Add support for ZRANDMEMBER.

Closes: #2049
Original Pull Request: #2104

Author: mp911de

src/main/asciidoc/new-features.adoc

@@ -7,7 +7,7 @@ This section briefly covers items that are new and noteworthy in the latest rele
 == New in Spring Data Redis 2.6
 
 * Support for `SubscriptionListener` when using `MessageListener` for subscription confirmation callbacks. `ReactiveRedisMessageListenerContainer` and `ReactiveRedisOperations` provide `receiveLater(…)` and `listenToLater(…)` methods to await until Redis acknowledges the subscription.
-* Support Redis 6.2 commands (`LPOP`/`RPOP` with `count`, `COPY`, `GETEX`, `GETDEL`, `ZPOPMIN`, `BZPOPMIN`, `ZPOPMAX`, `BZPOPMAX`, `ZMSCORE`, `ZDIFF`, `ZDIFFSTORE`, `ZINTER`, `ZUNION`, `HRANDFIELD`).
+* Support Redis 6.2 commands (`LPOP`/`RPOP` with `count`, `COPY`, `GETEX`, `GETDEL`, `ZPOPMIN`, `BZPOPMIN`, `ZPOPMAX`, `BZPOPMAX`, `ZMSCORE`, `ZDIFF`, `ZDIFFSTORE`, `ZINTER`, `ZUNION`, `HRANDFIELD`, `ZRANDMEMBER`).
 
 [[new-in-2.5.0]]
 == New in Spring Data Redis 2.5

src/main/java/org/springframework/data/redis/connection/DefaultStringRedisConnection.java

@@ -85,6 +85,7 @@ public class DefaultStringRedisConnection implements StringRedisConnection, Deco
 	private final TupleConverter tupleConverter = new TupleConverter();
 	private SetConverter<Tuple, StringTuple> tupleToStringTuple = new SetConverter<>(tupleConverter);
 	private SetConverter<StringTuple, Tuple> stringTupleToTuple = new SetConverter<>(new StringTupleConverter());
+	private ListConverter<Tuple, StringTuple> tupleListToStringTuple = new ListConverter<>(new TupleConverter());
 	private ListConverter<byte[], String> byteListToStringList = new ListConverter<>(bytesToString);
 	private MapConverter<byte[], String> byteMapToStringMap = new MapConverter<>(bytesToString);
 	private MapConverter<String, byte[]> stringMapToByteMap = new MapConverter<>(stringToBytes);
@@ -3296,6 +3297,78 @@ public Long zInterStore(String destKey, String... sets) {
 		return zInterStore(serialize(destKey), serializeMulti(sets));
 	}
 
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.data.redis.connection.RedisZSetCommands#zRandMember(byte[])
+	 */
+	@Override
+	public byte[] zRandMember(byte[] key) {
+		return delegate.zRandMember(key);
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.data.redis.connection.RedisZSetCommands#zRandMember(byte[], long)
+	 */
+	@Override
+	public List<byte[]> zRandMember(byte[] key, long count) {
+		return delegate.zRandMember(key, count);
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.data.redis.connection.RedisZSetCommands#zRandMemberWithScore(byte[])
+	 */
+	@Override
+	public Tuple zRandMemberWithScore(byte[] key) {
+		return delegate.zRandMemberWithScore(key);
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.data.redis.connection.RedisZSetCommands#zRandMemberWithScore(byte[], long)
+	 */
+	@Override
+	public List<Tuple> zRandMemberWithScore(byte[] key, long count) {
+		return delegate.zRandMemberWithScore(key, count);
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.data.redis.connection.StringRedisConnection#zRandMember(java.lang.String)
+	 */
+	@Override
+	public String zRandMember(String key) {
+		return convertAndReturn(delegate.zRandMember(serialize(key)), bytesToString);
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.data.redis.connection.StringRedisConnection#zRandMember(java.lang.String, long)
+	 */
+	@Override
+	public List<String> zRandMember(String key, long count) {
+		return convertAndReturn(delegate.zRandMember(serialize(key), count), byteListToStringList);
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.data.redis.connection.StringRedisConnection#zRandMemberWithScore(java.lang.String)
+	 */
+	@Override
+	public StringTuple zRandMemberWithScore(String key) {
+		return convertAndReturn(delegate.zRandMemberWithScore(serialize(key)), new TupleConverter());
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.data.redis.connection.StringRedisConnection#zRandMemberWithScores(java.lang.String, long)
+	 */
+	@Override
+	public List<StringTuple> zRandMemberWithScores(String key, long count) {
+		return convertAndReturn(delegate.zRandMemberWithScore(serialize(key), count), tupleListToStringTuple);
+	}
+
 	/*
 	 * (non-Javadoc)
 	 * @see org.springframework.data.redis.connection.StringRedisConnection#zRange(java.lang.String, long, long)

src/main/java/org/springframework/data/redis/connection/DefaultedRedisConnection.java

