Updated on 2026-08-03 GMT+08:00

Obtaining Object Tags (SDK for C)

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Function

This API is used to obtain the tags of an object.

Restrictions

Method

void get_object_tagging(const obs_options *options, const char *key,
                       obs_get_object_tagging_handler *handler, void *callback_data);

Request Parameters

Table 1 List of request parameters

Parameter

Type

Mandatory (Yes/No)

Description

options

const obs_options*

Yes

Explanation:

Context of the requested bucket. You can set the AK, SK, endpoint, bucket, timeout interval, and temporary credentials through obs_options.

Restrictions:

None

Value range:

None

Default value:

None

key

char *

Yes

Explanation:

Object name. An object name is a complete path of the object that does not contain the bucket name.

For example, if the address for accessing the object is examplebucket.obs.ap-southeast-1.myhuaweicloud.com/folder/test.txt, the object name is folder/test.txt.

Restrictions:

The name of each object in a bucket must be unique.

Value range:

The value can contain 1 to 1,024 characters.

Default value:

None

handler

obs_get_object_tagging_handler *

Yes

Explanation:

A callback structure where all members are pointers to callback functions, used to set the callback functions that handle response data. You can set a callback function to copy the response data from the server to callback_data (custom callback data).

Restrictions:

None

Value range:

None

Default value:

None

callback_data

void *

No

Explanation:

Custom callback data.

Restrictions:

None

Value range:

None

Default value:

None

Table 2 obs_get_object_tagging_handler

Parameter

Type

Mandatory (Yes/No)

Description

response_handler

obs_response_handler*

Yes

Explanation:

Response callback function structure.

Restrictions:

None

Value range:

None

Default value:

None

get_object_tagging_callback

obs_get_object_tagging_callback *

Yes

Explanation:

The callback function pointer tag. The content of tagging_count and tagging_list in the callback can be recorded in callback_data (custom callback data).

Restrictions:

None

Value range:

None

Default value:

None

Table 3 obs_get_object_tagging_callback

Parameter

Type

Mandatory (Yes/No)

Description

tagging_list

obs_name_value*

Yes

Explanation:

Tag list.

Restrictions:

None

Value range:

None

Default value:

None

tag_number

unsigned int

Yes

Explanation:

Number of tags.

Restrictions:

None

Value range:

[0, 10]

Default value:

None

callback_data

void *

Yes

Explanation:

Pointer to the custom callback data.

Restrictions:

None

Value range:

None

Default value:

None

Table 4 obs_name_value

Parameter

Type

Mandatory (Yes/No)

Description

name

char *

Yes if used as a request parameter

Explanation:

Tag key.

Restrictions:

  • The tag key in the same bucket must be unique.
  • You can define tags or select the ones predefined on TMS.
  • A tag key must contain 1 to 128 characters.
  • Tag keys cannot start or end with a space and cannot contain commas (,), asterisks (*), vertical bars (|), slashes (/), less-than signs (<), greater-than signs (>), equal signs (=), backslashes (\), or ASCII control characters (0x00 to 0x1F). Tag keys and values must be URL encoded before being sent to a server.
  • A tag key is case-sensitive.

Default value:

None

Value range:

None

Default value:

None

value

char *

Yes if used as a request parameter

Explanation:

Tag value.

Restrictions:

Tag values can be duplicated or left blank.

  • A tag value must contain 0 to 255 characters.
  • Tag values cannot start or end with a space and cannot contain commas (,), asterisks (*), vertical bars (|), slashes (/), less-than signs (<), greater-than signs (>), equal signs (=), backslashes (\), or ASCII control characters (0x00 to 0x1F). Tag keys and values must be URL encoded before being sent to a server.
  • A tag value is case-sensitive.

Default value:

None

Value range:

None

Default value:

