With actually very little code, I managed to answer a question I've had
for some time: "How can I easily publish the dates my content files were 
last edited?"

Thankfully, we have the FileInfo object in .NET. Instantiating it allows
us to view the metadata associated with files on the server. 

I handled this in two parts: one in a common class accessible by every
Web form, and the other in specific Web forms.

First, the "common" portion:

    Public Shared Function getContentXmlFileDate(ByVal strFilePath As String) As DateTime
        '2010.05.12 I want a function that can be called by any of the _main.aspx's that
        'will return the timestamp on its corresponding XML file.

        'set the return value to datNull by default
        Dim datFile As DateTime = datNull

        Dim myFile As FileInfo = New FileInfo(strFilePath)

        If myFile.Exists Then

            datFile = myFile.LastWriteTime

        End If

        Return datFile

    End Function

Note a reference to a constant called "datNull." It is simply a Date
set to the value "1/1/1900", which is the earliest value Microsoft SQL 
Server would historically allow (in several recent versions). Using
an actual NULL would cause terrible things to happen, so datNull was 
an answer to handling things somewhat gracefully.

So, the code above simply asks for the path of a specific XML file, 
instantiates an object containing its metadata, copies the desired 
datetime into a variable, and returns that value. If the path is 
incorrect (the file cannot be found at that path), the variable is 
returned with it's default value -- datNull.

That bit of code actually did all of the heavy lifting here. The 
remainder is simply a function, local to the Web form, that fills 
in the blanks for the common function:


    Private Function getContentDateString() As String
        '2010.05.12
        'calls common.getContentXmlFileDate()
        Dim strDate As String = String.Empty

        'have to do this here --- there is no Server.MapPath() in common
        Dim datContentDate As DateTime = common.getContentXmlFileDate(Server.MapPath("~/interests.xml"))

        'the source function in common will return datNull if an error occurred.
        'check to make sure we're not returning the default null datetime.

        If datContentDate <> datNull Then
            strDate = datContentDate.ToString()
        End If

        Return strDate
    End Function

Called from the appropriate location in the Web form, this local 
function simply returns that last write date from the common function, 
in string form. It contains (and passes) the path to the appropriate XML 
file and receives the date object back. Next, it compares the value of 
the date object to that of our old friend, datNull. If the two values are 
inequal, it converts that file's date value to a string and returns it.

The string variable that received the return value is checked for length
(The return value is String.Empty by default), and, currently, is 
appended to the page title along with a short string. So, the title
"interests - halfgk.com" becomes "interests - halfgk.com (updated 
5/11/2010 8:46:10 PM)." 

Honestly, I'm not entirely happy with how I've implemented the display
at this point. But I'm thrilled I've got the data coming back from the 
file system on the server. 

(Incidentally, my initial thought was to use JavaScript to plant the
value in the status bar of the browser. In IE 8, this worked flawlessly.
But Firefox users won't see it by default, because the browser must be
configured to allow JavaScript to change the status message. The
capability exists, but it's turned off by default. A simple change to 
the right value in about:config is all that's needed. Of course, you'd
have to have everybody who views your web app make this configuration
change.)

So for now, the value may be found in the "main" web forms of the 
interests, professional and education sections of the site (although
I really only needed it for the interests section -- it usually gets 
updated at least once per week.). Perhaps I'll come up with a better
means of implementation shortly.

That should be it for now! Contact me using the site's contact form if 
you have questions. Feel free to use the code in your projects. A shout
out in your project would be thoughtful. Also, drop me a line and let me
know how you might have tweaked things to better suit your needs. 
Finally, I wouldn't profess to be THE expert on matters represented in
my code -- so drop me a line if you have constructive suggestions, too. 
I'd like to hear from you!
  

Best,

halfgk


copyright 2010 halfgk.com