@@ -1068,6 +1068,34 @@ default Long zInterStore(byte[] destKey, byte[]... sets) {
 		return zSetCommands().zInterStore(destKey, sets);
 	}
 
+	/** @deprecated in favor of {@link RedisConnection#zSetCommands()}}. */
+	@Override
+	@Deprecated
+	default byte[] zRandMember(byte[] key) {
+		return zSetCommands().zRandMember(key);
+	}
+
+	/** @deprecated in favor of {@link RedisConnection#zSetCommands()}}. */
+	@Override
+	@Deprecated
+	default List<byte[]> zRandMember(byte[] key, long count) {
+		return zSetCommands().zRandMember(key, count);
+	}
+
+	/** @deprecated in favor of {@link RedisConnection#zSetCommands()}}. */
+	@Override
+	@Deprecated
+	default Tuple zRandMemberWithScore(byte[] key) {
+		return zSetCommands().zRandMemberWithScore(key);
+	}
+
+	/** @deprecated in favor of {@link RedisConnection#zSetCommands()}}. */
+	@Override
+	@Deprecated
+	default List<Tuple> zRandMemberWithScore(byte[] key, long count) {
+		return zSetCommands().zRandMemberWithScore(key, count);
+	}
+
 	/** @deprecated in favor of {@link RedisConnection#zSetCommands()}}. */
 	@Override
 	@Deprecated

src/main/java/org/springframework/data/redis/connection/ReactiveZSetCommands.java

@@ -477,6 +477,142 @@ default Mono<Double> zIncrBy(ByteBuffer key, Number increment, ByteBuffer value)
 	 */
 	Flux<NumericResponse<ZIncrByCommand, Double>> zIncrBy(Publisher<ZIncrByCommand> commands);
 
