bencoffman.com/blog

System.IndexOutOfRangeException: with a datareader

2010-07-13T21:14:10.884-07:00

Error Readout:
System.IndexOutOfRangeException:

Fix:
I encountered the above error when I tried to run the query,

SELECTMAX(expression
)
FROM tables
WHERE predicates;

and then loop through the results using a datareader with code like this,

while(rdr.Read())

{

someLabel.Items.Add(rdr["ColumnName"].ToString());

}

I got the error above, because when you do a "max" sql query it doesn't return any column header.

All you need to do is give the sql result set a column header.

SELECTMAX(expression) as "ColumnName" 

FROMtable
where predicates;

Explanation:
This is another one of my bone head mistakes. It's such a simple little thing I overlook, and gets me so disappointed in myself when I realize I spent time trying to figure this out. It's generally followed by me looking over my shoulder and seeing if any of my peers saw it. I'm mostly blogging this in hopes I won't make a silly mistake like this again.

Why is it always the baby errors that hang me up the most? It can never be something deep in the CLR, or possibly find a mistake in .Net. Nope, noway, not gonna happen .Net is pretty solid...for the most part.

Debug: Double Backslashes In String, 2 Backslashes in String

2010-06-30T12:10:24.682-07:00

Error Readout:
None, it's not an error silly.

The Problem:
When I debug, and look at a string that contains my file path I see 2 backslashs (escape characters) in my string when I only wanted 1.

The Solution:
It's nothing, don't worry about it, that's just the way Visual Studio "debug" shows your path when you catch it while debugging. When the path is used in the code for the file system there will only be 1 backslash and it will work correctly.

This is such a stupid little thing, but for some reason every once in a blue moon, I forget and freak out on why it's doing this, thus wasting a solid five minutes of my life. I put this post up in hopes I will never forget again and that if someone happens to Google this, my post will pop up and help them move on quickly....maybe only wasting 1 to 2 minutes. :)

Commerce Bank iPhone App

2010-06-25T06:50:55.408-07:00

Apple expects to sell 1 million to 1.4 million iPhones this weekend, this is excluding the 900,000 pre-orders. It has the possibilty to be the biggest selling product release in history!

http://online.wsj.com/article/SB10001424052748704629804575325661775151320.html?mod=WSJ_Tech_LEADTop

UPDATE: They sold 1.7 million. Apple's most successful product release in it's history.

Incorrect syntax near ')'.

2010-06-23T10:41:51.148-07:00

Error Readout:
Incorrect syntax near ')'

The Problem:
When I was trying to pass in getdate() as a parameter to execute a stored procedure i got the above error.

Example:
exec dbo.storedProcedure
    @param1 = '8D8DF077-7491-491B-AFA2-8F088821A073',
    @param2 = '8D8DF077-7491-491B-AFA2-8F088821A073',
    @param3 = 'Market: SAP 4 Eva',
    @param4 = getdate()

The Solution:
A sql execute statement can't pass a function such as getdate() in through a parameter. To fix this either:

Put getdate() directly in your sql statement that resides in the stored procedure
Pass a null if your table definition allows you to.
Create a temp variable store the value of getdate() in that variable and pass in that variable through the datetime parameter.

When to use the * (star) with Objective C

2010-06-12T08:59:04.158-07:00

It's a good question.

There are some types that are not derived from NSObject, these types are called "Primitive Types." Some examples of these types are

int
bool
short
long
double
char

Sooooo basically any type that is not derived from the NSObject class is a Primitive type and does not require a "*".

Now I bet you are wondering how do I figure out if it's a primitive type or not.

An easy way is to look at the color of the syntax in xCode, is it deep blue or a sky blue? Deep blue = primitive type, but this is not entirely reliable as the standards for coloring syntax can fluctuate or change.

You can option-click on the object after you have typed it in xCode, click the little book in the upper right hand corner, when the class reference viewer comes up, look and see if it inherits from NSObject. If it doesn't it's Primitive and you don't need a "*".

Note:
There are some alternatives to using the primitive type int, such as the reference type NSInteger, which has some nice baked in functionality of distinguishing between 32 bit and 64 bit, but not all primitive types have an alternative reference type in Objective C.

Just for fun:
In .Net they have primitive types too(I believe they call them value types), kinda. The compiler recognizes traditional primitive types and therefore lets you use the syntax

int i = 5;

But despite the compiler letting you do this, this type still maps back to System.Int32. All things in .Net are mapped back to System.Object. Everything is a reference type, but .Net lets you keep the traditional syntax instead of writing:

System.Int32 i = new System.Int32(5);

Accessorizer: Hate making those accessors?

2010-06-06T18:12:06.805-07:00

Accessorizer I have been told if you do any kind of serious development in Objective C this is the tool to use. At 15 bucks I'll be making it part of my Objective C toolbox especially since I hate typing out all those accessors (variables, @property @synthesize.) The time saved will surely out weigh the cost.

Why you need to create a controller in some projects in interface builder and not in others.

