Building An Extensible Form Validator Class - A Quick Snack (
Page 10 of 12 )
At this stage, I think I have enough
building blocks to actually begin using this class to perform form input
validation. Keep in mind, though, that I've been wrong before, and so my initial
feeling of satisfaction may soon disappear.
First, let's build a simple
form:
<html>
<head>
<basefont face="Arial">
</head>
<body>
<form action="processor.php" method="POST">
<b>Name:</b>
<br>
<input type="text" name="name" size="15">
<p>
<b>Age:</b>
<br>
<input type="text" name="age" size="2" maxlength="2">
<p>
<b>Sex:</b>
<br>
<input type="Radio" name="sex" value="m">Male
<input type="Radio" name="sex" value="f">Female
<p>
<b>Favourite sandwich type:</b>
<br>
<select name="stype">
<option value="">-select one-</option>
<option value="1">Thin crust</option>
<option value="2">Thick crust</option>
<option value="3">Toasted</option>
</select>
<p>
<b>Favourite sandwich filling:</b>
<br>
<input type="Checkbox" name="sfill[]" value="BLT">Bacon, lettuce tomato
<input type="Checkbox" name="sfill[]" value="EC">Egg and cheese <input
type="Checkbox" name="sfill[]" value="PBJ">Peanut butter and jelly
<p>
<input type="Submit" name="submit" value="Save">
</form>
</body>
</html>
Here's what it looks like:
Now, when this form is submitted, the PHP script
"processor.php" will take over. This script will first need to verify that the
data entered into the form is acceptable (that's where our newly-minted
FormValidator class comes in) and then do something with it (for example, INSERT
the data into a MySQL database). Take a look:
<?php
// include class
include("FormValidator.class.inc");
// instantiate object
$fv = new FormValidator();
// perform validation
$fv->isEmpty("name", "Please enter a name"); $fv->isNumber("age",
"Please enter a valid age"); $fv->isWithinRange("age", "Please enter an
age within the numeric range 1-99", 1, 99); $fv->isEmpty("sex", "Please
enter your sex"); $fv->isEmpty("stype", "Please select one of the listed
sandwich types"); $fv->isEmpty("sfill", "Please select one or more of
the listed sandwich fillings");
if ($fv->isError())
{
$errors = $fv->getErrorList();
echo "<b>The operation could not be performed because one or
more error(s) occurred.</b> <p> Please resubmit the form after making
the following changes:";
echo "<ul>";
foreach ($errors as $e)
{
echo "<li>" . $e['msg'];
}
echo "</ul>";
}
else
{
// do something useful with the data
echo "Data OK";
}
?>
Let's see if it works. Here's what happens when I submit the
form with no fields filled in:
The operation could not be performed because one or more error(s)
occurred.
Please resubmit the form after making the following changes:
* Please enter a name
* Please enter a valid age
* Please enter an age within the numeric range 1-99
* Please enter your sex
* Please select one of the listed sandwich types
* Please select one or more of the listed sandwich fillings
And here's what happens when I submit the form with incorrect
data in the age field:
The operation could not be performed because one or more error(s)
occurred.
Please resubmit the form after making the following changes:
* Please enter an age within the numeric range 1-99
And here's what happens when I repent, correct all my errors
and submit the form with valid data:
Data OK
