Posts Tagged ‘scripting’

If you are luckily enough to work in a Web 2.0 start up, you probably won’t have to deal with too much legacy code. But for the rest of us, we can often find ourselves working with code which can be even decades out of date.

One of the big issues in PHP has been the deprecation of register globals. Of course, this happened quite a long time ago, because the idea of register globals was just plain stupid, but recent versions of PHP (5.3 onwards), will now throw a deprecation error.

So, we need to find a way to turn register globals off.

The end solution is of course to refactor the code so it doesn’t use register globals at all. Anything short of this is going to be a security nightmare, it’s like a ticking time bomb sitting on your server. But until then, there is a way you can emulate it in your PHP code while you work to get rid of it, allowing you to turn the register global settings off.

All you need is something like this in your code.

foreach ($_REQUEST as $key => $val) {
	$$key = $val;
}

This is one of the geeks among you. I’m currently working on a new open source project which uses a series of database models derived from a base model which includes some standard methods and I was having one problem in particular to do with updating data values in an object.

if (
    !$object->setName($d["name"]) ||
    !$object->setSlug($d["slug"]) ||
    !$object->setDateByArray($d["date"]) ||
    !$object->setContent($d["content"])
) {
    $this->setMessage($object->getMessage());
    return false;
}

As you can see, this does an if statement and then runs all the updates – the idea being that if any of them come back as false, it can set the error message and return false to the controller.

This worked as expected but with one problem – as soon as one of them appears false, PHP stops looking at the other conditions in the if statement. This is a problem because it means the user only gets one piece of feedback at a time. Whereas, it would be much better if we could give them all the fields that were wrong at once.

However, this doesn’t seem possible in the above implementation. Even if I switched it round to check that everything is true, and everything must be true, that suffers from the same problem that once something isn’t, PHP will stop checking the conditions.

I considered whether I could implement it using exceptions – putting all the checks inside a try block and then have the update operations throw an exception if they were invalid. I could then catch this exception and add the error to the list of errors. However, this suffers from the same problem – as soon as the first invalid value triggers an exception, the rest of the try block is ignored.

The solution I have eventually come to is this:

$writes = array (
    $object->setName($d["name"]),
    $object->setSlug($d["slug"]),
    $object->setDateByArray($d["date"]),
    $object->setContent($d["content"])
);

if (in_array(false, $writes)) {
    $this->setMessage($object->getMessage());
    return false;
}

All the operations are run, and their values are fed into an array. That way all the checks get run no matter what value they return. I then search the array for any values set to false and if any of them were, I know there has been a error and can flag it up with the user.

This tutorial will show you how to build a simple hit counter. It does not use any SQL or databases; it stores the hits in a text file.

Allou need to create for this script is your ASP file and a text file. In the text file, simply enter the number 0 and save it in the same directory as count.txt. Take a look at the basic source code.

<%@ Language="VBScript" %>
<% Response.Expires= -1
Response.AddHeader "Cache-Control", "no-cache"
Response.AddHeader "Pragma", "no-cache" %>
<%
if Session("ct") = "" then
fp = Server.MapPath("db\count.txt")
Set fs = CreateObject("Scripting.FileSystemObject")
Set a = fs.OpenTextFile(fp)
ct = Clng(a.ReadLine)
ct = ct + 1
Session("ct") = ct
a.close
Set a = fs.CreateTextFile(fp, True)
a.WriteLine(ct)
a.Close
Set a = Nothing
Set fs = Nothing
else
ct = Clng(Session("ct"))
end if 
%>

Now lets break it down into three sections.

<%@ Language="VBScript" %>

This just states that the page is a VB script page.

<% Response.Expires= -1
Response.AddHeader "Cache-Control", "no-cache"
Response.AddHeader "Pragma", "no-cache" %>

This section stops the user refreshing the page to clock up hits.

<%
if Session("ct") = "" then
fp = Server.MapPath("count.txt")
Set fs = CreateObject("Scripting.FileSystemObject")
Set a = fs.OpenTextFile(fp)
ct = Clng(a.ReadLine)
ct = ct + 1
Session("ct") = ct
a.close
Set a = fs.CreateTextFile(fp, True)
a.WriteLine(ct)
a.Close
Set a = Nothing
Set fs = Nothing
else
ct = Clng(Session("ct"))
end if 
%>

This is the main section which adds the hits.

fp = Server.MapPath("count.txt")

This tells the server where to find the file. You can modify the file location by changing count.txt. So for instance if you wanted to to be called hitcounter.txt and in the directory db you would use:

fp = Server.MapPath("db\hitcounter.txt")

All you have to do is alter the file path in the quote marks.

Set fs = CreateObject("Scripting.FileSystemObject")
Set a = fs.OpenTextFile(fp)
ct = Clng(a.ReadLine)

This section opens the file using FileSystemObject and reads the first line. It then sets the variable ct to the amount of hits it has already had.

ct = ct + 1

This line adds one hit to the total number of visitors.

Session("ct") = ct
a.close

This part saves a session variable as the new click through with the new amount of visitors and closes the text file.

Set a = fs.CreateTextFile(fp, True)
a.WriteLine(ct)
a.Close

This code creates a new text file over the old one and adds in the new amount of visitors to it. Then it closes the text file.

Now you have a working hit counter. All you need to do is add the hit counter into your page:

You are a visitor number <%=ct%>!

This would display the amount of visitors. Now to save confusion, here is the full source code for the page:

<%@ Language="VBScript" %>
<% Response.Expires= -1
Response.AddHeader "Cache-Control", "no-cache"
Response.AddHeader "Pragma", "no-cache" %>
<%
if Session("ct") = "" then
fp = Server.MapPath("db\count.txt")
Set fs = CreateObject("Scripting.FileSystemObject")
Set a = fs.OpenTextFile(fp)
ct = Clng(a.ReadLine)
ct = ct + 1
Session("ct") = ct
a.close
Set a = fs.CreateTextFile(fp, True)
a.WriteLine(ct)
a.Close
Set a = Nothing
Set fs = Nothing
else
ct = Clng(Session("ct"))
end if 
%>
<html>
<body>
You are a visitor number <%=ct%>!
</body>
</html>

JavaScript allows you to adding programming functions to your web pages. Browsers will read the HTML and interpret the JavaScript. JavaScript can also produce dynamic effects using variables. JavaScript can also react to events, write HTML code and validate data.

The key parts of JavaScript are functions and events. Functions are mini scripts that can be executed by an event such as a timer or a user clicking on a link. Take a look at this basic script that brings up a gray dialog box saying ‘Yay! javaScript Rules!’

<script language="JavaScript">
<!--

function yay() {
alert('Yay! JavaScript rules!');
}

// -->
</script>

The java is in a standard script tag (which you will read about next) and also has comment tags around it. This hides the script from old browsers who don’t understand JavaScript.