STRUTS/JSTL: Need Match \ Equals tag that compares multiple values

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groovyjman21@gmail.com - 23 Apr 2007 23:02 GMT

Hi all,

Struts 1.3.8 Websphere 5.1 web app, wondering how to test my
Customer bean properties in my JSP against multiple values.

I have a business rule which reads "If (the customer is from AZ,
CA, MS, NE, or WA), and (either their total sales or total credits are
greater than zero) then display the following paragraph."

Pseudocodishly:

if((customer.state == AZ || customer.state == CA || customer.state ==
MS || customer.state == NE || customer.state == WA) &&
(customer.totalsales > 0 || customer.totalcredits > 0){
showParagraph;
}

I can't find an efficient way to do this with struts as the equals and
match tags only take one value at a time. I have read that JSTL might
be a way to do this (ie <c:if test = ${...}>) but can't find
sufficient documentation Any help greatly appreciated.

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Richard Senior - 24 Apr 2007 09:01 GMT

> I have a business rule which reads "If (the customer is from AZ,
> CA, MS, NE, or WA), and (either their total sales or total credits are
> greater than zero) then display the following paragraph."

...

> I can't find an efficient way to do this with struts as the equals and
> match tags only take one value at a time. I have read that JSTL might
> be a way to do this (ie <c:if test = ${...}>) but can't find
> sufficient documentation Any help greatly appreciated.

The nearest you would get would be the choose tag in JSTL. See
http://java.sun.com/j2ee/1.4/docs/tutorial/doc/JSTL4.html#wp74001

BUT if this is a business rule, it should be implemented in your
business layer rather than in your presentation layer.

Looking at your description I can't see what "location in (AZ, CA, MS,
NE, WA) and (sales > 0 or credits > 0)" means from a business logic
point of view. You'd probably comment it in your JSP.

For the sake of argument, lets say it means it's an "important"
customer. If you gave your customer bean a method like this:

    public boolean isImportant() {
        return ("AZ".equals(location) || ...
    }

You get to (a) code your logic in Java, (b) keep your business logic in
the model where it belongs, (c) re-use your logic elsewhere and (d)
create a much more readable view:

    <c:if test="${customer.important}">
    ... do something important!
    </c:if>

Regards,

Richard

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STRUTS/JSTL: Need Match \ Equals tag that compares multiple values

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