Help Center/ Object Storage Migration Service/ API Reference/ APIs V2 (Recommended)/ Operations on Buckets/ Check Whether There Are Objects with a Specified Prefix in a Source Bucket
Updated on 2026-02-27 GMT+08:00

Check Whether There Are Objects with a Specified Prefix in a Source Bucket

Function

This API is used to check whether there are objects with a specified prefix in a source bucket.

Calling Method

For details, see Calling APIs.

Authorization Information

Each account has all the permissions required to call all APIs, but IAM users must be assigned the required permissions.

  • If you are using role/policy-based authorization, see Permissions Policies and Supported Actions for details on the required permissions.
  • If you are using identity policy-based authorization, the following identity policy-based permissions are required.

    Action

    Access Level

    Resource Type (*: required)

    Condition Key

    Alias

    Dependencies

    oms::checkBucketPrefix

    Read

    -

    -

    -

    -

URI

POST /v2/{project_id}/objectstorage/buckets/prefix

Table 1 Path Parameters

Parameter

Mandatory

Type

Description

project_id

Yes

String

The project ID.

Minimum: 1

Maximum: 1024

Request Parameters

Table 2 Request header parameters

Parameter

Mandatory

Type

Description

X-Auth-Token

Yes

String

The token used for IAM authentication. Ensure that the project ID in the token matches the project ID in the request URI.

Minimum: 1

Maximum: 16384

Table 3 Request body parameters

Parameter

Mandatory

Type

Description

cloud_type

Yes

String

The cloud service provider.

AWS: Amazon Web Services

Aliyun: Alibaba Cloud

Qiniu: Qiniu Cloud

QingCloud

Tencent: Tencent Cloud

Baidu: Baidu Cloud

KingsoftCloud

Azure: Microsoft Azure

UCloud

HuaweiCloud: Huawei Cloud

Google: Google Cloud

URLSource: URL data sources

HEC

Default: Aliyun

Minimum: 0

Maximum: 100

ak

No

String

The AK for accessing the source bucket. Enter a maximum of 100 characters. This parameter is mandatory when task_type is not url_list.

Minimum: 0

Maximum: 100

sk

No

String

The SK for accessing the destination bucket. Enter a maximum of 100 characters. This parameter is mandatory when task_type is not url_list.

Minimum: 0

Maximum: 100

json_auth_file

No

String

The file used for Google Cloud Storage authentication.

Minimum: 0

Maximum: 65535

connection_string

No

String

The connection string, which is used for Microsoft Azure Blob authentication.

Minimum: 0

Maximum: 2048

app_id

No

String

Tencent Cloud app ID. This parameter is mandatory when cloud_type is Tencent. You can obtain the value from the account information page on the Tencent Cloud console.

Minimum: 0

Maximum: 255

bucket_name

Yes

String

The bucket name.

Minimum: 0

Maximum: 100

file_name

Yes

String

The prefix.

Minimum: 0

Maximum: 1024

data_center

Yes

String

The data center region.

Minimum: 0

Maximum: 100

security_token

No

String

The security token.

Minimum: 0

Maximum: 16384

Response Parameters

Status code: 200

Table 4 Response body parameters

Parameter

Type

Description

exist

Boolean

Whether the prefix is found.

Default: false

Status code: 400

Table 5 Response body parameters

Parameter

Type

Description

error_msg

String

Error message.

error_code

String

Error code.

Example Requests

This example checks whether bucket xxx has objects with prefix xxxx.

POST https://{endpoint}/v2/{project_id}/objectstorage/buckets/prefix

{
  "cloud_type" : "HuaweiCloud",
  "ak" : "xxxxak",
  "sk" : "xxxxsk",
  "app_id" : "apptest123",
  "bucket_name" : "xxx",
  "file_name" : "xxxx",
  "data_center" : "cn-north-x",
  "security_token" : "string"
}

Example Responses

Status code: 200

The response body for verifying the prefix.

{
  "exist" : true
}

SDK Sample Code

The SDK sample code is as follows.

This example checks whether bucket xxx has objects with prefix xxxx.

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package com.huaweicloud.sdk.test;

import com.huaweicloud.sdk.core.auth.ICredential;
import com.huaweicloud.sdk.core.auth.BasicCredentials;
import com.huaweicloud.sdk.core.exception.ConnectionException;
import com.huaweicloud.sdk.core.exception.RequestTimeoutException;
import com.huaweicloud.sdk.core.exception.ServiceResponseException;
import com.huaweicloud.sdk.oms.v2.region.OmsRegion;
import com.huaweicloud.sdk.oms.v2.*;
import com.huaweicloud.sdk.oms.v2.model.*;


public class CheckPrefixSolution {

    public static void main(String[] args) {
        // The AK and SK used for authentication are hard-coded or stored in plaintext, which has great security risks. It is recommended that the AK and SK be stored in ciphertext in configuration files or environment variables and decrypted during use to ensure security.
        // In this example, AK and SK are stored in environment variables for authentication. Before running this example, set environment variables CLOUD_SDK_AK and CLOUD_SDK_SK in the local environment
        String ak = System.getenv("CLOUD_SDK_AK");
        String sk = System.getenv("CLOUD_SDK_SK");
        String projectId = "{project_id}";

