Expiration Date Calculator
by John Peterson
Some scripts you have to write... others you write because they're interesting
or just plain cool... and finally there are scripts like this... scripts that
don't do much and take longer to write then it would have taken you to just do
what you wrote the script to do!
Let me explain... I'm lazy. (Wow that was easier to explain then I thought!)
No really... we've got this thing called security that we, as a company,
have to worry about. As part of this security thing, it's company policy
that certain passwords get changed on a regular basis. The time period in question
ends up being 45 days. To make matters worse... I can't change my own
password. There really is a good explanation as to why, but it's a long one
and doesn't really pertain to the issue at hand. So anyway... every 45 days
or so I email someone in our services department to assign me a new
(complex and impossible to remember) password. Once I receive and commit
said password to memory, I figure out the date it will expire and write it down
on a Post-it Note
that I stick to the edge of my monitor so I will remember to renew the password
before it expires. (There's nothing like being locked out of your own web server!)
Here's where that lazy thing comes in. (After reading this, you might be inclined
to change that label to crazy, but again I digress.) In order to figure out the
expiration date I could simply look at my calendar and count off 45 days. I
could also say "the heck with it" and figure 42 days is close enough
and simply count off 6 weeks. (For the mathematically challenged: 7 days in a
week times 6 weeks = 42 days). And yet... although I have no idea why it should...
doing either of these simple tasks annoys me. So... we've arrived at the point
of this script which (if you haven't already guessed) is to figure out when my
password is going to expire!
For those of you in the process of looking up the number of the local mental
institution, in my defense, I already had my own custom start page running
on my local web server with a number of little tools already on it.
(FYI: phone message taker, phone number query, router config screens,
forms for my favorite search engines, a page containing dns, ip addresses,
and connection details to all the servers I deal with, and a table of the
links I use on a daily basis). It's my own personal start page. As such...
adding a little expiration date script wasn't a big deal and fits right
in with the way I work.
The UI
By now most of you are probably aware of my great flair for user interface design.
;) Here's a screen cap:
The Code
Nothing really revolutionary here... not even very pretty code, but it does
work so here it is:
<%@ Language="VBScript" %>
<% Option Explicit
Dim datStartDate
Dim intUnitsToAdd
Dim strUnits
datStartDate = Request.QueryString("StartDate")
intUnitsToAdd = Request.QueryString("UnitsToAdd")
strUnits = Request.QueryString("Units")
%>
<html>
<head>
<title>ASP 101's Expiration Date Calculator</title>
</head>
<body>
<!--
Form defaults are hard-wired to the values I need...
I'm too lazy to do the postback work. What'd you expect? ;)
-->
<form action="<%= Request.ServerVariables("URL") %>">
Start Date: <input type="text" name="StartDate" value="<%= Date() %>" />
<br />
Time Interval: <input type="text" name="UnitsToAdd" value="45" />
<select name="Units">
<option value="s">Seconds</option>
<option value="n">Minutes</option>
<option value="h">Hours</option>
<option value="d" selected="true">Days</option>
<option value="ww">Weeks</option>
<option value="m">Months</option>
<option value="yyyy">Years</option>
</select>
<input type="submit" value="Calculate" />
</form>
<%
If strUnits <> "" Then
' I know... bad code... render block and all... it works doesn't it?
%>
<p>
Based on a start date of <%= datStartDate %>
and a time interval of <%= intUnitsToAdd %> <%= strUnits %>,
the expiration date is:
<strong><%= DateAdd(strUnits, intUnitsToAdd, datStartDate) %></strong>
</p>
<%
End If
%>
</body>
</html>
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Download
As usual... here's a zip file if you prefer: expirationdate.zip (around 800 bytes)
Update: ASP.NET Version
I received quite a few responses about the above code and they basically fell into 3 categories:
- Alternate date formats
- Ideas to automate the process more completely (including using Outlook, IIS's SMTP Server, Task Scheduler, etc...)
