DATAREDIS-698 - Add support for HSTRLEN.

We now support HSTRLEN command throughout RedisHashCommand for Lettuce and Jedis in both an imperative and reactive manner.

However, Jedis not natively supporting HSTRLEN via its API we’ve come up with some more reflective invocation allowing to execute commands currently not known by Jedis. We also added this behavior to the cluster implementation which as of now also supports RedisClusterConnection#execute.

Author: christophstrobl

Diff for: src/main/java/org/springframework/data/redis/connection/DefaultStringRedisConnection.java

@@ -3201,6 +3201,16 @@ public Cursor<Entry<byte[], byte[]>> hScan(byte[] key, ScanOptions options) {
 		return this.delegate.hScan(key, options);
 	}
 
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.data.redis.connection.RedisSetCommands#hStrLen(byte[], byte[])
+	 */
+	@Nullable
+	@Override
+	public Long hStrLen(byte[] key, byte[] field) {
+		return convertAndReturn(delegate.hStrLen(key, field), identityConverter);
+	}
+
 	/*
 	 * (non-Javadoc)
 	 * @see org.springframework.data.redis.connection.RedisServerCommands#setClientName(java.lang.String)
@@ -3263,6 +3273,15 @@ public String setValue(String value) {
 				});
 	}
 
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.data.redis.connection.StringRedisConnection#hStrLen(java.lang.String, java.lang.String)
+	 */
+	@Override
+	public Long hStrLen(String key, String field) {
+		return hStrLen(serialize(key), serialize(field));
+	}
+
 	/*
 	 * (non-Javadoc)
 	 * @see org.springframework.data.redis.connection.StringRedisConnection#sScan(java.lang.String, org.springframework.data.redis.core.ScanOptions)
@@ -3472,8 +3491,8 @@ private <T> T convertAndReturn(@Nullable Object value, Converter converter) {
 			return null;
 		}
 
-
-		return value == null ? null : ObjectUtils.nullSafeEquals(converter, identityConverter) ? (T) value : (T) converter.convert(value);
+		return value == null ? null
+				: ObjectUtils.nullSafeEquals(converter, identityConverter) ? (T) value : (T) converter.convert(value);
 	}
 
 	private void addResultConverter(Converter<?, ?> converter) {

Diff for: src/main/java/org/springframework/data/redis/connection/DefaultedRedisClusterConnection.java

@@ -15,10 +15,14 @@
  */
 package org.springframework.data.redis.connection;
 
+import java.util.ArrayList;
+import java.util.Collection;
 import java.util.List;
 import java.util.Properties;
 
 import org.springframework.data.redis.core.types.RedisClientInfo;
+import org.springframework.lang.Nullable;
+import org.springframework.util.Assert;
 
 /**
  * @author Christoph Strobl
@@ -131,4 +135,23 @@ default Long time(RedisClusterNode node) {
 	default List<RedisClientInfo> getClientList(RedisClusterNode node) {
 		return serverCommands().getClientList(node);
 	}
+
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.data.redis.connection.RedisClusterConnection#execute(String, byte[], Collection)
+	 */
+	@Nullable
+	@Override
+	default <T> T execute(String command, byte[] key, Collection<byte[]> args) {
+
+		Assert.notNull(command, "Command must not be null!");
+		Assert.notNull(key, "Key must not be null!");
+		Assert.notNull(args, "Args must not be null!");
+
+		ArrayList<byte[]> allArgs = new ArrayList();
+		allArgs.add(key);
+		allArgs.addAll(args);
+
+		return (T) execute(command, allArgs.toArray(new byte[allArgs.size()][]));
+	}
 }

Diff for: src/main/java/org/springframework/data/redis/connection/DefaultedRedisConnection.java

@@ -916,6 +916,13 @@ default Cursor<Entry<byte[], byte[]>> hScan(byte[] key, ScanOptions options) {
 		return hashCommands().hScan(key, options);
 	}
 
+	/** @deprecated in favor of {@link RedisConnection#hashCommands()}. */
+	@Override
+	@Deprecated
+	default Long hStrLen(byte[] key, byte[] field) {
+		return hashCommands().hStrLen(key, field);
+	}
+
 	// GEO COMMANDS
 
 	/** @deprecated in favor of {@link RedisConnection#geoCommands()}}. */

Diff for: src/main/java/org/springframework/data/redis/connection/ReactiveHashCommands.java

