[jira] [Created] (WW-4138) OgnlTextParser contains a NPE when the expression is passed in as null

[David Greene (JIRA)]

David Greene created WW-4138:
--------------------------------

             Summary: OgnlTextParser contains a NPE when the expression is 
passed in as null
                 Key: WW-4138
                 URL: https://issues.apache.org/jira/browse/WW-4138
             Project: Struts 2
          Issue Type: Bug
    Affects Versions: 2.3.15
            Reporter: David Greene


Unfortunately, I haven't figured out the exact cause of the issue; however, the 
fix provided brings our system back to how it used to work.


When expression is passed in a null, a NPE is thrown @:

int start = expression.indexOf(lookupChars, pos);

{code}
        Object result = expression;
        int pos = 0;

        for (char open : openChars) {
            int loopCount = 1;
            //this creates an implicit StringBuffer and shouldn't be used in 
the inner loop
            final String lookupChars = open + "{";

            while (true) {
                int start = expression.indexOf(lookupChars, pos);
                if (start == -1) {
                    loopCount++;
                    start = expression.indexOf(lookupChars);
                }
{code}

Here is the fix I'm using in a locally built class file:

{code}
        Object result = expression = (expression == null) ? "" : expression;
        int pos = 0;

        for (char open : openChars) {
            int loopCount = 1;
            //this creates an implicit StringBuffer and shouldn't be used in 
the inner loop
            final String lookupChars = open + "{";

            while (true) {
                int start = expression.indexOf(lookupChars, pos);
                if (start == -1) {
                    loopCount++;
                    start = expression.indexOf(lookupChars);
                }
{code}

I can see about 10 different ways to 'fix' the issue, but this keeps the change 
to a single line since I don't entirely understand the workflow of what's going 
on.

FYI, it seems to have something to do with validate="true" on the form and when 
there are fields to validate which have nested getters, aka:

<@s.hidden key="myFakePatternHolder.pattern.id"/>


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