System information
Exercise 6: Dynamically populating the list of event types 119
To test the modified code:
1.
View the tripedit.cfm page in a browser.
2.
Test the client- and server-side field validations by filling out the fields on the form and clicking
Save.
Testing recommendations:
■ Omit required fields such as trip name or location.
■ Make the departure date an invalid date, such as 12/32/2002.
■ Enter a nonnumeric value in Number of People, such as one.
Exercise 6: Dynamically populating the list of event types
Currently, the event types in the tripedit.cfm file are hard-coded. In the preceding exercises, each
option tag in the event type contained a value attribute and option text, such as Surfing. These
values come from the eventtypes table; they do not have to be hard-coded. The event type in the
Trips table is an identifier that is used as a foreign key to the eventtypes table, which holds the
actual event names. The eventtypes table column
eventTypeID is used for the value attribute
and the
eventType for the literal value that appears in the select box. To retrieve the data from
this table, you must include the following
cfquery:
<cfquery name="GetEvents" datasource="CompassTravel">
SELECT eventType, eventTypeID
FROM eventtypes
</cfquery>
To exploit the query in the HTML option tags, you can replace the HTML select tag with a
cfselect tag.
The
cfselect tag is an improved version of the HTML select tag. Like other ColdFusion form
tags, the
cfselect tag provides the required and message attributes that validate the data
entered. Using the
cfselect tag and the preceding cfquery, you can implement the eventType
field data entry as follows.
To display a list of event types from the eventtypes table and add validation:
1.
View the tripedit.cfm page in a browser. Select the event types drop-down list. Notice that only
three event types appear in the list.
2.
Open the tripedit.cfm file in the my_app directory.
3.
Add the following code before the <html> tag:
<cfquery name="GetEvents" datasource="CompassTravel">
SELECT eventType, eventTypeID
FROM eventtypes
</cfquery>
Note: In previous exercises, you learned to write structured reusable code by placing queries in
ColdFusion components. Although this practice is advisable when creating ColdFusion
applications, you put the query in the tripedit.cfm file for simplicity.