JAVA-812: Only set $readPreference on a query if the read preference is not primary.

This lets the slaveOK bit have precedence if it's set.

Author: jyemin

src/main/com/mongodb/DBCollection.java

@@ -722,7 +722,7 @@ public DBObject findOne( DBObject o, DBObject fields, DBObject orderBy, ReadPref
         QueryOpBuilder queryOpBuilder = new QueryOpBuilder().addQuery(o).addOrderBy(orderBy);
 
         if (getDB().getMongo().isMongosConnection()) {
-            queryOpBuilder.addReadPreference(readPref.toDBObject());
+            queryOpBuilder.addReadPreference(readPref);
         }
 
         Iterator<DBObject> i = __find(queryOpBuilder.get(), fields , 0 , -1 , 0, getOptions(), readPref, getDecoder() );

src/main/com/mongodb/DBCursor.java

@@ -362,7 +362,7 @@ private void _check() {
                 .addSpecialFields(_specialFields);
 
         if (_collection.getDB().getMongo().isMongosConnection()) {
-            builder.addReadPreference(_readPref.toDBObject());
+            builder.addReadPreference(_readPref);
         }
 
         _it = _collection.__find(builder.get(), _keysWanted, _skip, _batchSize, _limit,

src/main/com/mongodb/QueryOpBuilder.java

@@ -13,7 +13,7 @@ class QueryOpBuilder {
 	private String hintStr;
 	private boolean explain;
 	private boolean snapshot;
-	private DBObject readPref;
+	private ReadPreference readPref;
 
 	private DBObject specialFields;
 
@@ -93,16 +93,17 @@ public QueryOpBuilder addSnapshot(boolean snapshot){
 	}
 
     /**
-     * Adds ReadPreference to the operation
-     * @param readPref
-     * @return
+     * Adds a read preference to the query operation
+     *
+     * @param readPref the read preference
+     * @return this
      */
-    public QueryOpBuilder addReadPreference(DBObject readPref){
+    public QueryOpBuilder addReadPreference(ReadPreference readPref) {
         this.readPref = readPref;
         return this;
     }
-	
-	/**
+
+    /**
 	 * Constructs the query operation DBObject
 	 * @return DBObject representing the query command to be sent to server
 	 */
@@ -128,8 +129,8 @@ public DBObject get() {
                     queryop.put("$explain", true);
                 if (snapshot)
                     queryop.put("$snapshot", true);
-                if (readPref != null)
-                    queryop.put(READ_PREFERENCE_META_OPERATOR, readPref);
+                if (readPref != null && readPref != ReadPreference.primary())
+                    queryop.put(READ_PREFERENCE_META_OPERATOR, readPref.toDBObject());
 
                 return queryop;
             }

src/test/com/mongodb/QueryOpTest.java

@@ -4,70 +4,80 @@
 import org.testng.annotations.*;
 