+	/**
+	 * {@code ZRANDMEMBER} command parameters.
+	 *
+	 * @author Mark Paluch
+	 * @since 2.6
+	 * @see <a href="https://redis.io/commands/srandmember">Redis Documentation: ZRANDMEMBER</a>
+	 */
+	class ZRandMemberCommand extends KeyCommand {
+
+		private final long count;
+
+		private ZRandMemberCommand(@Nullable ByteBuffer key, long count) {
+
+			super(key);
+			this.count = count;
+		}
+
+		/**
+		 * Creates a new {@link ZRandMemberCommand} given the number of values to retrieve.
+		 *
+		 * @param nrValuesToRetrieve
+		 * @return a new {@link ZRandMemberCommand} for a number of values to retrieve.
+		 */
+		public static ZRandMemberCommand valueCount(long nrValuesToRetrieve) {
+			return new ZRandMemberCommand(null, nrValuesToRetrieve);
+		}
+
+		/**
+		 * Creates a new {@link ZRandMemberCommand} to retrieve one random member.
+		 *
+		 * @return a new {@link ZRandMemberCommand} to retrieve one random member.
+		 */
+		public static ZRandMemberCommand singleValue() {
+			return new ZRandMemberCommand(null, 1);
+		}
+
+		/**
+		 * Applies the {@literal key}. Constructs a new command instance with all previously configured properties.
+		 *
+		 * @param key must not be {@literal null}.
+		 * @return a new {@link ZRandMemberCommand} with {@literal key} applied.
+		 */
+		public ZRandMemberCommand from(ByteBuffer key) {
+
+			Assert.notNull(key, "Key must not be null!");
+
+			return new ZRandMemberCommand(key, count);
+		}
+
+		/**
+		 * @return
+		 */
+		public long getCount() {
+			return count;
+		}
+	}
+
+	/**
+	 * Get random element from sorted set at {@code key}.
+	 *
+	 * @param key must not be {@literal null}.
+	 * @return
+	 * @since 2.6
+	 * @see <a href="https://redis.io/commands/zrandmember">Redis Documentation: ZRANDMEMBER</a>
+	 */
+	default Mono<ByteBuffer> zRandMember(ByteBuffer key) {
+		return zRandMember(Mono.just(ZRandMemberCommand.singleValue().from(key))).flatMap(CommandResponse::getOutput)
+				.next();
+	}
+
+	/**
+	 * Get {@code count} random elements from sorted set at {@code key}.
+	 *
+	 * @param key must not be {@literal null}.
+	 * @param count if the provided {@code count} argument is positive, return a list of distinct fields, capped either at
+	 *          {@code count} or the set size. If {@code count} is negative, the behavior changes and the command is
+	 *          allowed to return the same value multiple times. In this case, the number of returned values is the
+	 *          absolute value of the specified count.
+	 * @return
+	 * @since 2.6
+	 * @see <a href="https://redis.io/commands/zrandmember">Redis Documentation: ZRANDMEMBER</a>
+	 */
+	default Flux<ByteBuffer> zRandMember(ByteBuffer key, long count) {
+		return zRandMember(Mono.just(ZRandMemberCommand.valueCount(count).from(key))).flatMap(CommandResponse::getOutput);
+	}
+
+	/**
+	 * Get random elements from sorted set at {@code key}.
+	 *
+	 * @param commands must not be {@literal null}.
+	 * @return
+	 * @since 2.6
+	 * @see <a href="https://redis.io/commands/zrandmember">Redis Documentation: ZRANDMEMBER</a>
+	 */
+	Flux<CommandResponse<ZRandMemberCommand, Flux<ByteBuffer>>> zRandMember(Publisher<ZRandMemberCommand> commands);
+
+	/**
+	 * Get random element from sorted set at {@code key}.
+	 *
+	 * @param key must not be {@literal null}.
+	 * @return
+	 * @since 2.6
+	 * @see <a href="https://redis.io/commands/zrandmember">Redis Documentation: ZRANDMEMBER</a>
+	 */
+	default Mono<Tuple> zRandMemberWithScore(ByteBuffer key) {
+		return zRandMemberWithScore(Mono.just(ZRandMemberCommand.singleValue().from(key)))
+				.flatMap(CommandResponse::getOutput).next();
+	}
+
+	/**
+	 * Get {@code count} random elements from sorted set at {@code key}.
+	 *
+	 * @param key must not be {@literal null}.
+	 * @param count if the provided {@code count} argument is positive, return a list of distinct fields, capped either at
+	 *          {@code count} or the set size. If {@code count} is negative, the behavior changes and the command is
+	 *          allowed to return the same value multiple times. In this case, the number of returned values is the
+	 *          absolute value of the specified count.
+	 * @return
+	 * @since 2.6
+	 * @see <a href="https://redis.io/commands/zrandmember">Redis Documentation: ZRANDMEMBER</a>
+	 */
+	default Flux<Tuple> zRandMemberWithScore(ByteBuffer key, long count) {
+		return zRandMemberWithScore(Mono.just(ZRandMemberCommand.valueCount(count).from(key)))
+				.flatMap(CommandResponse::getOutput);
+	}
+
+	/**
+	 * Get random elements from sorted set at {@code key}.
+	 *
+	 * @param commands must not be {@literal null}.
+	 * @return
+	 * @since 2.6
+	 * @see <a href="https://redis.io/commands/zrandmember">Redis Documentation: ZRANDMEMBER</a>
+	 */
+	Flux<CommandResponse<ZRandMemberCommand, Flux<Tuple>>> zRandMemberWithScore(Publisher<ZRandMemberCommand> commands);
+
 	/**
 	 * {@code ZRANK}/{@literal ZREVRANK} command parameters.
 	 *

src/main/java/org/springframework/data/redis/connection/RedisZSetCommands.java

@@ -634,6 +634,58 @@ default Long zAdd(byte[] key, Set<Tuple> tuples) {
 	@Nullable
 	Double zIncrBy(byte[] key, double increment, byte[] value);
 