@@ -578,4 +578,83 @@ default Flux<Map.Entry<ByteBuffer, ByteBuffer>> hGetAll(ByteBuffer key) {
 	 * @see <a href="http://redis.io/commands/hgetall">Redis Documentation: HGETALL</a>
 	 */
 	Flux<CommandResponse<KeyCommand, Flux<Map.Entry<ByteBuffer, ByteBuffer>>>> hGetAll(Publisher<KeyCommand> commands);
+
+	/**
+	 * @author Christoph Strobl
+	 * @see <a href="http://redis.io/commands/hstrlen">Redis Documentation: HSTRLEN</a>
+	 * @since 2.1
+	 */
+	class HStrLenCommand extends KeyCommand {
+
+		private ByteBuffer field;
+
+		/**
+		 * Creates a new {@link HStrLenCommand} given a {@code key}.
+		 *
+		 * @param key can be {@literal null}.
+		 * @param field must not be {@literal null}.
+		 */
+		private HStrLenCommand(@Nullable ByteBuffer key, ByteBuffer field) {
+
+			super(key);
+			this.field = field;
+		}
+
+		/**
+		 * Specify the {@code field} within the hash to get the length of the {@code value} of.ø
+		 *
+		 * @param field must not be {@literal null}.
+		 * @return new instance of {@link HStrLenCommand}.
+		 */
+		public static HStrLenCommand lengthOf(ByteBuffer field) {
+
+			Assert.notNull(field, "Field must not be null!");
+			return new HStrLenCommand(null, field);
+		}
+
+		/**
+		 * Define the {@code key} the hash is stored at.
+		 *
+		 * @param key must not be {@literal null}.
+		 * @return new instance of {@link HStrLenCommand}.
+		 */
+		public HStrLenCommand from(ByteBuffer key) {
+			return new HStrLenCommand(key, field);
+		}
+
+		/**
+		 * @return {@literal null} if not already set.
+		 */
+		@Nullable
+		public ByteBuffer getField() {
+			return field;
+		}
+	}
+
+	/**
+	 * Get the length of the value associated with {@code hashKey}. If either the {@code key} or the {@code hashKey} do
+	 * not exist, {@code 0} is emitted.
+	 *
+	 * @param key must not be {@literal null}.
+	 * @param field must not be {@literal null}.
+	 * @return never {@literal null}.
+	 * @since 2.1
+	 */
+	default Mono<Long> hStrLen(ByteBuffer key, ByteBuffer field) {
+
+		Assert.notNull(key, "Key must not be null!");
+		Assert.notNull(field, "Field must not be null!");
+
+		return hStrLen(Mono.just(HStrLenCommand.lengthOf(field).from(key))).next().map(NumericResponse::getOutput);
+	}
+
+	/**
+	 * Get the length of the value associated with {@code hashKey}. If either the {@code key} or the {@code hashKey} do
+	 * not exist, {@code 0} is emitted.
+	 *
+	 * @param commands must not be {@literal null}.
+	 * @return never {@literal null}.
+	 * @since 2.1
+	 */
+	Flux<NumericResponse<HStrLenCommand, Long>> hStrLen(Publisher<HStrLenCommand> commands);
 }

Diff for: src/main/java/org/springframework/data/redis/connection/RedisClusterConnection.java

@@ -15,6 +15,7 @@
  */
 package org.springframework.data.redis.connection;
 
+import java.util.Collection;
 import java.util.Set;
 
 import org.springframework.lang.Nullable;
@@ -56,6 +57,27 @@ public interface RedisClusterConnection extends RedisConnection, RedisClusterCom
 	@Nullable
 	byte[] randomKey(RedisClusterNode node);
 
+	/**
+	 * Execute the given command for the {@code key} provided potentially appending args. <br />
+	 * This method, other than {@link #execute(String, byte[]...)}, dispatches the command to the {@code key} serving
+	 * master node.
+	 *
+	 * <pre>
+	 * <code>
+	 * // SET foo bar EX 10 NX
+	 * execute("SET", "foo".getBytes(), asBinaryList("bar", "EX", 10, "NX")
+	 * </code>
+	 * </pre>
+	 *
+	 * @param command must not be {@literal null}.
+	 * @param key must not be {@literal null}.
+	 * @param args must not be {@literal null}.
+	 * @return command result as delivered by the underlying Redis driver. Can be {@literal null}.
+	 * @since 2.1
+	 */
+	@Nullable
+	<T> T execute(String command, byte[] key, Collection<byte[]> args);
+
 	/**
 	 * Get {@link RedisClusterServerCommands}.
 	 *

Diff for: src/main/java/org/springframework/data/redis/connection/RedisHashCommands.java

@@ -183,4 +183,16 @@ public interface RedisHashCommands {
 	 * @see <a href="http://redis.io/commands/hscan">Redis Documentation: HSCAN</a>
 	 */
 	Cursor<Map.Entry<byte[], byte[]>> hScan(byte[] key, ScanOptions options);
+
+	/**
+	 * Returns the length of the value associated with {@code field} in the hash stored at {@code key}. If the key or the
+	 * field do not exist, {@code 0} is returned.
+	 *
+	 * @param key must not be {@literal null}.
+	 * @param field must not be {@literal null}.
+	 * @return {@literal null} when used in pipeline / transaction.
+	 * @since 2.1
+	 */
+	@Nullable
+	Long hStrLen(byte[] key, byte[] field);
 }

Diff for: src/main/java/org/springframework/data/redis/connection/StringRedisConnection.java

@@ -1509,6 +1509,18 @@ interface StringTuple extends Tuple {
 	 */
 	Cursor<Map.Entry<String, String>> hScan(String key, ScanOptions options);
 
+	/**
+	 * Returns the length of the value associated with {@code field} in the hash stored at {@code key}. If the key or the
+	 * field do not exist, {@code 0} is returned.
+	 *
+	 * @param key must not be {@literal null}.
+	 * @param field must not be {@literal null}.
+	 * @return {@literal null} when used in pipeline / transaction.
+	 * @since 2.1
+	 */
+	@Nullable
+	Long hStrLen(String key, String field);
+
 	// -------------------------------------------------------------------------
 	// Methods dealing with HyperLogLog
 	// -------------------------------------------------------------------------