DATAKV-102 - Add possibility to iterate over available keys.

Adapter now exposes keys(Serializable keyspace) which allows to retrieve all keys contained in that specific region.

Fixed false test names (scan vs. entries (see DATAKV-99)) along the way.

Author: christophstrobl

src/main/java/org/springframework/data/keyvalue/core/KeyValueAdapter.java

@@ -74,13 +74,21 @@ public interface KeyValueAdapter extends DisposableBean {
 	Iterable<?> getAllOf(Serializable keyspace);
 
 	/**
-	 * Returns a {@link KeyValueIterator} that iterates over all entries. 
+	 * Returns a {@link KeyValueIterator} that iterates over all entries.
 	 * 
-	 * @param keyspace
+	 * @param keyspace must not be {@literal null}.
 	 * @return
 	 */
 	KeyValueIterator<? extends Serializable, ?> entries(Serializable keyspace);
 
+	/**
+	 * Returns all keys available in {@literal keyspace}.
+	 * 
+	 * @param keyspace must not be {@literal null}.
+	 * @return empty {@link Iterable} if no keys available or keyspace unknown.
+	 */
+	Iterable<? extends Serializable> keys(Serializable keyspace);
+
 	/**
 	 * Remove all objects of given type.
 	 * 

src/main/java/org/springframework/data/map/MapKeyValueAdapter.java

@@ -104,7 +104,6 @@ public boolean contains(Serializable id, Serializable keyspace) {
 		return get(id, keyspace) != null;
 	}
 
-
 	/* (non-Javadoc)
 	 * @see org.springframework.data.keyvalue.core.KeyValueAdapter#count(java.io.Serializable)
 	 */
@@ -153,6 +152,15 @@ public Collection<?> getAllOf(Serializable keyspace) {
 		return new ForwardingKeyValueIterator<Serializable, Object>(getKeySpaceMap(keyspace).entrySet().iterator());
 	}
 
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.data.keyvalue.core.KeyValueAdapter#keys(java.io.Serializable)
+	 */
+	@Override
+	public Iterable<Serializable> keys(Serializable keyspace) {
+		return getKeySpaceMap(keyspace).keySet();
+	}
+
 	/*
 	 * (non-Javadoc)
 	 * @see org.springframework.data.keyvalue.core.KeyValueAdapter#deleteAllOf(java.io.Serializable)

src/test/java/org/springframework/data/map/MapKeyValueAdapterUnitTests.java

@@ -15,6 +15,7 @@
  */
 package org.springframework.data.map;
 
+import static org.hamcrest.collection.IsEmptyIterable.*;
 import static org.hamcrest.collection.IsIterableContainingInAnyOrder.*;
 import static org.hamcrest.core.Is.*;
 import static org.hamcrest.core.IsEqual.*;
@@ -24,6 +25,8 @@
 
 import java.io.Serializable;
 
+import org.hamcrest.collection.IsIterableContainingInAnyOrder;
+import org.hamcrest.collection.IsIterableWithSize;
 import org.junit.Before;
 import org.junit.Test;
 import org.springframework.data.keyvalue.core.KeyValueIterator;
@@ -193,7 +196,7 @@ public void deleteShouldReturnDeletedObject() {
 	 * @see DATAKV-99
 	 */
 	@Test
-	public void scanShouldIterateOverAvailableEntries() {
+	public void entriesShouldIterateOverAvailableEntries() {
 
 		adapter.put("1", object1, COLLECTION_1);
 		adapter.put("2", object2, COLLECTION_1);
@@ -209,15 +212,15 @@ public void scanShouldIterateOverAvailableEntries() {
 	 * @see DATAKV-99
 	 */
 	@Test
-	public void scanShouldReturnEmptyIteratorWhenNoElementsAvailable() {
+	public void entriesShouldReturnEmptyIteratorWhenNoElementsAvailable() {
 		assertThat(adapter.entries(COLLECTION_1).hasNext(), is(false));
 	}
 
 	/**
 	 * @see DATAKV-99
 	 */
 	@Test
-	public void scanDoesNotMixResultsFromMultipleKeyspaces() {
+	public void entriesShouldNotMixResultsFromMultipleKeyspaces() {
 
 		adapter.put("1", object1, COLLECTION_1);
 		adapter.put("2", object2, COLLECTION_2);
@@ -228,6 +231,40 @@ public void scanDoesNotMixResultsFromMultipleKeyspaces() {
 		assertThat(iterator.hasNext(), is(false));
 	}
 
+	/**
+	 * @see DATAKV-102
+	 */
+	@Test
+	public void keysShouldReturnAvailableKeys() {
+
+		adapter.put("1", object1, COLLECTION_1);
+		adapter.put("2", object2, COLLECTION_1);
+
+		Iterable<Serializable> iterable = adapter.keys(COLLECTION_1);
+
+		assertThat(iterable, IsIterableContainingInAnyOrder.<Serializable> containsInAnyOrder("1", "2"));
+	}
+
+	/**
+	 * @see DATAKV-102
+	 */
+	@Test
+	public void keyShouldReturnEmptyIterableWhenNoElementsAvailable() {
+		assertThat(adapter.keys(COLLECTION_1), emptyIterable());
+	}
+
+	/**
+	 * @see DATAKV-102
+	 */
+	@Test
+	public void keysShouldNotMixResultsFromMultipleKeyspaces() {
+
+		adapter.put("1", object1, COLLECTION_1);
+		adapter.put("2", object2, COLLECTION_2);
+
+		assertThat(adapter.keys(COLLECTION_1), IsIterableWithSize.<Serializable> iterableWithSize(1));
+	}
+
 	static class SimpleObject {
 
 		protected String stringValue;