2010-06-06T18:05:58.127-07:00

When starting a new project you have the ability to select a template of premade projects. Two examples of this are
1. Navigation Based Application
2. View Based application

When these templates are selected xCode will create the appropriate base controller for you in interface builder, such as "Navigation Controller" or a "View Controller" it will also create the appropriate classes for you with some of the most commonly used delegate and datasource methods along with the appropriate methods to override.

With a new project and selecting Window-based application, you are simply creating a blank slate in which you have to create nearly everything. It's rarely advantageous to use this unless, you are creating something outside the templates offered or you are learning how all the pieces fit together.

The Woz is at it again.

2010-05-20T21:56:23.574-07:00

I saw this picture on Dave Mark's blog. Dave is a very talented Objective C developer. The picture really got me so I had to post it.

Enjoy.

Falling Upstairs

2010-05-19T19:34:04.388-07:00

What a wild month! London, Paris (loved Paris), and Barcelona, followed up with a gig in Philly working for the second biggest software developer in the world on their up front website, SAP.com. Before I dive into the limited aspects I can speak about SAP.com's technology I would like to point out the facet of SAP that has had, and will have, a lasting effect on me, the cafateria. These people (SAP) treat their people good! Made to order sushi, made to order Thai, a Philly cheese steak that will challenge South Philly's finest and a Starbucks that feels like it was made just for me, all this within a short walk from my desk. Really, next to the BMW the Germans know how to do it.

Lets dive into my first day. I was sitting at my desk, after enjoying my oh-so-delicious lunch of Alaskan Cod; I hear this loud noise getting louder. Turns out it was a helicopter flying in with the American Co-CEO. As he gets out, much like a scene you might expect to see from Iron Man, he has a dream effect on me. He waves at the people there to greet him and follow's up with a mock gun shot (I can only hope he made the clicking sound that goes with the mock gun shot) at one of the security guards as he steps into the Escalade, in my mind I say YES, awesome! I know right then and there I'm going to love it for my limited time here.

I digress lets talk about a website that needs to address more nations than a senator trying to get votes in NYC. In short, because this is all I will say and feel comfortable, they follow a Model View Presenter (MVP) development process in making their site. SAP's site addresses content based on what nation/region you are coming from all while maintaining a similar look and feel for every end user. Think localization is easy with .Net...not on this scale boys and girls! Now add a level complexity comprising of several teams in more countries than you can count on one hand, developing for this one site. To create a level of consistency across so many sites a template format was built and an engine on top of the .Net engine to address what should be displayed....this is all I will give up, but I can say it's fun and challenging.

Thanks to VML for making this small yet, incredible contract, possible.

loadView vs viewDidLoad

2010-05-09T16:55:43.924-07:00

The Problem:
I was getting a white screen with no data in a UITableView on it in the iPhone simulator.

The Solution:
I had my initialization code for the array in the the "loadView" method and not the "viewDidLoad" method

Explanation:
Don't read self.view in -loadView. Only set it, don't get it. The self.view property accessor calls -loadView if the view isn't currently loaded. There's your infinite recursion. I'm guessing UITableView calls a View [pretty good guess since "view" is in the name. :)] which in turn caused my recursion.

This was a stupid little error that caused me about 30 minutes of my life due to the fact I didn't get any build errors. A simple copy and paste moved me forward.

Update: I think it might be important to distinguish the differece between loadView and viewDidLoad. (below)

loadView is the method in UIViewController that will actually load up the view and assign it to the "view" property. This is also the location that a subclass of UIViewController would override if you wanted to programatically set up the "view" property. viewDidLoad is the method that is called once the view has been loaded. This is called after loadView is called. It is a place where you can override and insert code that does further initial setup of the view once it has been loaded.

Mission Repair -- Getting all things Apple repaired outside of the Apple store.

2010-04-23T19:48:33.971-07:00

Last night around 3:30am I was having a little trouble sleeping, consequently I picked up my laptop pulled up the most recent edition of Diggnation and hoped the wonderful drunk-tech humor would push me off to a restful sleep land. It worked! Then disaster struck, as I was closing the laptop on my night stand, the laptop fell off. In slow motion I watched my laptop hit the ground and the backlight on the monitor break. Damn, I’m more tired than disappointed; I’ll address it in the morning.

I woke up in the morning hoping the laptop would have somehow healed itself. It didn’t. Apple store here I come. $1200 bucks, ahhh no thank you, any other solutions I ask the genius dude. He gently says, yes, Mission Repair. Doing a little research I find them online, engadget has recognized these guys! Instantly a legit shop in my mind and they are based in KC, happiness throughout the body, though most of their business is web based mail-ins. I walk in and find out a good amount of their employees are ex-Apple employees. My lapy is in good hands. They quote me $400 for a new glossy screen, a third of the cost of Apple, I asked if they could fix it in the next hour, they replied with a warming, "yup." At this point I want to hug somebody, anybody really. Flash forward 10 minutes and Mission computer says they are out of the glossy screens, they can have some in tomorrow or they will install a mat finish for 100 dollars less, due to the inconvenience, making my total 300. Done Deal. 30 minutes later I walk out with a fully functional screen on my Macbook

I will be working with Mission Repair quite a bit more for my out of warranty repairs.