Support JSON.CLEAR command (#52)

* Support JSON.CLEAR command

* Object clear test

Author: sazzad16

src/main/java/com/redislabs/modules/rejson/JReJSON.java

@@ -63,7 +63,8 @@ private enum Command implements ProtocolCommand {
         ARRINSERT("JSON.ARRINSERT"),
         ARRLEN("JSON.ARRLEN"),
         ARRPOP("JSON.ARRPOP"),
-        ARRTRIM("JSON.ARRTRIM");
+        ARRTRIM("JSON.ARRTRIM"),
+        CLEAR("JSON.CLEAR");
 
         private final byte[] raw;
 
@@ -162,7 +163,6 @@ public Long del(String key) {
     	return del(key, Path.ROOT_PATH);
     }
 
-
     /**
      * Deletes a path
      * @param key the key name
@@ -180,6 +180,13 @@ public Long del(String key, Path path) {
     	}
     }
 
+    public long clear(String key, Path path) {
+    	  try (Jedis jedis = getConnection()) {
+    		    jedis.getClient().sendCommand(Command.CLEAR, key, path.toString());
+    		    return jedis.getClient().getIntegerReply();
+    	  }
+    }
+
     /**
      * Gets an object at the root path
      * @param key the key name

src/test/java/com/redislabs/modules/rejson/ClientTest.java

@@ -368,6 +368,35 @@ public void testArrayLength() {
       assertEquals(Long.valueOf(3L), client.arrLen( "foobar", Path.of(".fooArr")));
     }
 
+    @Test
+    public void clearArray() {
+        client.set("foobar", new FooBarObject(), Path.ROOT_PATH);
+
+        Path arrPath = Path.of(".fooArr");
+        assertEquals(Long.valueOf(3L), client.arrLen("foobar", arrPath));
+
+        assertEquals(1L, client.clear("foobar", arrPath));
+        assertEquals(Long.valueOf(0L), client.arrLen("foobar", arrPath));
+
+        // ignore non-array
+        Path strPath = Path.of("foo");
+        assertEquals(0L, client.clear("foobar", strPath));
+        assertEquals("bar", client.get("foobar", String.class, strPath));
+    }
+
+    @Test
+    public void clearObject() {
+        Baz baz = new Baz("quuz", "grault", "waldo");
+        Qux qux = new Qux("quux", "corge", "garply", baz);
+
+        client.set("qux", qux);
+        Path objPath = Path.of("baz");
+        assertEquals(baz, client.get("qux", Baz.class, objPath));
+
+        assertEquals(1L, client.clear("qux", objPath));
+        assertEquals(new Baz(null, null, null), client.get("qux", Baz.class, objPath));
+    }
+
     @Test
     public void testArrayAppendSameType() {
       String json = "{ a: 'hello', b: [1, 2, 3], c: { d: ['ello'] }}";