DATAMONGO-941 - Add support for $min to Update.

Added new methods to Update.
Added bunch of unit tests (some failing) - have to get them running.

Author: christophstrobl

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/query/Update.java

@@ -20,6 +20,7 @@
 import java.util.Arrays;
 import java.util.Collection;
 import java.util.Collections;
+import java.util.Date;
 import java.util.HashSet;
 import java.util.LinkedHashMap;
 import java.util.List;
@@ -336,6 +337,38 @@ public BitwiseOperatorBuilder bitwise(String key) {
 		return new BitwiseOperatorBuilder(this, key);
 	}
 
+	/**
+	 * Update given key to value if the given value is less than the current value of the field.
+	 * 
+	 * @see http://docs.mongodb.org/manual/reference/operator/update/min/
+	 * @param key must not be {@literal null}.
+	 * @param value must not be {@literal null}.
+	 * @return
+	 * @since 1.7
+	 */
+	public Update min(String key, Number value) {
+
+		Assert.notNull(value, "Value for min operation must not be 'null'.");
+		addMultiFieldOperation("$min", key, value);
+		return this;
+	}
+
+	/**
+	 * Update given key to value if the given date is before than the current date value of the field.
+	 * 
+	 * @see http://docs.mongodb.org/manual/reference/operator/update/min/
+	 * @param key must not be {@literal null}.
+	 * @param value must not be {@literal null}.
+	 * @return
+	 * @since 1.7
+	 */
+	public Update min(String key, Date value) {
+
+		Assert.notNull(value, "Value for min operation must not be 'null'.");
+		addMultiFieldOperation("$min", key, value);
+		return this;
+	}
+
 	public DBObject getUpdateObject() {
 
 		DBObject dbo = new BasicDBObject();

spring-data-mongodb/src/test/java/org/springframework/data/mongodb/core/DBObjectTestUtils.java

@@ -18,20 +18,70 @@
 import static org.hamcrest.Matchers.*;
 import static org.junit.Assert.*;
 
+import java.util.Arrays;
+import java.util.Iterator;
+import java.util.NoSuchElementException;
+
 import com.mongodb.BasicDBList;
 import com.mongodb.DBObject;
 
 /**
  * Helper classes to ease assertions on {@link DBObject}s.
  * 
  * @author Oliver Gierke
+ * @autor Christoph Strobl
  */
 public abstract class DBObjectTestUtils {
 
 	private DBObjectTestUtils() {
 
 	}
 
+	/**
+	 * Extracts value for a given path within the dbo. Indexes in arrays can be addressed via {@code []}.
+	 * 
+	 * @param source
+	 * @param path
+	 * @return
+	 */
+	@SuppressWarnings("unchecked")
+	public static <T> T getValue(DBObject source, String path) {
+
+		String[] fragments = path.split("\\.");
+		if (fragments.length == 1) {
+			return (T) source.get(path);
+		}
+
+		Iterator<String> it = Arrays.asList(fragments).iterator();
+
+		DBObject dbo = source;
+		while (it.hasNext()) {
+
+			String key = it.next();
+
+			if (key.startsWith("[")) {
+				String indexNumber = key.substring(1, key.indexOf("]"));
+				dbo = getAsDBObject((BasicDBList) dbo, Integer.parseInt(indexNumber));
+			} else {
+
+				if (!it.hasNext()) {
+					return (T) dbo.get(key);
+				}
+
+				Object value = dbo.get(key);
+				if (value instanceof DBObject) {
+					dbo = (DBObject) value;
+				} else {
+					if (it.next().startsWith("$")) {
+						return (T) value;
+					}
+				}
+			}
+		}
+
+		throw new NoSuchElementException(String.format("Unable to find '%s' in %s.", path, source));
+	}
+
 	/**
 	 * Expects the field with the given key to be not {@literal null} and a {@link DBObject} in turn and returns it.
 	 * 

spring-data-mongodb/src/test/java/org/springframework/data/mongodb/core/MongoTemplateTests.java

@@ -23,14 +23,17 @@
 import static org.springframework.data.mongodb.core.query.Query.*;
 import static org.springframework.data.mongodb.core.query.Update.*;
 
+import java.math.BigDecimal;
 import java.math.BigInteger;
 import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.Calendar;
 import java.util.Collections;
 import java.util.Date;
 import java.util.HashMap;
 import java.util.HashSet;
 import java.util.List;
+import java.util.Locale;
 import java.util.Map;
 
 import org.bson.types.ObjectId;
@@ -2751,6 +2754,65 @@ public void insertsAndRemovesBasicDbObjectCorrectly() {
 		assertThat(template.findAll(DBObject.class, "collection"), hasSize(0));
 	}
 
+	/**
+	 * @see DATAMONGO-941
+	 */
+	@Test
+	public void updatesDateValueCorrectlyWhenUsingMinOperator() {
+
+		Calendar cal = Calendar.getInstance(Locale.US);
+		cal.set(2013, 10, 13, 0, 0, 0);
+
+		TypeWithDate twd = new TypeWithDate();
+		twd.date = new Date();
+		template.save(twd);
+		template.updateFirst(query(where("id").is(twd.id)), new Update().min("date", cal.getTime()), TypeWithDate.class);
+
+		TypeWithDate loaded = template.find(query(where("id").is(twd.id)), TypeWithDate.class).get(0);
+		assertThat(loaded.date, equalTo(cal.getTime()));
+	}
+
+	/**
+	 * @see DATAMONGO-941
+	 */
+	@Test
+	public void updatesNumericValueCorrectlyWhenUsingMinOperator() {
+
+		TypeWithNumbers twn = new TypeWithNumbers();
+		twn.byteVal = 100;
+		twn.doubleVal = 200D;
+		twn.floatVal = 300F;
+		twn.intVal = 400;
+		twn.longVal = 500L;
+
+		// Note that $min operator is not supported for BigInteger and BigDecimal types.
+		// twn.bigIntegerVal = new BigInteger("600");
+		// twn.bigDeciamVal = new BigDecimal("700.0");
+
+		template.save(twn);
+
+		byte byteVal = 90;
+		Update update = new Update()//
+				.min("byteVal", byteVal) //
+				.min("doubleVal", 190D) //
+				.min("floatVal", 290F) //
+				.min("intVal", 390) //
+				.min("longVal", 490) //
+		// Not supported
+		// .min("bigIntegerVal", new BigInteger("590")) //
+		// .min("bigDeciamVal", new BigDecimal("690")) //
+		;
+
+		template.updateFirst(query(where("id").is(twn.id)), update, TypeWithNumbers.class);
+
+		TypeWithNumbers loaded = template.find(query(where("id").is(twn.id)), TypeWithNumbers.class).get(0);
+		assertThat(loaded.byteVal, equalTo(byteVal));
+		assertThat(loaded.doubleVal, equalTo(190D));
+		assertThat(loaded.floatVal, equalTo(290F));
+		assertThat(loaded.intVal, equalTo(390));
+		assertThat(loaded.longVal, equalTo(490L));
+	}
+
 	static class DoucmentWithNamedIdField {
 
 		@Id String someIdKey;
@@ -3018,4 +3080,16 @@ static class SomeMessage {
 		@org.springframework.data.mongodb.core.mapping.DBRef SomeContent dbrefContent;
 		SomeContent normalContent;
 	}
+
+	static class TypeWithNumbers {
+
+		@Id String id;
+		Integer intVal;
+		Float floatVal;
+		Long longVal;
+		Double doubleVal;
+		BigDecimal bigDeciamVal;
+		BigInteger bigIntegerVal;
+		Byte byteVal;
+	}
 }