Tips for returning IDENTITY values from INSERT

There’s a good article by Scott Guthrie here that describes the basics. Just scroll down to Tutorial 5 for the INSERT specific bit – it is pretty straightforward and there is no point my repeating it here.

One point to note, however, and why I wrote this particular post. The key step in getting this working is changing the query type from NonQuery to Scalar. But this can get reset by Visual Studio if you choose the Configure option on the ObjectDataSource’s smart tags to modify the query in any way. If you don’t notice this, then suddenly the identity value stops getting returned and your code breaks.

The second tip is that by default the type returned by the insert query is decimal. This can cause some extra casting in your code if you were expecting it to be int. To fix this, just modify the SQL in Scott’s original article to be this:

SELECT CAST (SCOPE_IDENTITY() AS INT)

Determining row counts for all tables in a database

Here is a usful snippet if you want a way to get the number of rows in each table in your database. I use this in an admin-only page of the web application to provide some at-a-glance statistics. It is also really useful in unit tests for checking the correctness of business logic that may create new entries in several tables in one transaction.

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Formatting code in WordPress

What a pain in the rear! WordPress appears nice as a blogging tool, but my attempts to format some code snippets was painful beyond belief.

Every time I pasted some code in and surrounded it with the code tags, the generated HTML had extra paragraph markers and line breaks, and screwed up the position of the closing code marker.

Even a search for plugins did not cure things. I installed one or two “code formatting” plugins that made things a little better, but still required a lot of post-paste editing of code to get anything like presentable.

It turns out that the Rich Text Editor in WordPress 2 is to blame – it completely messes up. So my advice is to disable this from your user profile.

The thing that rankles is that the rich editor is enabled by default. I did not even know it was optional until I did a Google on code formatting in WordPress. It all just seemed much much harder than it should.

Anyway, hopefully this snippet will save others the problem in the future.

Useful CSV reader

To aid my unit testing I needed to populate a database with a load of test data. This data needs to be generated by some of the less technical guys on the project and so exporting CSV (Comma Separated Values) files from Excel seemed a sensible approach. So I then cast around for any existing code that would save me having to write a robust CSV parser. The search turned up this on CodeProject:

LumenWorks.Framework

The neat thing about it is that you can get field values either by index position or column name, assuming you put column headers in your file. The column name feature really helps out with maintainance of the test data as we evolve and vary the schema slightly – we can insert columns with no worries about upsetting existing reader code.
It’s easy to use and install in your own project, and the CodeProject article describes the basic usage pattern. At the moment it is just linked in to the unit test framework, but is so useful I will probably make it a part of the core application libary to facilitate importing data from customers as we anticipate some of our customers could have thousands of records to import when they move to our system.

Don’t believe NUnit

Just a quick note about a little problem I found using Nunit (2.2.9, but affects earlier revisions too).

After a bunch of edits to my project, I suddenly started getting messages from NUnit GUI “could not load file or assembly nunit.core”. Try as I could, this would not go away. This included everything from reinstalling NUnit to tracking DLL loading via SysInternal’s Process Explorer tool.
My project is non trivial – a top level solution containing an ASP2 web project, a couple of library DLL’s for the business logic, a unit test executable, and a testing helper library to help cross reference test results against direct SQL calls. As I’ll be writing about in another post shortly, incorporating unit testing into an ASP project is a pain in the rear and so I had been restructuring things. My natural assumption based on the error message was I had messed up something in the linking/referencing.

But it turned out to be an error in the application config file – for some reason NUnit reports this as a DLL missing, not that you have mistyped a bit of config text. I simply had a closing tag in the wrong place – still syntactically correct, however.
This link is by someone else who hit the exact same problem, and he has written about in more detail.

So remember folks: never assume a system generates the correct error message for all circumstances.

Perforce server logging problem

When setting up a server it is often useful to enable one of the logging levels. The admin guide states that you need to do this:

  • p4 set P4DEBUG=server=2


which sets the server logging level to 2. You then need to restart the Perforce server.

However, if Perforce is running as a service (the default under Windows), then this does not work. The reason is that “p4 set” only sets the variable in for HKEY_CURRENT_USER in the Windows registry. However, when running as a service, p4d picks up its environment variables from HKEY_LOCAL_MACHINE. To do this you need to set the ‘-s’ flag. E.g.

  • p4 set -s P4DEBUG=server=2