mongoc_find_and_modify_opts_set_fields()

Synopsis

bool
mongoc_find_and_modify_opts_set_fields (mongoc_find_and_modify_opts_t  *opts,
                                        const bson_t                   *fields);

New in mongoc 1.3.0

Parameters

opts	A mongoc_find_and_modify_opts_t.
fields	A subset of fields to return. Choose which fields to include by appending {fieldname: 1} for each fieldname, or excluding it with {fieldname: 0}.

Description

Adds fields argument to the builder.

Returns

Returns true if it successfully added the option to the builder.

Setting fields

void fam_fields(mongoc_collection_t *collection)
{
   mongoc_find_and_modify_opts_t *opts;
   bson_t fields = BSON_INITIALIZER;
   bson_t *update;
   bson_t reply;
   bson_error_t error;
   bson_t query = BSON_INITIALIZER;
   bool success;


   /* Find Zlatan Ibrahimovic */
   BSON_APPEND_UTF8 (&query, "lastname", "Ibrahimovic");
   BSON_APPEND_UTF8 (&query, "firstname", "Zlatan");

   /* Return his goal tally */
   BSON_APPEND_INT32 (&fields, "goals", 1);

   /* Bump his goal tally */
   update = BCON_NEW ("$inc", "{",
      "goals", BCON_INT32 (1),
   "}");

   opts = mongoc_find_and_modify_opts_new ();
   mongoc_find_and_modify_opts_set_update (opts, update);
   mongoc_find_and_modify_opts_set_fields (opts, &fields);
   /* Return the new tally */
   mongoc_find_and_modify_opts_set_flags (opts, MONGOC_FIND_AND_MODIFY_RETURN_NEW);

   success = mongoc_collection_find_and_modify_with_opts (collection, &query, opts, &reply, &error);

   if (success) {
      char *str;

      str = bson_as_json (&reply, NULL);
      printf ("%s\n", str);
      bson_free (str);
   } else {
      fprintf(stderr, "Got error: \"%s\" on line %d\n", error.message, __LINE__);
   }

   bson_destroy (&reply);
   bson_destroy (update);
   bson_destroy (&fields);
   bson_destroy (&query);
   mongoc_find_and_modify_opts_destroy (opts);
}

Outputs:

{
    "lastErrorObject": {
        "updatedExisting": true,
        "n": 1
    },
    "value": {
        "_id": {
            "$oid": "56562a99d13e6d86239c7b00"
        },
        "goals": 343
    },
    "ok": 1
}