From ffb59c35fcd7b8d6adf658bc794bcaff465ced32 Mon Sep 17 00:00:00 2001
From: Pinaki Poddar <ppoddar@apache.org>
Date: Mon, 11 Aug 2008 17:18:31 +0000
Subject: [PATCH] OPENJPA-692: Detect orphaning relation and change row update
 to delete for join table entry.

git-svn-id: https://svn.apache.org/repos/asf/openjpa/trunk@684822 13f79535-47bb-0310-9956-ffa450edef68
---
 .../openjpa/jdbc/meta/FieldMapping.java       | 53 +++++++++++++++++--
 .../meta/strats/RelationFieldStrategy.java    |  5 +-
 .../bidi/TestBiDirectionalJoinTable.java      | 15 ++++++
 3 files changed, 69 insertions(+), 4 deletions(-)

diff --git a/openjpa-jdbc/src/main/java/org/apache/openjpa/jdbc/meta/FieldMapping.java b/openjpa-jdbc/src/main/java/org/apache/openjpa/jdbc/meta/FieldMapping.java
index 72095a826..3a532f77f 100644
--- a/openjpa-jdbc/src/main/java/org/apache/openjpa/jdbc/meta/FieldMapping.java
+++ b/openjpa-jdbc/src/main/java/org/apache/openjpa/jdbc/meta/FieldMapping.java
@@ -73,6 +73,7 @@ public class FieldMapping
     private int _fetchMode = Integer.MAX_VALUE;
     private Unique[] _joinTableUniques; // Unique constraints on JoinTable
     private Boolean _bidirectionalJoinTableOwner = null;
+    private Boolean _bidirectionalJoinTableNonOwner = null;
     
