Archive for category Things to Remember

The specified cast from a materialized ‘System.Int64’ type to the ‘System.Int32’ type is not valid

I ran into a sql related .net error today.  If you read the title of the post you’ve probably guessed what it is.  If not here’s the error:

The specified cast from a materialized ‘System.Int64’ type to the ‘System.Int32’ type is not valid.

Google was marginally helpful, but if you’re like me when you google an error you’re hoping for that post that says:  If you see ABC, then you have done XYZ, do 123 to fix the error.  In this case the error is saying there’s a datatype problem.  Something about a Long and an Int.  My app only has ints.  No longs in the schema at all.  This specific error came out of an entity framework method, so I couldn’t easily pinpoint it to a given column.  98% of my app is pure entity framework, mostly code-first (though I do write out transactional schema patches to update the database in a scripted manner.)  There is one stored procedure in the app, and this stored proc I had just changed to add some new features specifically paging from the sproc.

In this case, the sproc looked like this:

Reports_MyReport SomeGuidID

it returned data of the report, field1,field2, field3 etc..

My change was to add paging directly to the sproc, reduce the amount of data leaving the box as this report was going to get hit a lot.

Reports_MyReport SomeGuid, PageNumber, PageSize

it returns data like RowNumber, Field1, Field2, Field3, TotalRows

I tested out the changes, they worked great, no nulls where they weren’t expected.

Upon running the new sproc through my app, i got the error listed above.  It turned out that my sproc, which had code like this:

select RowNumber, Field1, Field2, Field3, @totalRows as TotalRows  ….

was the culprit.  @totalRows was being interpeted as a int64, as that was comming from an @@ROWCOUNT function.  I know i’ll never have more than int32 rows in that table, so for me switching by casting to Int32 solved the problem:

select RowNumber, Field1, Field2, Field3, cast(@totalRows as int) as TotalRows  ….

Problem solved, error gone!

Hopefully by the time I have completely forgotten about this, and make the exact same mistake again – in six months – this post will be living in the googles.  Hopefully this helps someone else as well.

 

Scott

 

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Cleaning Up with MSpec

I use MSpec for testing my code.  I love the behavior driven approach, for me it just makes sense.  I love how if my boss asks where are we with component XYZ, I can just run all my tests and give him the output.  It shows what’s working and what’s not.  Further more, we can say or make a rule that software doesn’t have a feature until there’s an mspec test saying that it does.

I was recently working with mspec doing integration tests – these I usually do to make sure my DAL and my database are structurally compatible – and I kept getting database constraint errors when I reran tests.  It didn’t make a lot of sense as I had a cleanup section in my code and I wasn’t seeing any errors.

It turns out, that if an exception is thrown in the cleanup section you’ll never hear about it.  At least for me, it doesn’t bubble up.  Once I put a breakpoint on the first line of the cleanup I figured it out.  Previously I was thinking it wasn’t even hitting my cleanup code.  It was hitting the cleanup section however, only there was an error in that section.  Hopefully this gets into the googles and helps someone.

using Machine.Specifications;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace My.Project.Integration.Tests
{
    public class when_creating_a_mything_record
    {
        protected static IMyThingService MyThingService { get; set; }

		protected static MyThing MyThing { get; set; }
		protected static MyThing SavedMyThing { get; set; }

		Establish context = () =>
        {
            MyThing = new MyThing() {
				Name = "thing",
				Description = "thing one"
			};
			MyThingService = ServiceLocator.Instance.Locate<IMyThingService>();
        };

        Because of = () => Exception = Catch.Exception(() =>
        {
            SavedMyThing = MyThingService.Insert(MyThing);
        });

        It should_not_have_thrown_an_exception = () => Exception.ShouldBeNull();
        It should_have_an_id_that_does_not_match_guid_empty = () => SavedMyThing.ID.ShouldNotEqual(Guid.Empty);

        Cleanup after = () =>
        {
           // If this does not appear to get called. put a breakpoint here.  You may have an exception.
           MyThingService.Delete(SavedMyThing);
        };
    }
}

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Git Helpful Hint – Just Trust Remote branch

At work I’m often working with others.  However at times we’ll be working in our own projects (read git repositories) and then working together in common shared projects.  The repository that I’m the main developer on and all the shared ones are always up to date but there repositories that I don’t often commit to can find itself lagging quite far behind.  Recently I saw a large number of merge failures when trying to get the latest version of one of these repositories.

Essentially what I wanted to do was to say hey Git, I don’t work on this repository often so trust everything that is coming from upstream and overwrite my stuff.  There were many things that the googles suggested that I could do, but quite a few wouldn’t work in the midst of a merge failure that had already occurred.

This stackoverflow post did work though.

Here’s how you do it:

git fetch --all

git reset --hard origin/master

Be warned, this essentially tosses out all your local changes. So make sure your situation is like mine or similar before doing it.   I figured if I blogged about this, it would help me remember the next time it came up.

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