Some weird behaviour with SharePoint column types, and the data you get by looking at the SPListItem.properties hash.

So, I’ve got a document library, and I’ve added 3 extra columns to it. For simplicity, I shall call them ‘Text’, ‘Number’ and ‘CheckBox’. I filled in some data for them – a number in the Text field, the same number in the number field, and I check the checkbox for all of the items. I end up with a list looking like below…

So, for now, let’s ignore the fact that the value for some of the longer numbers has been rounded in one of the fields – and not ask why MOSS didn’t just complain that the numbers were too big. Instead, let’s ask what the column types being used are…

Consider the following code:
StreamWriter sw = new StreamWriter("output.txt",false);

foreach (SPListItem i in myCollection)
{
sw.Write(i.Name);
foreach (DictionaryEntry h in i.Properties)
{
if (h.Key.ToString().StartsWith("Title") ||
h.Key.ToString().StartsWith("Tex") ||
h.Key.ToString().StartsWith("Yes") ||
h.Key.ToString().StartsWith("Num"))
{
sw.Write(" {0} = {1} ({2})",
h.Key.ToString(),
h.Value.ToString(),
h.Value.GetType().ToString());
}
}
sw.WriteLine();
}
sw.Close();
So, what did this produce? Well, I’ve changed the output to align into columns…

b2b2b2 01.xls Text = 65534             (Int32)  YesNo = 1    (Int32)  Number = 65534.0000000000  (String)
b2b2b2 03.xls Text = 65540             (Int32)  YesNo = 1    (Int32)  Number = 65540.0000000000  (String)
b2b2b2 05.doc Text = 131070            (Int32)  YesNo = 1    (Int32)  Number = 131070.000000000  (String)
b2b2b2 06.xls Text = 131080            (Int32)  YesNo = 1    (Int32)  Number = 131080.000000000  (String)
b2b2b2 07.xls Text = 9999999999999998  (String) YesNo = 1    (Int32)  Number = 9999999999999990  (String)
b2b2b2 09.doc Text = 9999999999999999  (String) YesNo = 1    (Int32)  Number = 9999999999999990  (String)
b2b2b2 12.TIF Text = 10000000000000000 (String) YesNo = true (String) Number = 10000000000000000 (String)
b2b2b2 17.doc Text = 2342345245        (String) YesNo = 1    (Int32)  Number = 2342345245.00000  (String)
b2b2b2 20.doc Text = 4353455656563     (String) YesNo = 1    (Int32)  Number = 4353455656563.00  (String)
c3c3c3 03.jpg Text = 2147483646        (String) YesNo = true (String) Number = 2147483646.00000  (String)
c3c3c3 10.pdf Text = 2147483650        (String) YesNo = true (String) Number = 2147483650.00000  (String)
c3c3c3 17.txt Text = 4294967294        (String) YesNo = true (String) Number = 4294967294.00000  (String)
c3c3c3 18.txt Text = 4294967298        (String) YesNo = true (String) Number = 4294967298.00000  (String)

Hello? The checkbox is sometimes ‘true’, and 1? String or Int32? WTF? Or that the Text column stores 65534 as an Int32, and the Number field as a String? Okay, I can see why the last one might make sense, but why is the TEXT column a number? And what if I now want to assign a String to it? I tried…

i.properties['Text'] = "Hello World";

Guess what – exception (SPInvalidPropertyException, to be precise). But maybe, just maybe, I knew I’d be putting text in there later and that was why I made it an effing text column. And why is the Boolean column an Int or a string? I mean, either is a fine choice, but not BOTH.

Don’t get this. Pissed off. Am going home.