In this section we use sessions to improve the user interaction with the
client entry <form> developed in Chapter 6. The
improvements focus on the interaction when the <form> is
submitted and fields don't validate. We modify the scripts to:
Display error messages on the client entry <form>
Use session variables to pass back the submitted fields to the
<form> generation script, saving the user rekeying all
the data to correct the errors
Improving the Client Entry <form>
The client entry <form>, generated by the script shown
in Example 6-7, collects client fields to either create a new client or edit
the details of an existing client. The script shown in Example 6-8 performs
the server-side validation of the client <form> data, and
updates or inserts a row in the customer table if there are no
errors.
If the validation fails, the script shown in Example 6-8 generates a page
to display the errors to the user, and the user then follows a hypertext link
back to the client entry <form> to reenter the fields. The
solution provided by Examples 6-7 and 6-8 suffers three problems:
The user is forced to reenter the entire client entry
<form> from scratch when an error is encountered during
validation
The errors that are encountered during validation are displayed by
Example 6-8 and not the entry <form> where they would be
useful
The error page generated by Example 6-8 isn't safe from the reload
problem described in Chapter 6
In this section we develop the scripts to make use of session variables to
solve these problems. Rather than displaying the error messages on a page
generated by the validation script, we make the necessary changes to display
the errors in red above the appropriate fields on the client entry
<form>, as shown in Figure
8-2.
Both the script that generates the client entry <form>
and the script that validates the data need to be modified to use sessions and
the session variables. Because the validation script processes the fields
collected in the client <form> and generates any associated
errors, we look at the changes required for that script first.
