Advanced Forms Handling in Struts 1.1
by Keld H. Hansen
Introduction
This article is about the more advanced features Jakarta Struts
offers in building HTML forms. If you know how to create forms
in plain HTML then the step to building simple forms in Struts
with, for example, a couple of input text fields, a checkbox or
a radio button is not very complicated. When it comes to the
more complex controls like the multi-valued selection list or a
variable length list of input fields it gets more challenging.
This is especially true when the possible selections are not
fixed, but taken from some external source like a database
instead. I've too often found myself struggling with the syntax
and semantics of the HTML-tags when the forms get complex, and
if you search the web for advice, you'll soon see that you have
to collect information from many sources.
In this article I've tried to collect solutions to the most
common non-trivial cases. Every case, of course, is not covered
here. Remember to also read Struts' own documentation, starting
with the documentation for the HTML-tags. You might
find what you need there.
At the end of the article is a table with an overview of the
solutions. I'm sure you'll find it useful when coding your
Struts applications.
Here's a link to a zip file containing all
the examples shown in the article.
The controls in a form
Here is a list of the most commonly used input controls:
| Type |
Look |
Values |
| 1. Text field |
 |
Anything that can be typed in.
One line |
| 2. Text area field |
 |
Anything that can be typed in.
Several lines. |
| 3. Checkbox |
 |
1 of 2 (yes/no - on/off) |
| 4. Radio button |
 |
1 of many fixed values |
5. Selection list -
single type |
 |
1 of many fixed values.
Gives you the same functionality as the radio buttons, only the presentation
differs.
|
6. Selection list -
multiple type |
 |
Several of many fixed values |
| 7. List of checkboxes |
 |
Several of many fixed values.
Gives you the same functionality as the multi selection list, only the
presentation differs. |
In Struts you define a control with a tag from Struts' HTML-
library. The next table shows how these are mapped to the old,
well-known HTML tags:
| Type |
Struts html-tag |
HTML tag |
| 1. Text field |
<html:text property="firstname"/> |
<input type="text" name="firstname"> |
| 2. Text area field |
<html:textarea property="address"/> |
<textarea name="address"> |
| 3. Checkbox |
<html:checkbox property="married" value="yes"/> |
<input type="checkbox" name="married"
value="yes"> |
| 4. Radio button |
<html:radio property="card"
value="Diners"/> . . . |
<input type="radio" name="card"
value="Diners"> . . . |
5. Selection list -
single type |
<html:select property="country"> and
<html:option value="F"/> . . . |
<select name="country">
<option value="F"> . . . |
6. Selection list -
multiple type |
<html:select property="food" multiple="true"> and
<html:option value="milk"/> . . . |
<select name="food" multiple>
<option value="milk"> . . . |
| 7. List of checkboxes |
<html:multibox property="site">
. . . |
<input type="checkbox" name="site"
value="jb">
<input type="checkbox" name="site" value="oj">
. . . |
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