        ICredential auth = new BasicCredentials()
                .withProjectId(projectId)
                .withAk(ak)
                .withSk(sk);

        OmsClient client = OmsClient.newBuilder()
                .withCredential(auth)
                .withRegion(OmsRegion.valueOf("<YOUR REGION>"))
                .build();
        CheckPrefixRequest request = new CheckPrefixRequest();
        CheckPrefixReq body = new CheckPrefixReq();
        body.withAppId("apptest123");
        body.withDataCenter("cn-north-x");
        body.withAk("xxxxak");
        body.withSk("xxxxsk");
        body.withBucketName("xxx");
        body.withFileName("xxxx");
        body.withSecurityToken("string");
        body.withCloudType("HuaweiCloud");
        request.withBody(body);
        try {
            CheckPrefixResponse response = client.checkPrefix(request);
            System.out.println(response.toString());
        } catch (ConnectionException e) {
            e.printStackTrace();
        } catch (RequestTimeoutException e) {
            e.printStackTrace();
        } catch (ServiceResponseException e) {
            e.printStackTrace();
            System.out.println(e.getHttpStatusCode());
            System.out.println(e.getRequestId());
            System.out.println(e.getErrorCode());
            System.out.println(e.getErrorMsg());
        }
    }
}

This example checks whether bucket xxx has objects with prefix xxxx.

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# coding: utf-8

import os
from huaweicloudsdkcore.auth.credentials import BasicCredentials
from huaweicloudsdkoms.v2.region.oms_region import OmsRegion
from huaweicloudsdkcore.exceptions import exceptions
from huaweicloudsdkoms.v2 import *

if __name__ == "__main__":
    # The AK and SK used for authentication are hard-coded or stored in plaintext, which has great security risks. It is recommended that the AK and SK be stored in ciphertext in configuration files or environment variables and decrypted during use to ensure security.
    # In this example, AK and SK are stored in environment variables for authentication. Before running this example, set environment variables CLOUD_SDK_AK and CLOUD_SDK_SK in the local environment
    ak = os.environ["CLOUD_SDK_AK"]
    sk = os.environ["CLOUD_SDK_SK"]
    projectId = "{project_id}"

    credentials = BasicCredentials(ak, sk, projectId)

    client = OmsClient.new_builder() \
        .with_credentials(credentials) \
        .with_region(OmsRegion.value_of("<YOUR REGION>")) \
        .build()

    try:
        request = CheckPrefixRequest()
        request.body = CheckPrefixReq(
            app_id="apptest123",
            data_center="cn-north-x",
            ak="xxxxak",
            sk="xxxxsk",
            bucket_name="xxx",
            file_name="xxxx",
            security_token="string",
            cloud_type="HuaweiCloud"
        )
        response = client.check_prefix(request)
        print(response)
    except exceptions.ClientRequestException as e:
        print(e.status_code)
        print(e.request_id)
        print(e.error_code)
        print(e.error_msg)

This example checks whether bucket xxx has objects with prefix xxxx.

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package main

import (
	"fmt"
	"github.com/huaweicloud/huaweicloud-sdk-go-v3/core/auth/basic"
    oms "github.com/huaweicloud/huaweicloud-sdk-go-v3/services/oms/v2"
	"github.com/huaweicloud/huaweicloud-sdk-go-v3/services/oms/v2/model"
    region "github.com/huaweicloud/huaweicloud-sdk-go-v3/services/oms/v2/region"
)

func main() {
    // The AK and SK used for authentication are hard-coded or stored in plaintext, which has great security risks. It is recommended that the AK and SK be stored in ciphertext in configuration files or environment variables and decrypted during use to ensure security.
    // In this example, AK and SK are stored in environment variables for authentication. Before running this example, set environment variables CLOUD_SDK_AK and CLOUD_SDK_SK in the local environment
    ak := os.Getenv("CLOUD_SDK_AK")
    sk := os.Getenv("CLOUD_SDK_SK")
    projectId := "{project_id}"

    auth := basic.NewCredentialsBuilder().
        WithAk(ak).
        WithSk(sk).
        WithProjectId(projectId).
        Build()

    client := oms.NewOmsClient(
        oms.OmsClientBuilder().
            WithRegion(region.ValueOf("<YOUR REGION>")).
            WithCredential(auth).
            Build())

    request := &model.CheckPrefixRequest{}
	appIdCheckPrefixReq:= "apptest123"
	akCheckPrefixReq:= "xxxxak"
	skCheckPrefixReq:= "xxxxsk"
	securityTokenCheckPrefixReq:= "string"
	request.Body = &model.CheckPrefixReq{
		AppId: &appIdCheckPrefixReq,
		DataCenter: "cn-north-x",
		Ak: &akCheckPrefixReq,
		Sk: &skCheckPrefixReq,
		BucketName: "xxx",
		FileName: "xxxx",
		SecurityToken: &securityTokenCheckPrefixReq,
		CloudType: "HuaweiCloud",
	}
	response, err := client.CheckPrefix(request)
	if err == nil {
        fmt.Printf("%+v\n", response)
    } else {
        fmt.Println(err)
    }
}

For SDK sample code of more programming languages, see the Sample Code tab in API Explorer. SDK sample code can be automatically generated.

Status Codes

Status Code

Description

200

The response body for verifying the prefix.

400

Standard error response.

Error Codes

See Error Codes.