add empty json with null payload

Azure · Oct 1, 2021 · 9e03329 · 9e03329
1 parent d1a663b
commit 9e03329
Showing 1 changed file with 8 additions and 0 deletions.
diff --git a/iothub_client/src/iothub_client_core.c b/iothub_client/src/iothub_client_core.c
@@ -26,6 +26,7 @@
 
 #define DO_WORK_FREQ_DEFAULT 1
 #define DO_WORK_MAXIMUM_ALLOWED_FREQUENCY 100
+#define CLIENT_CORE_METHOD_EMPTY_PAYLOAD "{}"
 
 struct IOTHUB_QUEUE_CONTEXT_TAG;
 
@@ -385,6 +386,13 @@ static int iothub_ll_device_method_callback(const char* method_name, const unsig
         USER_CALLBACK_INFO queue_cb_info;
         queue_cb_info.type = CALLBACK_TYPE_DEVICE_METHOD;
 
+        // A NULL payload was sent from the service. Use empty JSON to signal to the user no payload.
+        if(size == 0)
+        {
+          payload = (const unsigned char*) CLIENT_CORE_METHOD_EMPTY_PAYLOAD;
+          size = strlen(CLIENT_CORE_METHOD_EMPTY_PAYLOAD);
+        }
+
         result = make_method_calback_queue_context(&queue_cb_info, method_name, payload, size, method_id, queue_context);
         if (result != 0)
         {