c# Object obj's value is {}. What is "{}"?

Question

I'm using some old code that runs a sql query as a reference.

At some point, it gets to something like:

sqlDataAdapter.Fill(dataSet);
DataRow dataRow = dataSet.Tables[0].Rows[0];
Object obj = dataRow[fieldName];

The old code does:

string output;
if (!string.IsNullOrEmpty(obj.ToString())) { output = obj.ToString(); }
else { output = "Not Available"; }

I changed them to:

output = obj as string ?? "Not Available"

But sometimes, it broke. As I suspected, it was happening breaking when the entry was an int. Casting as an int in those cases solved that problem.

Then another problem arose when there was no entry for obj[fieldName] of type int. When I stepped through the debugger, I was surprised to find that obj wasn't null. In VS, mousing over revealed it had a value {}.

What the heck is {}? How do I make a boolean test of it?

(In the old code, it appears .ToString() returns "" in this case and works as expected.)

Answer 1

{ and } are opening and closing braces and symbolic of the start and finish of an object. Hence an empty object with no special properties is depicted in shorthand as {}. The debugger uses this notation to help you visually distinguish between an empty object, an empty string and null.

If you hover over obj[fieldName] and there is no entry for fieldName, the debugger won't care about that, it'll show the value of obj. You'll have to use the immediate window or a watch/quickwatch. The debugger will only see you hovering over obj and assume you're referring to the array itself, not the contents of the array at the specified index.