tencent cloud

Overview

This document provides an overview of the API and sample code for quickly checking whether an object exists in a bucket.

Checking Whether an Object Exists

Description

This API is used to check whether an object exists in a bucket. It actually calls the HEAD Object API to perform the action.

Method prototype

cos_status_t *cos_check_object_exist(const cos_request_options_t *options, 
                                   const cos_string_t *bucket, 
                                   const cos_string_t *object,
                                   cos_table_t *headers, 
                                   cos_object_exist_status_e *object_exist,
                                   cos_table_t **resp_headers);

Parameter description

Response description

Sample

#include "cos_http_io.h"
#include "cos_api.h"
#include "cos_log.h"
// `endpoint` is the COS access domain name. For more information, see https://intl.cloud.tencent.com/document/product/436/6224.
static char TEST_COS_ENDPOINT[] = "cos.ap-guangzhou.myqcloud.com";
// A developer-owned secret ID/key used for the project. It can be obtained at https://console.cloud.tencent.com/cam/capi.
static char *TEST_ACCESS_KEY_ID;                // Your SecretId
static char *TEST_ACCESS_KEY_SECRET;            // Your SecretKey
// A unique user-level resource identifier for COS access. It can be obtained at https://console.cloud.tencent.com/cam/capi.
static char TEST_APPID[] = "<APPID>";    // Your APPID
// COS bucket name, in the format of [bucket]-[appid], for example `mybucket-1253666666`. It can be obtained at https://console.cloud.tencent.com/cos5/bucket.
static char TEST_BUCKET_NAME[] = "<bucketname-appid>";  
// A unique identifier of an object stored in COS. For more information about objects and object keys, please see https://intl.cloud.tencent.com/document/product/436/13324.
static char TEST_OBJECT_NAME1[] = "1.txt";
void log_status(cos_status_t *s)
{
  cos_warn_log("status->code: %d", s->code);
  if (s->error_code) cos_warn_log("status->error_code: %s", s->error_code);
  if (s->error_msg) cos_warn_log("status->error_msg: %s", s->error_msg);
  if (s->req_id) cos_warn_log("status->req_id: %s", s->req_id);
}
void init_test_config(cos_config_t *config, int is_cname)
{
  cos_str_set(&config->endpoint, TEST_COS_ENDPOINT);
  cos_str_set(&config->access_key_id, TEST_ACCESS_KEY_ID);
  cos_str_set(&config->access_key_secret, TEST_ACCESS_KEY_SECRET);
  cos_str_set(&config->appid, TEST_APPID);
  config->is_cname = is_cname;
}
void init_test_request_options(cos_request_options_t *options, int is_cname)
{
  options->config = cos_config_create(options->pool);
  init_test_config(options->config, is_cname);
  options->ctl = cos_http_controller_create(options->pool, 0);
}
void test_check_object_exist()
{
  cos_pool_t *p = NULL;
  int is_cname = 0;
  cos_status_t *s = NULL;
  cos_request_options_t *options = NULL;
  cos_string_t bucket;
  cos_string_t object;
  cos_table_t *resp_headers;
  cos_table_t *headers = NULL;
  cos_object_exist_status_e object_exist;
   cos_pool_create(&p, NULL);
  options = cos_request_options_create(p);
  init_test_request_options(options, is_cname);
  cos_str_set(&bucket, TEST_BUCKET_NAME);
  cos_str_set(&object, TEST_OBJECT_NAME1);
   // Check whether an object exists
  s = cos_check_object_exist(options, &bucket, &object, headers, &object_exist, &resp_headers);
  if (object_exist == COS_OBJECT_NON_EXIST) {
      printf("object: %.*s non exist.\n", object.len, object.data);
  } else if (object_exist == COS_OBJECT_EXIST) {
      printf("object: %.*s exist.\n", object.len, object.data);
  } else {
      printf("object: %.*s unknown status.\n", object.len, object.data);
      log_status(s);
  }
   cos_pool_destroy(p);
}
int main(int argc, char *argv[])
{
  // Get SecretId and SecretKey from environment variables
  TEST_ACCESS_KEY_ID     = getenv("COS_SECRETID");
  TEST_ACCESS_KEY_SECRET = getenv("COS_SECRETKEY");
    if (cos_http_io_initialize(NULL, 0) != COSE_OK) {
     exit(1);
  }
   // Set the log level. Default value: `COS_LOG_WARN`
  cos_log_set_level(COS_LOG_WARN);
   // Set log output. Default value: `stderr`
  cos_log_set_output(NULL);
   test_check_object_exist();
   cos_http_io_deinitialize();
   return 0;
}