diff --git a/src/connector/python/linux/python2/taos/cinterface.py b/src/connector/python/linux/python2/taos/cinterface.py
index 6d792fa92fb384b41e452a7a37c55f3fd33d2a09..fe30cae6dcb3ecf817dc8dc328978ef906fe3ce9 100644
--- a/src/connector/python/linux/python2/taos/cinterface.py
+++ b/src/connector/python/linux/python2/taos/cinterface.py
@@ -146,6 +146,7 @@ class CTaosInterface(object):
     libtaos.taos_errstr.restype = ctypes.c_char_p
     libtaos.taos_subscribe.restype = ctypes.c_void_p
     libtaos.taos_consume.restype = ctypes.c_void_p
+    libtaos.taos_fetch_lengths.restype = ctypes.c_void_p
 
     def __init__(self, config=None):
         '''
@@ -314,6 +315,8 @@ class CTaosInterface(object):
 
         isMicro = (CTaosInterface.libtaos.taos_result_precision(result) == FieldType.C_TIMESTAMP_MICRO)
         blocks = [None] * len(fields)
+        fieldL = CTaosInterface.libtaos.taos_fetch_lengths(result)
+        fieldLen = [ele for ele in ctypes.cast(fieldL,  ctypes.POINTER(ctypes.c_int))[:len(fields)]]
         for i in range(len(fields)):
             data = ctypes.cast(pblock, ctypes.POINTER(ctypes.c_void_p))[i]
             if data == None:
@@ -323,7 +326,7 @@ class CTaosInterface(object):
             if fields[i]['type'] not in _CONVERT_FUNC:
                 raise DatabaseError("Invalid data type returned from database")
             
-            blocks[i] = _CONVERT_FUNC[fields[i]['type']](data, num_of_rows, fields[i]['bytes'], isMicro)
+            blocks[i] = _CONVERT_FUNC[fields[i]['type']](data, num_of_rows, fieldLen[i], isMicro)
 
         return blocks, abs(num_of_rows)
 
diff --git a/src/connector/python/windows/python2/taos/cinterface.py b/src/connector/python/windows/python2/taos/cinterface.py
index a62ac2801c2b8c61d1d0f3448e0fbf41d98aff6d..8d8a178608c30276dcc236445f629fe3656d10e1 100644
--- a/src/connector/python/windows/python2/taos/cinterface.py
+++ b/src/connector/python/windows/python2/taos/cinterface.py
@@ -146,6 +146,7 @@ class CTaosInterface(object):
     libtaos.taos_errstr.restype = ctypes.c_char_p
     libtaos.taos_subscribe.restype = ctypes.c_void_p
     libtaos.taos_consume.restype = ctypes.c_void_p
+    libtaos.taos_fetch_lengths.restype = ctypes.c_void_p
 
     def __init__(self, config=None):
         '''
@@ -314,6 +315,8 @@ class CTaosInterface(object):
 
         isMicro = (CTaosInterface.libtaos.taos_result_precision(result) == FieldType.C_TIMESTAMP_MICRO)
         blocks = [None] * len(fields)
+        fieldL = CTaosInterface.libtaos.taos_fetch_lengths(result)
+        fieldLen = [ele for ele in ctypes.cast(fieldL,  ctypes.POINTER(ctypes.c_int))[:len(fields)]]
         for i in range(len(fields)):
             data = ctypes.cast(pblock, ctypes.POINTER(ctypes.c_void_p))[i]
             if data == None:
@@ -323,7 +326,7 @@ class CTaosInterface(object):
             if fields[i]['type'] not in _CONVERT_FUNC:
                 raise DatabaseError("Invalid data type returned from database")
             
