[TD-3158]<enhance>: add head_type fileds with RESTful API

src/plugins/http/inc/httpRestJson.h

@@ -34,6 +34,8 @@
 #define REST_JSON_DATA_LEN       4
 #define REST_JSON_HEAD           "head"
 #define REST_JSON_HEAD_LEN       4
+#define REST_JSON_HEAD_TYPE      "head_type"
+#define REST_JSON_HEAD_TYPE_LEN  9
 #define REST_JSON_ROWS           "rows"
 #define REST_JSON_ROWS_LEN       4
 #define REST_JSON_AFFECT_ROWS    "affected_rows"
@@ -51,4 +53,4 @@ bool restBuildSqlLocalTimeStringJson(HttpContext *pContext, HttpSqlCmd *cmd, TAO
 bool restBuildSqlUtcTimeStringJson(HttpContext *pContext, HttpSqlCmd *cmd, TAOS_RES *result, int32_t numOfRows);
 void restStopSqlJson(HttpContext *pContext, HttpSqlCmd *cmd);
 
-#endif
+#endif
\ No newline at end of file

src/plugins/http/src/httpRestJson.c

@@ -75,6 +75,26 @@ void restStartSqlJson(HttpContext *pContext, HttpSqlCmd *cmd, TAOS_RES *result)
   // head array end
   httpJsonToken(jsonBuf, JsonArrEnd);
 
+  // head_type begin
+  httpJsonItemToken(jsonBuf);
+  httpJsonPairHead(jsonBuf, REST_JSON_HEAD_TYPE, REST_JSON_HEAD_TYPE_LEN);
+  // head_type array begin
+  httpJsonItemToken(jsonBuf);
+  httpJsonToken(jsonBuf, JsonArrStt);
+
+  if (num_fields == 0) {
+    httpJsonItemToken(jsonBuf);
+    httpJsonInt(jsonBuf, TSDB_DATA_TYPE_INT);
+  } else {
+    for (int32_t i = 0; i < num_fields; ++i) {
+      httpJsonItemToken(jsonBuf);
+      httpJsonInt(jsonBuf, fields[i].type);
+    }
+  }
+
+  // head_type array end
+  httpJsonToken(jsonBuf, JsonArrEnd);
+
   // data begin
   httpJsonItemToken(jsonBuf);
   httpJsonPairHead(jsonBuf, REST_JSON_DATA, REST_JSON_DATA_LEN);