+	/**
+	 * Get random element from sorted set at {@code key}.
+	 *
+	 * @param key must not be {@literal null}.
+	 * @return can be {@literal null}.
+	 * @since 2.6
+	 * @see <a href="https://redis.io/commands/zrandmember">Redis Documentation: ZRANDMEMBER</a>
+	 */
+	@Nullable
+	byte[] zRandMember(byte[] key);
+
+	/**
+	 * Get {@code count} random elements from sorted set at {@code key}.
+	 *
+	 * @param key must not be {@literal null}.
+	 * @param count if the provided {@code count} argument is positive, return a list of distinct fields, capped either at
+	 *          {@code count} or the set size. If {@code count} is negative, the behavior changes and the command is
+	 *          allowed to return the same value multiple times. In this case, the number of returned values is the
+	 *          absolute value of the specified count.
+	 * @return {@literal null} when used in pipeline / transaction.
+	 * @since 2.6
+	 * @see <a href="https://redis.io/commands/zrandmember">Redis Documentation: ZRANDMEMBER</a>
+	 */
+	@Nullable
+	List<byte[]> zRandMember(byte[] key, long count);
+
+	/**
+	 * Get random element from sorted set at {@code key}.
+	 *
+	 * @param key must not be {@literal null}.
+	 * @return can be {@literal null}.
+	 * @since 2.6
+	 * @see <a href="https://redis.io/commands/zrandmember">Redis Documentation: ZRANDMEMBER</a>
+	 */
+	@Nullable
+	Tuple zRandMemberWithScore(byte[] key);
+
+	/**
+	 * Get {@code count} random elements from sorted set at {@code key}.
+	 *
+	 * @param key must not be {@literal null}.
+	 * @param count if the provided {@code count} argument is positive, return a list of distinct fields, capped either at
+	 *          {@code count} or the set size. If {@code count} is negative, the behavior changes and the command is
+	 *          allowed to return the same value multiple times. In this case, the number of returned values is the
+	 *          absolute value of the specified count.
+	 * @return {@literal null} when used in pipeline / transaction.
+	 * @since 2.6
+	 * @see <a href="https://redis.io/commands/zrandmember">Redis Documentation: ZRANDMEMBER</a>
+	 */
+	@Nullable
+	List<Tuple> zRandMemberWithScore(byte[] key, long count);
+
 	/**
 	 * Determine the index of element with {@code value} in a sorted set.
 	 *

src/main/java/org/springframework/data/redis/connection/StringRedisConnection.java

@@ -1229,6 +1229,58 @@ default Long lPos(String key, String element) {
 	 */
 	Double zIncrBy(String key, double increment, String value);
 
+	/**
+	 * Get random element from sorted set at {@code key}.
+	 *
+	 * @param key must not be {@literal null}.
+	 * @return can be {@literal null}.
+	 * @since 2.6
+	 * @see <a href="https://redis.io/commands/zrandmember">Redis Documentation: ZRANDMEMBER</a>
+	 */
+	@Nullable
+	String zRandMember(String key);
+
+	/**
+	 * Get {@code count} random elements from sorted set at {@code key}.
+	 *
+	 * @param key must not be {@literal null}.
+	 * @param count if the provided {@code count} argument is positive, return a list of distinct fields, capped either at
+	 *          {@code count} or the set size. If {@code count} is negative, the behavior changes and the command is
+	 *          allowed to return the same value multiple times. In this case, the number of returned values is the
+	 *          absolute value of the specified count.
+	 * @return {@literal null} when used in pipeline / transaction.
+	 * @since 2.6
+	 * @see <a href="https://redis.io/commands/zrandmember">Redis Documentation: ZRANDMEMBER</a>
+	 */
+	@Nullable
+	List<String> zRandMember(String key, long count);
+
+	/**
+	 * Get random element from sorted set at {@code key}.
+	 *
+	 * @param key must not be {@literal null}.
+	 * @return can be {@literal null}.
+	 * @since 2.6
+	 * @see <a href="https://redis.io/commands/zrandmember">Redis Documentation: ZRANDMEMBER</a>
+	 */
+	@Nullable
+	StringTuple zRandMemberWithScore(String key);
+
+	/**
+	 * Get {@code count} random elements from sorted set at {@code key}.
+	 *
+	 * @param key must not be {@literal null}.
+	 * @param count if the provided {@code count} argument is positive, return a list of distinct fields, capped either at
+	 *          {@code count} or the set size. If {@code count} is negative, the behavior changes and the command is
+	 *          allowed to return the same value multiple times. In this case, the number of returned values is the
+	 *          absolute value of the specified count.
+	 * @return {@literal null} when used in pipeline / transaction.
+	 * @since 2.6
+	 * @see <a href="https://redis.io/commands/zrandmember">Redis Documentation: ZRANDMEMBER</a>
+	 */
+	@Nullable
+	List<StringTuple> zRandMemberWithScores(String key, long count);
+
 	/**
 	 * Determine the index of element with {@code value} in a sorted set.
 	 *