[#602] Test and fix for NPE that appears after copying query builder …

…using parameter multiple times in select clause. Fixes #602

CHANGELOG.md

@@ -10,10 +10,12 @@ Not yet released
 
 * Add support for providing entity view optional parameters in spring-data repositories via `@OptionalParam`
 * Introduced `EMBEDDING_VIEW` function as proper replacement for many `OUTER` function uses in entity views
+* Smoothen support for embeddables in updatable entity views
+* Improve performance by omitting null precedence emulation on MySQL for the default null precedence
 
 ### Bug fixes
 
-None
+* Fix for `NullPointerException` that happened during query builder copying when having a parameter multiple times in a select clause
 
 ### Backwards-incompatible changes
 

core/impl/src/main/java/com/blazebit/persistence/impl/ParameterManager.java

@@ -261,9 +261,11 @@ private Integer determinePositionalOffset(String parameterName) {
 
     public void unregisterParameterName(String parameterName, ClauseType clauseType) {
         ParameterImpl<?> parameter = parameters.get(parameterName);
-        parameter.getClauseTypes().remove(clauseType);
-        if (parameter.getClauseTypes().isEmpty()) {
-            parameters.remove(parameterName);
+        if (parameter != null) {
+            parameter.getClauseTypes().remove(clauseType);
+            if (parameter.getClauseTypes().isEmpty()) {
+                parameters.remove(parameterName);
+            }
         }
     }
 

core/impl/src/main/java/com/blazebit/persistence/impl/ParameterRegistrationVisitor.java

@@ -16,6 +16,7 @@
 
 package com.blazebit.persistence.impl;
 
+import com.blazebit.persistence.parser.expression.ArrayExpression;
 import com.blazebit.persistence.parser.expression.ParameterExpression;
 import com.blazebit.persistence.parser.expression.VisitorAdapter;
 
@@ -28,6 +29,7 @@ public class ParameterRegistrationVisitor extends VisitorAdapter {
 
     private final ParameterManager parameterManager;
     private ClauseType clauseType;
+    private ClauseType secondClauseType;
 
     public ParameterRegistrationVisitor(ParameterManager parameterManager) {
         this.parameterManager = parameterManager;
@@ -40,9 +42,22 @@ public void visit(ParameterExpression expression) {
             throw new IllegalArgumentException("The parameter name '" + expression.getName() + "' is reserved - use a different name");
         } else {
             parameterManager.registerParameterName(expression.getName(), expression.isCollectionValued(), clauseType);
+            if (secondClauseType != null) {
+                parameterManager.registerParameterName(expression.getName(), expression.isCollectionValued(), secondClauseType);
+            }
         }
     }
 
+    @Override
+    public void visit(ArrayExpression expression) {
+        expression.getBase().accept(this);
+        // The index will always end up in the on clause
+        ClauseType oldClauseType = secondClauseType;
+        secondClauseType = ClauseType.JOIN;
+        expression.getIndex().accept(this);
+        secondClauseType = oldClauseType;
+    }
+
     public void setClauseType(ClauseType clauseType) {
         this.clauseType = clauseType;
     }

core/testsuite/src/test/java/com/blazebit/persistence/testsuite/QueryBuilderCopyTest.java

@@ -0,0 +1,39 @@
+/*
+ * Copyright 2014 - 2018 Blazebit.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.blazebit.persistence.testsuite;
+
+import com.blazebit.persistence.testsuite.entity.Document;
+import org.junit.Test;
+
+/**
+ * @author Christian Beikov
+ * @since 1.3.0
+ */
+public class QueryBuilderCopyTest extends AbstractCoreTest {
+
+    @Test
+    // Test for issue #602
+    public void testQueryCopying() {
+        // The key to reproducing the bug is having the parameter in the select clause multiple times
+        cbf.create(em, Long.class)
+                .from(Document.class)
+                .select("COALESCE(id,:param3)")
+                .select("COALESCE(id,:param3)")
+                .copy(String.class)
+                .select("name");
+    }
+}