found however a hotfix for Visual Studio, which is supposed to resolve the update problem with the not matching signatures I encountered with the Visual Studio Achievements. This hotfix actually did resolve the problem for the NuGet update as well 🙂

Localizing SpecFlow

By Henning Eiben in Programming, Uncategorized 0 Comment

On a recent usergroup meeting I got introduced to SpecFlow. This opened a whole new world in formulating tests ans specifications. Although I’ve been trying to formulate my tests in a BDD manor, inspired by JP Boodhoo’s and Stefan Liesern’s BDD examples this feels much better.

So the next logical step would be to move to a natural german specification instead of having the original given-when-then syntax.

Turns out, that switching the language is actually really easy. Even though I didn’t seem to find anything on the web … You just have to adjust the app.config like this

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
  <configSections>
    <section name="specFlow"
      type="TechTalk.SpecFlow.Configuration.ConfigurationSectionHandler,
            TechTalk.SpecFlow"/>
  </configSections>
  <specFlow>
    <language feature="de-DE" tool="" />
  </specFlow>
</configuration>

And that’s all that’s to it.

Parameterized queries in MySQL

By Henning Eiben in Programming 0 Comment

In order to do SQL right in the .Net world, you just don’t concaternate a search-term with a static search-string, because this will open all gates to SQL-injection. So the following schould not be used: 

MySqlConnection connection = new MySqlConnection(_connectionString);
MySqlCommand command = connection.CreateCommand();
command.CommandText = "SELECT * FROM Forum where name = '" + forumName + "'";

Instead you should use a parameterized query. Easy, you might say. Just add a placeholder to the SQL-statement and off you go.

MySqlConnection connection = new MySqlConnection(_connectionString);
MySqlCommand command = connection.CreateCommand();
MySqlParameter forumNameParameter = new MySqlParameter("@forumName", forumName);
command.Parameters.Add(forumNameParameter);
command.CommandText = "SELECT * FROM Forum where name = @forumName";

Unfortunatly this doesn’t seem to work alright. At least I didn’t get any results, even though my search-term did exist.

Looking at the actual SQL that was being executed on the server something became obvious.

SELECT * FROM Forum where name = @forumName

That’s not the SQL I was expecting. Somehow the parameter was not being substitued by the actual value. But why?

Just a short test: the same code does work on a MS-SQL database!

Solution

@ is not a valid character for a placeholder in MySQL. Instead  ? should be used. The correct code should look like this:

MySqlConnection connection = new MySqlConnection(_connectionString);
MySqlCommand command = connection.CreateCommand();
MySqlParameter forumNameParameter = new MySqlParameter("?forumName", forumName);
command.Parameters.Add(forumNameParameter);
command.CommandText = "SELECT * FROM Forum where name = ?forumName";

So this finally worked.

Exponention in c#

By Henning Eiben in .Net 0 Comment

To compute 10 to the power 2 shouldn’t be any problem

int result = 10 ^ 2;

As if! Visual Studio strongly believes that the result of this computation should be 8. Damn! ^ is a reserved symbol in c# for bitwise exclusive or (XOR). The correct way to computer this would be

int result = Math.Pow(10, 2);

Supressing Messages from FXCop

By Henning Eiben in .Net 0 Comment

In a recent project I rellay nailed the code using FXCop. The goal was to eliminate all messages of FXCop.

After a short periode of time I already figure: no way! There are just a couple of cases, where I have to irgnore the messages of FXCop. Luckily there is an easy way to supress the messages of FXCop. Just open the context menu of the message and copy the message as SupresseMessage to the clipboard.

suppress_messages

Next you can insert that at the appropriate position within your code, most likely as a method-attribute.

[System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Usage", "CA2201:DoNotRaiseReservedExceptionTypes")]

OK, so now your’re good to go. The next run of FXCop should present you a lot less messages.

And if not? Something went wrong. Some little, very well hidden comment in the documentations says:

The ConditionalAttribute is applied to this class, specifying the preprocessing symbol “CODE_ANALYSIS” as the conditional symbol that determines whether the attribute call is included or omitted. If the symbol is defined, the attribute call is included; otherwise, the call is omitted.

OK. So opening up the project properties and adding the symbol CODE_ANALYSIS helped a lot in getting the number of FXCop messages down.

Errors that actually help to solve something

By Henning Eiben in .Net 0 Comment

Well, suddenly it just happens – a YSOD. Just happened in my recent SharePoint dev-project.

Typical for SharePoint, this error is not obvious. Instead of the YSOD you’ll get a SharePoint specific page, telling you that something went wrong. No hint what happened or where the error actually occurred.

OK, so let’s head to the web.config and stop this hide-and-seek behaviors. I wanna know what’s happening. So we have to enable to show the actual CallStack and disable the use of CustomErrors.

<SafeMode MaxControls="200" CallStack="true" DirectFileDependencies="10" TotalFileDependencies="50" AllowPageLevelTrace="false">
<customeErrors mode="off">

OK, so now we’re talking. I have some sort of Null-Reference-Exception in my code. But this code just worked perfect on my dev-machine, so why is it failing on the test-machine? And why is something null anyway? The StackTrace tells me, that this happened in a property-getter.

private SPGridView _mySpGrid;
public void CreateChildControls()
{
    _mySpGrid = new SPGridView();
}
public bool HasRows
{
    get { return _mySpGrid.Rows.Count > 0; }
}

How can this be null? CreateChildControls is always being called, so the grid always exists. This cannot be the reason why.

OK, let’s try something totally irrational:

public bool HatWerte
{
    get { return _mySpGrid == null ? 0 : _mySpGrid.Rows.Count > 0; }
}

This could should actually not be necessary … except when this modification makes the Null-Reference-Exception to disappear. But just to make room for the next Exception. And now everything is making sense (and I could revert the above modification).

The next exception states:

Could not load file or assembly ‘System.Core, Version=3.5.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089’ or one of its dependencies. The system cannot find the file specified.

D’oh!

My application was build against .Net 3.5 and I didn’t install that on my test-machine. Since the test-machine is a Windows 2003 Server running SharePoint 2007 there was no need to install .Net 3.5 – yet!

But .Net could have told me so from the beginning on – I would have understood this. But instead it was hiding behind some Null-Reference-Exception, just like a coward!