System information

110 Chapter 10: Lesson 7: Validating Data to Enforce Business Rules

Because you did not yet add any logic to test whether any values entered in the form are valid, the

page works precisely as before, displaying a message that indicates the database was updated,

without actually performing the update.

For more information about using the

cfset and cfif tags, see ColdFusion MX Developer’s Guide

or CFML Reference.

Ensuring that a value was entered

The first approach that you take to enforce Compass Travel business rules is to enhance the action

page to validate the data collected on the data entry form. The action page receives a form variable

for every field on the form that contains a value. You use the

cfif tag to test the values of these

fields to ensure that they adhere to Compass Travel business rules.

You can use the

cfif tag to create conditions that evaluate to either True or False. To use the cfif

tag to test whether a trip name was entered (business rule 1) on the Trip Edit form, you add the

following

cfif statement:

<cfoutput> Trip Name cannot be blank. </cfoutput>

</cfif>

In this example, the cfif statement tests to see if the value of the form variable tripName is

blank. If the trip name condition evaluates to True, ColdFusion sends the message "Trip name

cannot be blank" to the browser.

Note: The keyword EQ is an operator that tests for equality. For more information about the cfif tag

and its operators, see ColdFusion MX Developer’s Guide.

To ensure that a Trip Name was entered:

Open the tripeditaction.cfm file.

Enter the following code after the line <cfset isOk = "Yes">.

<cfoutput>Trip name cannot be blank.<br></cfoutput>

</cfif>

Save the file.

To test the data validation:

Open the tripedit.cfm page in a browser.

Verify that there is no value in the Trip Name field.

Click Save.

The error message “Trip name cannot be blank” appears.