problems with Tomcat 7

[Robert Jäschke]

When running BibSonomy on a Tomcat 7 we very frequently get the following exception:

Caused by: javax.servlet.jsp.JspException: javax.servlet.jsp.JspException: javax.el.ELException: Error invoking function 'mtl:encodeURI'
        at org.apache.jsp.tag.webresources.bibtexs_tagx$Helper.invoke(bibtexs_tagx.java:575)
        at org.apache.jsp.tag.webresources.common.list_tagx$Helper.invoke1(list_tagx.java:710)
        at org.apache.jsp.tag.webresources.common.list_tagx$Helper.invoke(list_tagx.java:751)
        ... 136 more
Caused by: javax.servlet.jsp.JspException: javax.el.ELException: Error invoking function 'mtl:encodeURI'
        at org.apache.jsp.tag.webresources.bibtex.actions_tagx.doTag(actions_tagx.java:216)
        at org.apache.jsp.tag.webresources.bibtexs_tagx._jspx_meth_bib_005factions_005f0(bibtexs_tagx.java:477)
        at org.apache.jsp.tag.webresources.bibtexs_tagx.access$2(bibtexs_tagx.java:463)
        at org.apache.jsp.tag.webresources.bibtexs_tagx$Helper.invoke2(bibtexs_tagx.java:525)
        at org.apache.jsp.tag.webresources.bibtexs_tagx$Helper.invoke(bibtexs_tagx.java:561)
Caused by: javax.el.ELException: Error invoking function 'mtl:encodeURI'
        at de.odysseus.el.tree.impl.ast.AstFunction.eval(AstFunction.java:51)
        at de.odysseus.el.tree.impl.ast.AstEval.eval(AstEval.java:42)
        at de.odysseus.el.tree.impl.ast.AstComposite.eval(AstComposite.java:35)
        at de.odysseus.el.tree.impl.ast.AstNode.getValue(AstNode.java:28)
        at de.odysseus.el.TreeValueExpression.getValue(TreeValueExpression.java:121)
        at org.apache.jasper.runtime.PageContextImpl.proprietaryEvaluate(PageContextImpl.java:1026)
        at org.apache.jsp.tag.webresources.bibtex.actions_tagx._jspx_meth_c_005fwhen_005f8(actions_tagx.java:2289)
        at org.apache.jsp.tag.webresources.bibtex.actions_tagx._jspx_meth_c_005fchoose_005f8(actions_tagx.java:2258)
        at org.apache.jsp.tag.webresources.bibtex.actions_tagx._jspx_meth_c_005fif_005f8(actions_tagx.java:2062)
        at org.apache.jsp.tag.webresources.bibtex.actions_tagx.doTag(actions_tagx.java:201)
        ... 142 more
Caused by: java.lang.NullPointerException

[Former user]

Invoking mtl:encodeURI, a NullPointerException may be thrown, if the argument is the return of another function call; for example (tags/resources/bibtex/actions.tagx:206):

${mtl:encodeURI(mtl:extractDOI(post.resource.miscFields['doi']))}

When the doi is invalid, the return of mtl:extractDOI is empty and mtl:encodeURI fails. This could be void using

<c:when test="${[...] and not empty mtl:extractDOI(post.resource.miscFields['doi'])}">

However, these has to be done for each call to encodeURI with nested function call.

[Daniel Zoller]

Why not intercept the null pointer exception by a null check in Functions#encodeURI?

[Former user]

Seems to be too obvious... By the way, why does the extractDOI return a NullPointer, if there is no DOI? Should rather return an empty string, shouldn't it?

[Robert Jäschke]

It would be better to return NULL. Talk to Daniel. ;-)

[Former user]

avoid NullPointerException using Functions#encodeURI, Functions#decodeURI, and Functions#removeInvalidXmlChars (fixed Issue #38).

→ <<cset 3835ba99d1c5>>