Provided by: libmongoc-doc_2.2.1-1_all 
SYNOPSIS
bool
mongoc_collection_update_one (mongoc_collection_t *collection,
const bson_t *selector,
const bson_t *update,
const bson_t *opts,
bson_t *reply,
bson_error_t *error);
PARAMETERS
• collection: A mongoc_collection_t <>.
• selector: A bson_t <https://www.mongoc.org/libbson/current/bson_t.html> containing the query to match
the document for updating.
• update: A bson_t <https://www.mongoc.org/libbson/current/bson_t.html> containing the update to perform.
If updating with a pipeline, a bson_t <https://www.mongoc.org/libbson/current/bson_t.html> array.
• reply: A maybe-NULL pointer to overwritable storage <https://www.mongodb.com/docs/languages/c/c-driver/
current/libbson/guides/lifetimes/#overwritable-storage> for a bson_t <https://www.mongoc.org/libbson/
current/bson_t.html> to contain the results.
• error: An optional location for a bson_error_t <> or NULL.
opts may be NULL or a BSON document with additional command options:
• writeConcern: Construct a mongoc_write_concern_t <> and use mongoc_write_concern_append() <> to add the
write concern to opts. See the example code for mongoc_client_write_command_with_opts() <>.
• sessionId: First, construct a mongoc_client_session_t <> with mongoc_client_start_session() <>. You can
begin a transaction with mongoc_client_session_start_transaction() <>, optionally with a
mongoc_transaction_opt_t <> that overrides the options inherited from collection, and use
mongoc_client_session_append() <> to add the session to opts. See the example code for
mongoc_client_session_t <>.
• validate: Construct a bitwise-or of all desired bson_validate_flags_t <https://www.mongoc.org/libbson/
current/bson_validate_flags_t.html>. Set to false to skip client-side validation of the provided BSON
documents.
• comment: A bson_value_t <https://www.mongoc.org/libbson/current/bson_value_t.html> specifying the
comment to attach to this command. The comment will appear in log messages, profiler output, and
currentOp output. Requires MongoDB 4.4 or later.
• bypassDocumentValidation: Set to true to skip server-side schema validation of the provided BSON
documents.
• collation: Configure textual comparisons. See Setting Collation Order <https://www.mongodb.com/docs/
languages/c/c-driver/current/libmongoc/guides/bulk/#setting-collation-order>, and the MongoDB Manual
entry on Collation <https://www.mongodb.com/docs/manual/reference/collation/>. Collation requires
MongoDB 3.2 or later, otherwise an error is returned.
• hint: A document or string that specifies the index to use to support the query predicate.
• upsert: When true, creates a new document if no document matches the query.
• let: A BSON document consisting of any number of parameter names, each followed by definitions of
constants in the MQL Aggregate Expression language.
• arrayFilters: An array of filters specifying to which array elements an update should apply.
• sort: Specify a sort order when matching documents.
DESCRIPTION
This function updates at most one document in collection that matches selector.
To update multiple documents see mongoc_collection_update_many() <>.
If you pass a non-NULL reply, it is filled out with fields matchedCount, modifiedCount, and optionally
upsertedId if applicable. If there is a server error then reply contains either a "writeErrors" array
with one subdocument or a "writeConcernErrors" array. The reply must be freed with bson_destroy()
<https://www.mongoc.org/libbson/current/bson_destroy.html>.
ERRORS
Errors are propagated via the error parameter.
RETURNS
Returns true if successful. Returns false and sets error if there are invalid arguments or a server or
network error.
A write concern timeout or write concern error is considered a failure.
EXAMPLE
example-update.c
#include <mongoc/mongoc.h>
int
main(void)
{
mongoc_init();
bson_t *to_insert = BCON_NEW("_id", BCON_INT32(1));
bson_t *selector = BCON_NEW("_id", "{", "$gt", BCON_INT32(0), "}");
bson_t *update = BCON_NEW("$set", "{", "x", BCON_INT32(1), "}");
const bson_t *next_doc;
char *to_str;
bson_error_t error = {0};
mongoc_cursor_t *cursor;
mongoc_client_t *client;
mongoc_collection_t *coll;
const char *uri_string = "mongodb://localhost:27017/?appname=example-update";
mongoc_uri_t *uri = mongoc_uri_new_with_error(uri_string, &error);
if (!uri) {
fprintf(stderr,
"failed to parse URI: %s\n"
"error message: %s\n",
uri_string,
error.message);
return EXIT_FAILURE;
}
client = mongoc_client_new_from_uri(uri);
if (!client) {
return EXIT_FAILURE;
}
coll = mongoc_client_get_collection(client, "db", "example_coll");
mongoc_client_set_error_api(client, 2);
/* insert a document */
if (!mongoc_collection_insert_one(coll, to_insert, NULL, NULL, &error)) {
fprintf(stderr, "insert failed: %s\n", error.message);
return EXIT_FAILURE;
}
if (!mongoc_collection_update_one(coll, selector, update, NULL, NULL, &error)) {
fprintf(stderr, "update failed: %s\n", error.message);
return EXIT_FAILURE;
}
to_str = bson_as_relaxed_extended_json(to_insert, NULL);
printf("inserted: %s\n", to_str);
bson_free(to_str);
cursor = mongoc_collection_find_with_opts(coll, selector, NULL, NULL);
BSON_ASSERT(mongoc_cursor_next(cursor, &next_doc));
printf("after update, collection has the following document:\n");
to_str = bson_as_relaxed_extended_json(next_doc, NULL);
printf("%s\n", to_str);
bson_free(to_str);
BSON_ASSERT(mongoc_collection_drop(coll, NULL));
bson_destroy(to_insert);
bson_destroy(update);
bson_destroy(selector);
mongoc_collection_destroy(coll);
mongoc_uri_destroy(uri);
mongoc_client_destroy(client);
mongoc_cleanup();
return EXIT_SUCCESS;
}
See also:
MongoDB update command documentation <https://www.mongodb.com/docs/manual/reference/command/update/> for more information on the update options.
mongoc_collection_update_many() <>
mongoc_collection_replace_one() <>
Author
MongoDB, Inc
Copyright
2009-present, MongoDB, Inc.
2.2.1 Dec 11, 2025 MONGOC_COLLECTION_UPDATE_ONE(3)