     /**
      * Constructor.
@@ -1075,10 +1076,10 @@ public class FieldMapping
         ClassMapping relType = elem.getDeclaredTypeMapping();
         if (relType == null) 
         	return false;
-        FieldMetaData[] relFmds = relType.getFields();
+        FieldMapping[] relFmds = relType.getFieldMappings();
         for (int i=0; i<relFmds.length;i++) {
-            if (relFmds[i].getDeclaredTypeMetaData() == getDeclaringMapping()) {
-                FieldMapping rfm = (FieldMapping)relFmds[i];
+            FieldMapping rfm = relFmds[i];
+            if (rfm.getDeclaredTypeMetaData() == getDeclaringMapping()) {
         		ForeignKey rjfk = rfm.getJoinForeignKey();
         		if (rjfk == null) 
         		    continue;
@@ -1086,9 +1087,55 @@ public class FieldMapping
         		 && jfk.getTable().getColumns().length 
         		 == jfk.getColumns().length + rjfk.getColumns().length) {
         			_bidirectionalJoinTableOwner = true;
+        			break;
         		}
         	}
         }
         return _bidirectionalJoinTableOwner.booleanValue();
     }
+    
+    /**
+     * Affirms if this field is the non-owning side of a bidirectional relation
+     * with a join table. Evaluated only once and the result cached for 
+     * subsequent call. Hence must be called after resolution.
+     */
+    public boolean isBidirectionalJoinTableMappingNonOwner() {
+    	if (_bidirectionalJoinTableNonOwner != null)
+    		return _bidirectionalJoinTableNonOwner.booleanValue();
+    	
+    	_bidirectionalJoinTableNonOwner = false;
+        ForeignKey fk = getForeignKey();
+        if (fk == null) 
+        	return false;
+        ForeignKey jfk = getJoinForeignKey();
+        if (jfk == null) 
+        	return false;
+        FieldMapping mappedBy = getValueMappedByMapping();
+        if (mappedBy != null) 
+        	return false;
+        ValueMapping elem = getElementMapping();
+        if (elem == null) 
+        	return false;
+        ClassMapping relType = getDeclaredTypeMapping();
+        if (relType == null) 
+        	return false;
+        FieldMapping[] relFmds = relType.getFieldMappings();
+        for (int i=0; i<relFmds.length;i++) {
+            FieldMapping rfm = relFmds[i];
+            ValueMapping relem = rfm.getElementMapping();
+            if (relem != null && relem.getDeclaredTypeMapping() == getDeclaringMapping()) {
+        		ForeignKey rjfk = rfm.getJoinForeignKey();
+        		if (rjfk == null) 
+        		    continue;
+        		if (rjfk.getTable() == jfk.getTable()
+        		 && jfk.getTable().getColumns().length 
+        		 == jfk.getColumns().length + rjfk.getColumns().length) {
+        			_bidirectionalJoinTableNonOwner = true;
+        			break;
+        		}
+        	}
+        }
+        return _bidirectionalJoinTableNonOwner.booleanValue();
+    }
+
 }
diff --git a/openjpa-jdbc/src/main/java/org/apache/openjpa/jdbc/meta/strats/RelationFieldStrategy.java b/openjpa-jdbc/src/main/java/org/apache/openjpa/jdbc/meta/strats/RelationFieldStrategy.java
index e83db10f8..523267496 100644
--- a/openjpa-jdbc/src/main/java/org/apache/openjpa/jdbc/meta/strats/RelationFieldStrategy.java
+++ b/openjpa-jdbc/src/main/java/org/apache/openjpa/jdbc/meta/strats/RelationFieldStrategy.java
@@ -230,7 +230,10 @@ public class RelationFieldStrategy
             nullInverse(sm, rm);
             updateInverse(sm, rel, store, rm);
         } else {
-            Row row = field.getRow(sm, store, rm, Row.ACTION_UPDATE);
+        	int action = (rel == null 
+        			&& field.isBidirectionalJoinTableMappingNonOwner()) ?
+        					Row.ACTION_DELETE : Row.ACTION_UPDATE;
+            Row row = field.getRow(sm, store, rm, action);
             if (row != null)
                 field.setForeignKey(row, rel);
         }
diff --git a/openjpa-persistence-jdbc/src/test/java/org/apache/openjpa/persistence/jdbc/mapping/bidi/TestBiDirectionalJoinTable.java b/openjpa-persistence-jdbc/src/test/java/org/apache/openjpa/persistence/jdbc/mapping/bidi/TestBiDirectionalJoinTable.java
index 9d30eb663..6747667ab 100644
--- a/openjpa-persistence-jdbc/src/test/java/org/apache/openjpa/persistence/jdbc/mapping/bidi/TestBiDirectionalJoinTable.java
+++ b/openjpa-persistence-jdbc/src/test/java/org/apache/openjpa/persistence/jdbc/mapping/bidi/TestBiDirectionalJoinTable.java
@@ -19,6 +19,7 @@
 package org.apache.openjpa.persistence.jdbc.mapping.bidi;
 
 import java.util.Arrays;
+import java.util.Set;
 
 import javax.persistence.EntityManager;
 import javax.persistence.Query;
@@ -125,6 +126,20 @@ public class TestBiDirectionalJoinTable extends SQLListenerTestCase {
 		assertEquals(0, count(Address.class));
 		assertSQL("DELETE FROM .*J_PERSON_ADDRESSES .*");
 	}
+	
+	public void testBreakingRelationCausesDeleteFromJoinTable() {
+		EntityManager em = emf.createEntityManager();
+		Person person = em.find(Person.class, SSN);
+		em.getTransaction().begin();
+		Set<Address> addresses = person.getAddresses();
+		assertFalse(addresses.isEmpty());
+		Address address = addresses.iterator().next();
+		addresses.remove(address);
+		address.setPerson(null);
+		em.getTransaction().commit();
+		
+		assertSQL("DELETE FROM .*J_PERSON_ADDRESSES .*");
+	}
 
 	/**
 	 * Create a Person with given SSN and fixed number of addresses.