-            blocks[i] = _CONVERT_FUNC[fields[i]['type']](data, num_of_rows, fields[i]['bytes'], isMicro)
+            blocks[i] = _CONVERT_FUNC[fields[i]['type']](data, num_of_rows, fieldLen[i], isMicro)
 
         return blocks, abs(num_of_rows)
 
diff --git a/src/connector/python/windows/python3/taos/cinterface.py b/src/connector/python/windows/python3/taos/cinterface.py
index 4d009f0be0b4232d4c55c951b9ea13e1830f496a..67748160ed4337aebb84788736cd7ecaa9e09acf 100644
--- a/src/connector/python/windows/python3/taos/cinterface.py
+++ b/src/connector/python/windows/python3/taos/cinterface.py
@@ -146,6 +146,7 @@ class CTaosInterface(object):
     libtaos.taos_errstr.restype = ctypes.c_char_p
     libtaos.taos_subscribe.restype = ctypes.c_void_p
     libtaos.taos_consume.restype = ctypes.c_void_p
+    libtaos.taos_fetch_lengths.restype = ctypes.c_void_p
 
     def __init__(self, config=None):
         '''
@@ -314,6 +315,8 @@ class CTaosInterface(object):
 
         isMicro = (CTaosInterface.libtaos.taos_result_precision(result) == FieldType.C_TIMESTAMP_MICRO)
         blocks = [None] * len(fields)
+        fieldL = CTaosInterface.libtaos.taos_fetch_lengths(result)
+        fieldLen = [ele for ele in ctypes.cast(fieldL,  ctypes.POINTER(ctypes.c_int))[:len(fields)]]
         for i in range(len(fields)):
             data = ctypes.cast(pblock, ctypes.POINTER(ctypes.c_void_p))[i]
             if data == None:
@@ -323,7 +326,7 @@ class CTaosInterface(object):
             if fields[i]['type'] not in _CONVERT_FUNC:
                 raise DatabaseError("Invalid data type returned from database")
             
-            blocks[i] = _CONVERT_FUNC[fields[i]['type']](data, num_of_rows, fields[i]['bytes'], isMicro)
+            blocks[i] = _CONVERT_FUNC[fields[i]['type']](data, num_of_rows, fieldLen[i], isMicro)
 
         return blocks, abs(num_of_rows)
 
diff --git a/src/plugins/http/src/gcJson.c b/src/plugins/http/src/gcJson.c
index 09990c123e6b3c0716bc38252689fbfa1ae46394..544a11b5fc925c8c948e26f182e5d1cbd8b1e4c3 100644
--- a/src/plugins/http/src/gcJson.c
+++ b/src/plugins/http/src/gcJson.c
@@ -121,10 +121,11 @@ bool gcBuildQueryJson(HttpContext *pContext, HttpSqlCmd *cmd, TAOS_RES *result,
 
   for (int k = 0; k < numOfRows; ++k) {
     TAOS_ROW row = taos_fetch_row(result);
+    int32_t* length = taos_fetch_lengths(result);
 
     // for group by
     if (groupFields != -1) {
-      char target[HTTP_GC_TARGET_SIZE];
+      char target[HTTP_GC_TARGET_SIZE] = {0};
       int len;
       len = snprintf(target,HTTP_GC_TARGET_SIZE,"%s{",aliasBuffer);
       for (int i = dataFields + 1; i<num_fields; i++){
@@ -150,7 +151,11 @@ bool gcBuildQueryJson(HttpContext *pContext, HttpSqlCmd *cmd, TAOS_RES *result,
             break;
           case TSDB_DATA_TYPE_BINARY:
           case TSDB_DATA_TYPE_NCHAR:
-            len += snprintf(target + len, HTTP_GC_TARGET_SIZE - len, "%s:%s", fields[i].name, (char *)row[i]);
+            if (row[i]!= NULL){            
+              len += snprintf(target + len, HTTP_GC_TARGET_SIZE - len, "%s:", fields[i].name);
+              memcpy(target + len, (char *) row[i], length[i]);
+              len = strlen(target);
+            }
             break;
           default:
             len += snprintf(target + len, HTTP_GC_TARGET_SIZE - len, "%s:%s", fields[i].name, "-");