MONGOC_COLLECTION_COUNT_DOCUMENTS - Online Linux Manual Page
Section : 3 Updated : Feb 04, 2021 Source : 1.17.4 Note : libmongoc NAMEmongoc_collection_count_documents − mongoc_collection_count_documents()SYNOPSISint64_t
mongoc_collection_count_documents (mongoc_collection_t *collection,
const bson_t *filter,
const bson_t *opts,
const mongoc_read_prefs_t *read_prefs,
bson_t *reply,
bson_error_t *error);
PARAMETERS• collection: A mongoc_collection_t. • filter: A bson_t containing the filter. • opts: A bson_t, NULL to ignore. • read_prefs: A mongoc_read_prefs_t or NULL. • reply: A location for an uninitialized bson_t to store the command reply, NULL to ignore. If not NULL, reply will be initialized. • 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. Read concern requires MongoDB 3.2 or later, otherwise an error is returned. • 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. • 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. • 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. • skip: An int specifying how many documents matching the query should be skipped before counting. • limit: An int specifying the maximum number of documents to count. DESCRIPTIONThis functions executes a count query on collection. In contrast with mongoc_collection_estimated_document_count(), the count returned is guaranteed to be accurate. This function is considered a retryable read operation. Upon a transient error (a network error, errors due to replica set failover, etc.) the operation is safely retried once. If retryreads is false in the URI (see mongoc_uri_t) the retry behavior does not apply. ERRORSErrors are propagated via the error parameter. RETURNS−1 on failure, otherwise the number of documents counted. EXAMPLE#include <bson/bson.h>
#include <mongoc/mongoc.h>
#include <stdio.h>
static void
print_count (mongoc_collection_t *collection, bson_t *filter){
bson_error_t error;
int64_t count;
bson_t* opts = BCON_NEW ("skip", BCON_INT64(5));
count = mongoc_collection_count_documents (
collection, filter, opts, NULL, NULL, &error);
bson_destroy (opts);
if (count < 0){
fprintf (stderr, "Count failed: %s\n", error.message);
} else {
printf ("%" PRId64 " documents counted.\n", count);
}}MIGRATING FROM DEPRECATED COUNT FUNCTIONSWhen migrating to mongoc_collection_count_documents from the deprecated mongoc_collection_count or mongoc_collection_count_with_opts, the following query operators in the filter must be replaced: