---
name: "mongoc_find_and_modify_opts_set_fields"
section: "3"
platform: "linux"
package: "libmongoc-doc"
version: "1.30.4-1+deb13u3"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/mongoc_find_and_modify_opts_set_fields"
---

# mongoc\_find\_and\_modify\_opts\_set\_fields(3)

## SYNOPSIS

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

## 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.

**fields** does not have to remain valid after calling this function.

## RETURNS

Returns **true** if it successfully added the option to the builder, otherwise **false**.

## SETTING FIELDS

fields.c

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

## AUTHOR

MongoDB, Inc

## COPYRIGHT

2009-present, MongoDB, Inc.