---
name: "mongoc_collection_update_one"
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_collection_update_one"
---

# mongoc\_collection\_update\_one(3)

## 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* containing the query to match the document for updating.

- •

  **update**: A *bson\_t* containing the update to perform. If updating with a pipeline, a *bson\_t* array.

- •

  **reply**: A maybe-**NULL** pointer to *overwritable storage* for a *bson\_t* 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*. Set to **false** to skip client-side validation of the provided BSON documents.

- •

  **comment**: A *bson\_value\_t* 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*, and *the MongoDB Manual entry on 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()*.

## 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 for more information on the update options.
```

```
mongoc_collection_update_many()
```

```
mongoc_collection_replace_one()
```

## AUTHOR

MongoDB, Inc

## COPYRIGHT

2009-present, MongoDB, Inc.