JSP conditional expression in javascript

Question

Please take a look at this javascript code inside a GSP(similar to JSP):

var json =JSON.parse("${savedkpiz.get(0).kpi.replace("\"","\\\"")}")

savedkpiz(list object) object is sometimes have no element so access at 0 will throw NPE, how can i prevent this code from executing?? JavaScript if else seems not working

var json =JSON.parse("${if(savedkpiz.size()>0) ? savedkpiz.get(0).kpi.replace("\"","\\\""):""}")

above code too not working?? how can i put condition on this and at the same time if true then populate json variable.

Please help guyz, thanks in advance

You cannot call methods (other than getters) on elements accessed with ${}. — Sotirios Delimanolis
– Sotirios Delimanolis, Commented Sep 16, 2013 at 12:25
Is the first code working? I don't think so, since you are delimiting the strings with double quotes even inside the string itself, making it end and restart more than once. You should escape the double quotes inside the main string or use single quotes(if allowed). — Niccolò Campolungo
– Niccolò Campolungo, Commented Sep 16, 2013 at 12:25

Ravi K Thapliyal · Accepted Answer · 2013-09-16 14:03:56Z

1

You can split your logic and achieve what you want by using JSTL's <c:if> tag and doing the string substitution in JavaScript instead.

var jsonStr = "";

<c:if test="${not empty savedkpiz}">
    jsonStr = "${savedkpiz[0]}".replace(/"/g, "\\\"");
</c:if>

var json = JSON.parse(jsonStr);

edited Sep 16, 2013 at 14:03

answered Sep 16, 2013 at 13:25

Ravi K Thapliyal

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2 Comments

user1983983 Over a year ago

It would be much simpler to just check for ${not empty savedkpiz}.

Ravi K Thapliyal Over a year ago

@user1983983, that is so much better. Thanks for sharing.

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