- An ASP.NET version
The alternate date formats are generally easily to implement and I'll leave them as an exercise for the
reader since no matter what format I use someone won't be happy. In terms of adding code to
more fully automate the process, it's a good idea and I appreciate all the suggestions, but doing
it on the web server is cumbersome and sort of inappropriate to the task at hand
(aka. managing the password to the server) and the alternatives (using Task Scheduler, Outlook scripts,
etc.) sort of fall outside the scope of a site dedicated to ASP. (See... I am lazy... if I can't publish a
script then what's the sense in writing it? ;) )
Anyway... that brings us to
the third item: an ASP.NET version for those of you who have completely switched over to .NET.
Since I couldn't come up with an easy excuse not to write one... here it is.
I've used ASP.NET server controls where appropriate and except for the lack of validation
(which is missing from the original as well) it's not half bad.
Screen Cap
The .NET Code
<%@ Page Language="VB" Trace="False" %>
<script Language="VB" Option="Strict" RunAt="Server">
Sub Page_Load(sender As Object, e As EventArgs)
If Not Page.IsPostBack
' Init Form Values on First Page Load
calStartDate.SelectedDate = DateTime.Now
txtUnitsToAdd.Text = 45
ddlUnits.SelectedIndex = 3
' Hide result label
divResult.Visible = False
End If
End Sub
Sub btnCalculate_Click(sender As Object, e As EventArgs)
Dim datStartTime As DateTime
Dim datEndTime As DateTime
Dim intUnitsToAdd As Integer
' In case you run into trouble...
Trace.Write(calStartDate.SelectedDate)
Trace.Write(txtUnitsToAdd.Text)
Trace.Write(ddlUnits.SelectedItem.Value)
datStartTime = calStartDate.SelectedDate
intUnitsToAdd = txtUnitsToAdd.Text
Select Case ddlUnits.SelectedItem.Text
Case "Seconds"
datEndTime = datStartTime.AddSeconds(intUnitsToAdd)
Case "Minutes"
datEndTime = datStartTime.AddMinutes(intUnitsToAdd)
Case "Hours"
datEndTime = datStartTime.AddHours(intUnitsToAdd)
Case "Days"
datEndTime = datStartTime.AddDays(intUnitsToAdd)
Case "Weeks"
datEndTime = datStartTime.AddDays(intUnitsToAdd * 7)
Case "Months"
datEndTime = datStartTime.AddMonths(intUnitsToAdd)
Case "Years"
datEndTime = datStartTime.AddYears(intUnitsToAdd)
End Select
lblStartDate.Text = datStartTime
lblInterval.Text = intUnitsToAdd & " " & ddlUnits.SelectedItem.Text
lblResult.Text = datEndTime
' Show result label
divResult.Visible = True
End Sub
</script>
<html>
<head>
<title>ASP 101's Expiration Date Calculator</title>
</head>
<body>
<form runat="server">
Start Date:
<asp:Calendar id="calStartDate" runat="server" />
<br />
Time Interval:
<asp:TextBox id="txtUnitsToAdd" runat="server" />
<asp:DropDownList id="ddlUnits" runat="server">
<asp:ListItem>Seconds</asp:ListItem>
<asp:ListItem>Minutes</asp:ListItem>
<asp:ListItem>Hours</asp:ListItem>
<asp:ListItem>Days</asp:ListItem>
<asp:ListItem>Weeks</asp:ListItem>
<asp:ListItem>Months</asp:ListItem>
<asp:ListItem>Years</asp:ListItem>
</asp:DropDownList>
<asp:Button id="btnCalculate" Text="Calculate"
onclick="btnCalculate_Click" runat="server" />
</form>
<div id="divResult" runat="server">
<p>
Based on a start date of
<asp:Label id="lblStartDate" runat="server" />
and a time interval of
<asp:Label id="lblInterval" runat="server" />,
the expiration date is:
<strong><asp:Label id="lblResult" runat="server" /></strong>
</p>
</div>
</body>
</html>
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The .NET Download
And again... here's a zip file if you prefer: expirationdatedotnet.zip (around 1 KB)
