OPENJPA-1225: Fail fast on wrong constructor() argument

git-svn-id: https://svn.apache.org/repos/asf/openjpa/trunk@808513 13f79535-47bb-0310-9956-ffa450edef68

openjpa-persistence-jdbc/src/test/java/org/apache/openjpa/persistence/criteria/results/TestMultiselect.java

@@ -379,6 +379,26 @@ public class TestMultiselect extends CriteriaTest {
         assertEquals(String.class, tuple4.get(0).getClass());
     }
     
+    public void testConstructorFailsFast() {
+        CriteriaQuery<Tuple> q = cb.createQuery(Tuple.class);
+        Root<Foo> foo = q.from(Foo.class);
+        try {
+            q.multiselect(cb.construct(Foo.class, foo.get(Foo_.flong)));
+            fail("Expected IllegalArgumentException becuase Foo(long) is not a valid constructor");
+        } catch (IllegalArgumentException e) {
+            // good -- but print the error message to check it is informative enough
+            System.err.println(e);
+        }
+        try {
+            q.multiselect(cb.construct(Foo.class));
+            fail("Expected IllegalArgumentException becuase Foo() is not a valid constructor");
+        } catch (IllegalArgumentException e) {
+            // good -- but print the error message to check it is informative enough
+            System.err.println(e);
+        }
+        
+    }
+    
 // =============== assertions by result types ========================
     
     void assertResult(CriteriaQuery<?> q, Class<?> resultClass) {

openjpa-persistence/src/main/java/org/apache/openjpa/persistence/criteria/CompoundSelections.java

@@ -18,6 +18,7 @@
  */
 package org.apache.openjpa.persistence.criteria;
 
+import java.lang.reflect.Constructor;
 import java.util.Arrays;
 import java.util.Collections;
 import java.util.List;
@@ -30,6 +31,7 @@ import javax.persistence.criteria.Selection;
 
 import org.apache.openjpa.kernel.FillStrategy;
 import org.apache.openjpa.kernel.ResultShape;
+import org.apache.openjpa.lib.util.Localizer;
 import org.apache.openjpa.persistence.TupleFactory;
 import org.apache.openjpa.persistence.TupleImpl;
 
@@ -42,6 +44,7 @@ import org.apache.openjpa.persistence.TupleImpl;
  *
  */
 public class CompoundSelections {
+    private static Localizer _loc = Localizer.forPackage(CompoundSelections.class);
     /**
      * Gets the strategy to fill a given compound selection.
      * 
@@ -118,12 +121,29 @@ public class CompoundSelections {
      * @param <X> type of the constructed instance
      */
     public static class NewInstance<X> extends CompoundSelectionImpl<X> {
+        private FillStrategy.NewInstance<X> strategy;
         public NewInstance(Class<X> cls, Selection<?>... selections) {
             super(cls, selections);
+            strategy = new FillStrategy.NewInstance<X>(findConstructor(cls, selections));
         }
         
         public FillStrategy<X> getFillStrategy() {
-            return new FillStrategy.NewInstance<X>(getJavaType());
+            return strategy;
+        }
+        
+        private Constructor<X> findConstructor(Class<X> cls, Selection<?>... selections) {
+            Class<?>[] types = selections == null ? null : new Class[selections.length];
+            if (selections != null) {
+                for (int i = 0; i < selections.length; i++) {
+                    types[i] = selections[i].getJavaType();
+                }
+            }
+            try {
+                return cls.getConstructor(types);
+            } catch (NoSuchMethodException e) {
+                throw new IllegalArgumentException(_loc.get("select-no-ctor", cls, 
+                    types == null ? "[]" : Arrays.toString(types)).getMessage());
+            }
         }
     }
     

openjpa-persistence/src/main/resources/org/apache/openjpa/persistence/criteria/localizer.properties

@@ -21,4 +21,7 @@ root-undefined: No root is defined for criteria query. \
 	Use CriteriaQuery.from(Class) to define a root.
 select-undefined: No terms is selected for criteria query. \
 	Use	CriteriaQuery.select() or multiselect() to select \
-	projection terms for the query.
+	projection terms for the query.
+select-no-ctor: You have specified selection term to construct an instance of \
+	"{0}" with argument types "{1}". But "{0}" has no constructor with such \
+	argument types.