mongoc_collection_update_one() — MongoDB C Driver 1.9.2

- MongoDB C Driver 1.9.2 »
- API Reference »
- mongoc_collection_t

# mongoc_collection_update_one()

## 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.
- `opts`: A `bson_t` containing additional options or `NULL`.
- `reply`: Optional. An uninitialized `bson_t` populated with the update result, or `NULL`.
- `error`: An optional location for a bson_error_t or `NULL`.

`opts` may be NULL or a BSON document with additional command options:

- `readConcern`: Construct a mongoc_read_concern_t and use mongoc_read_concern_append() to add the read concern to `opts`. See the example code for mongoc_client_read_command_with_opts().
- `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`: Construct a mongoc_client_session_t with mongoc_client_start_session() and use mongoc_client_session_append() to add the session to `opts`. See the example code for mongoc_client_session_t.
- `validate`: Set to `false` to skip client-side validation of the provided BSON documents.
- `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.
- `serverId`: To target a specific server, include an int32 “serverId” field. Obtain the id by calling mongoc_client_select_server(), then mongoc_server_description_id() on its return value.
- `arrayFilters` An array of filters specifying to which array elements an update should apply.
- `upsert` A `boolean`, when true, creates a new document if no document matches the query.

## 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 “modifiedCount” and “matchedCount”. If a document was upserted, `reply` contains an “upsertedId” field. 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()`.

## See Also

MongoDB update command documentation for more information on the update options.

mongoc_collection_update_many()

mongoc_collection_replace_one()

## 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.

If provided, `reply` will be initialized and populated with the fields `matchedCount`, `modifiedCount`, and optionally `upsertedId` if applicable.

## Example

example-update.c

    #include "mongoc.h"

    int
    main (int argc, char **argv)
    {
       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 err = {0};
       mongoc_cursor_t *cursor;
       mongoc_client_t *client =
          mongoc_client_new ("mongodb://localhost:27017/?appname=example-update");
       mongoc_collection_t *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, &err)) {
          fprintf (stderr, "insert failed: %s\n", err.message);
          return EXIT_FAILURE;
       }

       if (!mongoc_collection_update_one (
              coll, selector, update, NULL, NULL, &err)) {
          fprintf (stderr, "update failed %s\n", err.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_client_destroy (client);
       return EXIT_SUCCESS;
    }

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