 /**
- * Test that QueryOpBuilder creates query operations that abide by 
- * @author stevebriskin
+ * Test that QueryOpBuilder creates query operations that abide by
  *
+ * @author stevebriskin
  */
-public class QueryOpTest extends TestCase{
-	
-	@Test
-	public void testQueryOnly(){
-		DBObject query = QueryBuilder.start("x").greaterThan(1).get();
-		DBObject obj = new QueryOpBuilder().addQuery(QueryBuilder.start("x").greaterThan(1).get()).get();
-		assertEquals(query, obj);
-		
-		assertNotNull(new QueryOpBuilder().get());
-		
-	}
-	
-	@Test
-	public void testQueryAndOthers(){
-		DBObject query = QueryBuilder.start("x").greaterThan(1).get();
-		DBObject orderBy = new BasicDBObject("x", 1);
-		DBObject hintObj = new BasicDBObject("x_i", 1);
-		DBObject readPref = new BasicDBObject("$readPreference",ReadPreference.primary().toDBObject());
-		String hintStr = "y_i";
-		
-		
-		DBObject queryOp = new QueryOpBuilder().addQuery(query).addOrderBy(orderBy).addHint(hintStr).get();
-		assertEquals(queryOp.get("$query"), query);
-		assertEquals(queryOp.get("$orderby"), orderBy);
-		assertEquals(queryOp.get("$hint"), hintStr);
-		assertNull(queryOp.get("$explain"));
-		assertNull(queryOp.get("$snapshot"));
-		
-		//orderby should only be there if added
-		queryOp = new QueryOpBuilder().addQuery(query).addHint(hintStr).get();
-		assertEquals(queryOp.get("$query"), query);
-		assertNull(queryOp.get("$orderby"));
-		
-		//hintObj takes precedence over hintStr
-		queryOp = new QueryOpBuilder().addQuery(query).addOrderBy(orderBy).addHint(hintStr).addHint(hintObj).get();
-		assertEquals(queryOp.get("$query"), query);
-		assertEquals(queryOp.get("$orderby"), orderBy);
-		assertEquals(queryOp.get("$hint"), hintObj);
-		
-		queryOp = new QueryOpBuilder().addQuery(query).addExplain(true).addSnapshot(true).get();
-		assertEquals(queryOp.get("$query"), query);
-		assertNull(queryOp.get("$orderby"));
-		assertNull(queryOp.get("$hint"));
-		assertEquals(queryOp.get("$explain"), true);
-		assertEquals(queryOp.get("$snapshot"), true);
-		
-		queryOp = new QueryOpBuilder().addQuery(query).addSpecialFields(new BasicDBObject("flag", "val")).get();
-		assertEquals(queryOp.get("flag"), "val");
-		assertEquals(queryOp.get("$query"), query);
-		assertNull(queryOp.get("$orderby"));
-		assertNull(queryOp.get("$hint"));
-		assertNull(queryOp.get("$explain"));
-		assertNull(queryOp.get("$snapshot"));
-		
-		queryOp = new QueryOpBuilder().addQuery(query).addReadPreference(readPref).get();
+public class QueryOpTest extends TestCase {
+
+    @Test
+    public void testQueryOnly() {
+        DBObject query = QueryBuilder.start("x").greaterThan(1).get();
+        DBObject obj = new QueryOpBuilder().addQuery(QueryBuilder.start("x").greaterThan(1).get()).get();
+        assertEquals(query, obj);
+
+        assertNotNull(new QueryOpBuilder().get());
+
+    }
+
+    @Test
+    public void testQueryAndOthers() {
+        DBObject query = QueryBuilder.start("x").greaterThan(1).get();
+        DBObject orderBy = new BasicDBObject("x", 1);
+        DBObject hintObj = new BasicDBObject("x_i", 1);
+        String hintStr = "y_i";
+
+
+        DBObject queryOp = new QueryOpBuilder().addQuery(query).addOrderBy(orderBy).addHint(hintStr).get();
+        assertEquals(queryOp.get("$query"), query);
+        assertEquals(queryOp.get("$orderby"), orderBy);
+        assertEquals(queryOp.get("$hint"), hintStr);
+        assertNull(queryOp.get("$explain"));
+        assertNull(queryOp.get("$snapshot"));
+
+        //orderby should only be there if added
+        queryOp = new QueryOpBuilder().addQuery(query).addHint(hintStr).get();
+        assertEquals(queryOp.get("$query"), query);
+        assertNull(queryOp.get("$orderby"));
+
+        //hintObj takes precedence over hintStr
+        queryOp = new QueryOpBuilder().addQuery(query).addOrderBy(orderBy).addHint(hintStr).addHint(hintObj).get();
+        assertEquals(queryOp.get("$query"), query);
+        assertEquals(queryOp.get("$orderby"), orderBy);
+        assertEquals(queryOp.get("$hint"), hintObj);
+
+        queryOp = new QueryOpBuilder().addQuery(query).addExplain(true).addSnapshot(true).get();
+        assertEquals(queryOp.get("$query"), query);
+        assertNull(queryOp.get("$orderby"));
+        assertNull(queryOp.get("$hint"));
+        assertEquals(queryOp.get("$explain"), true);
+        assertEquals(queryOp.get("$snapshot"), true);
+
+        queryOp = new QueryOpBuilder().addQuery(query).addSpecialFields(new BasicDBObject("flag", "val")).get();
+        assertEquals(queryOp.get("flag"), "val");
+        assertEquals(queryOp.get("$query"), query);
+        assertNull(queryOp.get("$orderby"));
+        assertNull(queryOp.get("$hint"));
+        assertNull(queryOp.get("$explain"));
+        assertNull(queryOp.get("$snapshot"));
+
+
+        // only append $readPreference if the read preference is not ReadPreference.primary()
+
+        queryOp = new QueryOpBuilder().addQuery(query).addReadPreference(ReadPreference.primary()).get();
+        assertEquals(queryOp.get("$query"), query);
+        assertNull(queryOp.get("$orderby"));
+        assertNull(queryOp.get("$hint"));
+        assertNull(queryOp.get("$explain"));
+        assertNull(queryOp.get("$snapshot"));
+        assertNull(queryOp.get("$readPreference"));
+
+        queryOp = new QueryOpBuilder().addQuery(query).addReadPreference(ReadPreference.secondary()).get();
         assertEquals(queryOp.get("$query"), query);
         assertNull(queryOp.get("$orderby"));
         assertNull(queryOp.get("$hint"));
         assertNull(queryOp.get("$explain"));
         assertNull(queryOp.get("$snapshot"));
-        assertEquals(queryOp.get("$readPreference"), readPref);
-	}
+        assertEquals(ReadPreference.secondary().toDBObject(), queryOp.get("$readPreference"));
+    }
 }