None

Sample Code

This example obtains the object tags.
#include "eSDKOBS.h"
#include <stdio.h>
// The response callback function. The content of properties in the callback can be recorded in callback_data (custom callback data).
obs_status response_properties_callback(const obs_response_properties *properties, void *callback_data);
// The callback function for the completed response. The content of obs_status and obs_error_details in the callback can be recorded in callback_data (custom callback data).
void response_complete_callback(obs_status status, const obs_error_details *error, void *callback_data);
obs_status get_object_tagging_callback(int tagging_count, obs_name_value *tagging_list, void *callback_data);
typedef struct tagkv
{
    char key[250];
    char value[250];
}tagkv;
typedef struct TaggingInfo
{
    int tagCount;
    tagkv taglist[10];
    obs_status ret_status;
}TaggingInfo;
int main()
{
    // The following example shows how to use get_object_tagging to obtain object tags:
    // Call the obs_initialize method at the program entry to initialize global resources such as the network and memory.
    obs_initialize(OBS_INIT_ALL);
    obs_options options;
    // Create and initialize options, including the access domain name (host_name), access keys (access_key_id and access_key_secret), bucket name (bucket_name), and bucket storage class (storage_class).
    init_obs_options(&options);
    // Enter the endpoint corresponding to the bucket for host_name. CN-Hong Kong is used here as an example. Replace it with the one currently in use.
    options.bucket_options.host_name = "obs.ap-southeast-1.myhuaweicloud.com";
    // Hard-coded or plaintext AK and SK are risky. For security purposes, encrypt your AK and SK and store them in the configuration file or environment variables.
    // In this example, the AK and SK are stored in environment variables for identity authentication. Before running the code in this example, configure local environment variables ACCESS_KEY_ID and SECRET_ACCESS_KEY.
    options.bucket_options.access_key = getenv("ACCESS_KEY_ID");
    options.bucket_options.secret_access_key = getenv("SECRET_ACCESS_KEY");
    // Specify the bucket name, for example, example-bucket-name.
    char * bucketName = "example-bucket-name";
    options.bucket_options.bucket_name = bucketName;
    obs_response_handler response_handler = { &response_properties_callback, &response_complete_callback };
    // Set the response callback function.
    obs_get_object_tagging_handler get_object_tagging_handler =
    {
        response_handler,
        &get_object_tagging_callback
    };
    // Create callback data.
    TaggingInfo tagging_info;
    memset(&tagging_info, 0, sizeof(TaggingInfo));
    tagging_info.ret_status = OBS_STATUS_BUTT;
    // Obtain object tags.
    get_object_tagging(&options, "objectname", &get_object_tagging_handler, &tagging_info);
    if (OBS_STATUS_OK == tagging_info.ret_status) {
        printf("get object tagging successfully.\n");
    }
    else
    {
        printf("get object tagging failed(%s).\n", obs_get_status_name(tagging_info.ret_status));
    }
    // Release the allocated global resources.
    obs_deinitialize();
}
void printTagInfo(TaggingInfo* infoToPrint)
{
    int i;
    printf("tag number is %d\n", infoToPrint->tagCount);
    for (i = 0; i < infoToPrint->tagCount; i++)
    {
        printf("key:[%s], value[%s]\n", infoToPrint->taglist[i].key, infoToPrint->taglist[i].value);
    }
}
obs_status get_object_tagging_callback(int tagging_count, obs_name_value *tagging_list, void *callback_data)
{
    int tag_num = 0;
    TaggingInfo * tag_info = (TaggingInfo *)callback_data;
    tag_info->tagCount = tagging_count;
    if (tagging_count > 0)
    {
        for (tag_num = 0; tag_num < tagging_count; tag_num++)
        {
            memcpy_s(tag_info->taglist[tag_num].key, sizeof(tag_info->taglist[tag_num].key), (&tagging_list[tag_num])->name, strlen((&tagging_list[tag_num])->name) + 1);
            memcpy_s(tag_info->taglist[tag_num].value, sizeof(tag_info->taglist[tag_num].value), (&tagging_list[tag_num])->value, strlen((&tagging_list[tag_num])->value) + 1);
        }
    }
    printTagInfo(tag_info);
    return OBS_STATUS_OK;
}
// The response callback function. The content of properties in the callback can be recorded in callback_data (custom callback data).
obs_status response_properties_callback(const obs_response_properties *properties, void *callback_data)
{
    if (properties == NULL)
    {
        printf("error! obs_response_properties is null!");
        return OBS_STATUS_OK;
    }
    // Print the response.
#define print_nonnull(name, field)                                 \
    do {                                                           \
        if (properties-> field) {                                  \
            printf("%s: %s\n", name, properties->field);          \
        }                                                          \
    } while (0)
    print_nonnull("request_id", request_id);
    print_nonnull("request_id2", request_id2);
    print_nonnull("content_type", content_type);
    if (properties->content_length) {
        printf("content_length: %llu\n", properties->content_length);
    }
    print_nonnull("server", server);
    print_nonnull("ETag", etag);
    print_nonnull("version_id", version_id);
    return OBS_STATUS_OK;
}
// The callback function for the completed response. The content of obs_status and obs_error_details in the callback can be recorded in callback_data (custom callback data).
void response_complete_callback(obs_status status, const obs_error_details *error, void *callback_data)
{
    if (callback_data) {
        TaggingInfo *taggingInfo = (TaggingInfo *)callback_data;
        taggingInfo->ret_status = status;
    }
    else {
        printf("Callback_data is NULL");
    }
    if (error && error->message) {
        printf("Error Message: \n   %s\n", error->message);
    }
    if (error && error->resource) {
        printf("Error Resource: \n  %s\n", error->resource);
    }
    if (error && error->further_details) {
        printf("Error further_details: \n   %s\n", error->further_details);
    }
    if (error && error->extra_details_count) {
        int i;
        for (i = 0; i < error->extra_details_count; i++) {
            printf("Error Extra Detail(%d):\n   %s:%s\n", i, error->extra_details[i].name,
                error->extra_details[i].value);
        }
    }
    if (error && error->error_headers_count) {
        int i;
        for (i = 0; i < error->error_headers_count; i++) {
            const char *errorHeader = error->error_headers[i];
            printf("Error Headers(%d):\n    %s\n", i, errorHeader == NULL ? "NULL Header" : errorHeader);
        }
    }
}