[jira] [Resolved] (JENA-1428) NPE in Query Builder

["Claude Warren (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/JENA-1428?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Claude Warren resolved JENA-1428.
---------------------------------
       Resolution: Fixed
    Fix Version/s: Jena 3.6.0

Fixed AbstractRewriter to accept null parameter value.
Fixed NodeValueRewriter to call asNode() rather than getNode() on NodeValues.
Added tests.

Maven build passes.

> NPE in Query Builder
> --------------------
>
>                 Key: JENA-1428
>                 URL: https://issues.apache.org/jira/browse/JENA-1428
>             Project: Apache Jena
>          Issue Type: Bug
>          Components: QueryBuilder
>    Affects Versions: Jena 3.4.0
>            Reporter: Claude Warren
>            Assignee: Claude Warren
>             Fix For: Jena 3.6.0
>
>
> As reported by Chris Dollin on users mailing list:
> I was experimenting with the query builder and hit a problem
> when I was attempting to construct an Expr. This example:
> package com.epimorphics.scratch;
> import org.apache.jena.arq.querybuilder.ConstructBuilder;
> import org.apache.jena.sparql.expr.E_GreaterThan;
> import org.apache.jena.sparql.expr.Expr;
> import org.apache.jena.sparql.expr.ExprVar;
> import org.apache.jena.sparql.expr.nodevalue.NodeValueInteger;
> import org.junit.Test;
> public class Example {
>     @Test public void tryBuilding() {
>         ConstructBuilder cb = new ConstructBuilder();
>         Expr x = new NodeValueInteger(1);
>         Expr y = new ExprVar("y");
>         Expr e = new E_GreaterThan(x, y);
>         cb.addFilter(e);
>         System.err.println(cb.buildString());
>     }
> }
> when run fails with a null pointer exception:
> java.lang.NullPointerException
>     at org.apache.jena.arq.querybuilder.rewriters.
> AbstractRewriter.changeNode(AbstractRewriter.java:126)
>     at org.apache.jena.arq.querybuilder.rewriters.NodeValueRewriter.visit(
> NodeValueRewriter.java:64)
>     at org.apache.jena.sparql.expr.nodevalue.NodeValueInteger.
> visit(NodeValueInteger.java:78)
>     at org.apache.jena.arq.querybuilder.rewriters.ExprRewriter.visit(
> ExprRewriter.java:127)
>     at org.apache.jena.sparql.expr.NodeValue.visit(NodeValue.java:1205)
>     at org.apache.jena.arq.querybuilder.rewriters.ExprRewriter.visit(
> ExprRewriter.java:65)
>     at org.apache.jena.sparql.expr.ExprFunction2.visit(
> ExprFunction2.java:109)
>     at org.apache.jena.arq.querybuilder.rewriters.ElementRewriter.visit(
> ElementRewriter.java:70)
>     at org.apache.jena.sparql.syntax.ElementFilter.visit(
> ElementFilter.java:35)
>     at org.apache.jena.arq.querybuilder.rewriters.ElementRewriter.visit(
> ElementRewriter.java:141)
>     at org.apache.jena.sparql.syntax.ElementGroup.visit(
> ElementGroup.java:120)
>     at org.apache.jena.arq.querybuilder.handlers.WhereHandler.addAll(
> WhereHandler.java:81)
>     at org.apache.jena.arq.querybuilder.handlers.HandlerBlock.addAll(
> HandlerBlock.java:218)
>     at org.apache.jena.arq.querybuilder.handlers.HandlerBlock.addAll(
> HandlerBlock.java:245)
>     at org.apache.jena.arq.querybuilder.AbstractQueryBuilder.build(
> AbstractQueryBuilder.java:555)
>     at org.apache.jena.arq.querybuilder.AbstractQueryBuilder.buildString(
> AbstractQueryBuilder.java:522)
>     at com.epimorphics.scratch.Example.tryBuilding(Example.java:20)
>     at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
>     at sun.reflect.NativeMethodAccessorImpl.invoke(
> NativeMethodAccessorImpl.java:62)
>     at sun.reflect.DelegatingMethodAccessorImpl.invoke(
> DelegatingMethodAccessorImpl.java:43)
>     at java.lang.reflect.Method.invoke(Method.java:498)
>     at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(
> FrameworkMethod.java:47)
>     at org.junit.internal.runners.model.ReflectiveCallable.run(
> ReflectiveCallable.java:12)
>     at org.junit.runners.model.FrameworkMethod.invokeExplosively(
> FrameworkMethod.java:44)
>     at org.junit.internal.runners.statements.InvokeMethod.
> evaluate(InvokeMethod.java:17)
>     at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:271)
>     at org.junit.runners.BlockJUnit4ClassRunner.runChild(
> BlockJUnit4ClassRunner.java:70)
>     at org.junit.runners.BlockJUnit4ClassRunner.runChild(
> BlockJUnit4ClassRunner.java:50)
>     at org.junit.runners.ParentRunner$3.run(ParentRunner.java:238)
>     at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:63)
>     at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:236)
>     at org.junit.runners.ParentRunner.access$000(ParentRunner.java:53)
>     at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:229)
>     at org.junit.runners.ParentRunner.run(ParentRunner.java:309)
>     at org.junit.runner.JUnitCore.run(JUnitCore.java:160)
>     at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(
> JUnit4IdeaTestRunner.java:68)
>     at com.intellij.rt.execution.junit.IdeaTestRunner$Repeater.
> startRunnerWithArgs(IdeaTestRunner.java:47)
>     at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(
> JUnitStarter.java:242)
>     at com.intellij.rt.execution.junit.JUnitStarter.main(
> JUnitStarter.java:70)
> Replacing the addFilter line with
>     cb.addFilter("1 > ?y");
> does not fail, terminating with the expected print-out
> of a construct query
>    CONSTRUCT
>     {
>     }
>   WHERE
>     { FILTER ( 1 > ?y )}
> I tried poking around with the debugger but couldn't see anyhting
> obvious. However, /sometimes/ stepping through the code
> results in it working and sometimes not, presumably depending
> on exactly when I give up through-stepping.
> Am I doing anything obviously wrong (like misunderstanding
> how to use the Expr functionality) or should I file a JIRA?
> This is Jena 3.4.0.



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