example for ignoring "ns not found" error

Author: ajdavis

src/libmongoc/doc/mongoc_collection_drop_with_opts.rst

@@ -30,6 +30,35 @@ This function requests that a ``collection`` be dropped, including all indexes a
 
 If no write concern is provided in ``opts``, the collection's write concern is used.
 
+If the collection does not exist, the server responds with an "ns not found" error. It is safe to ignore this error; set the :ref:`Error API Version <error_api_version>` to 2 and ignore server error code 26:
+
+.. code-block:: c
+
+  mongoc_client_t *client;
+  mongoc_collection_t *collection;
+  bson_error_t error;
+  bool r;
+
+  client = mongoc_client_new (NULL);
+  mongoc_client_set_error_api (client, 2);
+  collection = mongoc_client_get_collection (client, "db", "collection");
+  r = mongoc_collection_drop_with_opts (collection, NULL /* opts */, &error);
+  if (r) {
+     printf ("Dropped.\n");
+  } else {
+     printf ("Error message: %s\n", error.message);
+     if (error.domain == MONGOC_ERROR_SERVER && error.code == 26) {
+        printf ("Ignoring 'ns not found' error\n");
+     } else {
+        fprintf (stderr, "Unrecognized error!\n");
+     }
+  }
+
+  mongoc_collection_destroy (collection);
+  mongoc_client_destroy (client);
+
+In MongoDB 3.0 and older, the "ns not found" error code is the generic MONGOC_ERROR_QUERY_FAILURE; in this case check whether the error message is equal to the string "ns not found".
+
 Errors
 ------