Object Storage Service:Conditional download in PHP

Usage notes

• In this topic, the public endpoint of the China (Hangzhou) region is used. If you want to access OSS from other Alibaba Cloud services in the same region as OSS, use an internal endpoint. For more information about OSS regions and endpoints, see Regions, endpoints and open ports.

• In this topic, an OSSClient instance is created by using an OSS endpoint. If you want to create an OSSClient instance by using custom domain names or Security Token Service (STS), see Create an OSSClient instance.

• To perform conditional download, you must have the oss:GetObject permission. For more information, see Attach a custom policy to a RAM user.

Conditions

The following table describes conditions that OSS supports and you can specify when you use conditional download. You can use If-Modified-Since and If-Unmodified-Since as object download conditions at the same time. You can use If-Match and If-None-Match as object download conditions at the same time.

Download an object to your local memory by using conditional download

The following code provides an example on how to specify conditions and download the object that matches the conditions to your local memory:

<?php
if (is_file(__DIR__ . '/../autoload.php')) {
    require_once __DIR__ . '/../autoload.php';
}
if (is_file(__DIR__ . '/../vendor/autoload.php')) {
    require_once __DIR__ . '/../vendor/autoload.php';
}
use OSS\Credentials\EnvironmentVariableCredentialsProvider;
use OSS\OssClient;

// Obtain access credentials from environment variables. Before you run the sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are configured.  
$provider = new EnvironmentVariableCredentialsProvider();
// In this example, the endpoint of the China (Hangzhou) region is used. Specify your actual endpoint. 
$endpoint = "http://oss-cn-hangzhou.aliyuncs.com";
// Specify the bucket name. 
$bucket= "yourBucketName";
// Specify the object name. The object name is the full path of the object. The path of the object cannot contain the bucket name. Example: exampledir/exampleobject.txt. 
$object = "yourObjectName";

try{
    $options = array(
        OssClient::OSS_HEADERS => array(          
          // Set If-Modified-Since to 14:47:53 Friday, April 9, 2021 in GMT. 
          OssClient::OSS_IF_MODIFIED_SINCE => "Fri, 9 Apr 2021 14:47:53 GMT",
          // Set If-Unmodified-Since to 14:47:53 Wednesday, October 13, 2021 in GMT. 
          OssClient::OSS_IF_UNMODIFIED_SINCE => "Fri, 13 Oct 2021 14:47:53 GMT",
          // Specify that objects whose ETag values do not match the ETag values that are specified in the requests are downloaded. 
          OssClient::OSS_IF_NONE_MATCH => '"5B3C1A2E0563E1B002CC607C****"',
          // Specify that objects whose ETag values match the ETag values that are specified in the requests are downloaded. 
          OssClient::OSS_IF_MATCH => '"fba9dede5f27731c9771645a3986****"',
        )

    );

    $config = array(
        "provider" => $provider,
        "endpoint" => $endpoint,
        "signatureVersion" => OssClient::OSS_SIGNATURE_VERSION_V4,
        "region"=> "cn-hangzhou"
    );
    $ossClient = new OssClient($config);
    // Download the object to your local memory. 
    $content = $ossClient->getObject($bucket, $object, $options);
} catch(OssException $e) {
    printf(__FUNCTION__ . ": FAILED\n");
    printf($e->getMessage() . "\n");
    return;
}
print ($content);
print(__FUNCTION__ . ": OK" . "\n");

Download an object to a local file by using conditional download

The following code provides an example on how to specify conditions and download the object that matches the conditions to a local file:

<?php
if (is_file(__DIR__ . '/../autoload.php')) {
    require_once __DIR__ . '/../autoload.php';
}
if (is_file(__DIR__ . '/../vendor/autoload.php')) {
    require_once __DIR__ . '/../vendor/autoload.php';
}
use OSS\Credentials\EnvironmentVariableCredentialsProvider;
use OSS\OssClient;

// Obtain access credentials from environment variables. Before you run the sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are configured.  
$provider = new EnvironmentVariableCredentialsProvider();
// In this example, the endpoint of the China (Hangzhou) region is used. Specify your actual endpoint. 
$endpoint = "http://oss-cn-hangzhou.aliyuncs.com";
// Specify the bucket name. 
$bucket= "yourBucketName";
// Specify the object name. The object name is the full path of the object. The path of the object cannot contain the bucket name. Example: exampledir/exampleobject.txt. 
$object = "yourObjectName";
// Specify the full path of the local object that you want to upload. Example: D:\\localpath\\examplefile.txt. 
$localfile = "yourLocalFile";

try{
    $options = array(
        OssClient::OSS_HEADERS => array(          
           // Set If-Modified-Since to 14:47:53 Friday, April 9, 2021 in GMT. 
          OssClient::OSS_IF_MODIFIED_SINCE => "Fri, 9 Apr 2021 14:47:53 GMT",
          // Set If-Unmodified-Since to 14:47:53 Wednesday, October 13, 2021 in GMT. 
          OssClient::OSS_IF_UNMODIFIED_SINCE => "Fri, 13 Oct 2021 14:47:53 GMT",
          // Specify that objects whose ETag values do not match the ETag values that are specified in the requests are downloaded. 
          OssClient::OSS_IF_NONE_MATCH => '"5B3C1A2E0563E1B002CC607C****"',
          // Specify that objects whose ETag values match the ETag values that are specified in the requests are downloaded. 
          OssClient::OSS_IF_MATCH => '"fba9dede5f27731c9771645a3986****"',          
          OssClient::OSS_FILE_DOWNLOAD => $localfile
        )

    );

    $config = array(
        "provider" => $provider,
        "endpoint" => $endpoint,
        "signatureVersion" => OssClient::OSS_SIGNATURE_VERSION_V4,
        "region"=> "cn-hangzhou"
    );
    $ossClient = new OssClient($config);
    $ossClient->getObject($bucket, $object, $options);
} catch(OssException $e) {
    printf(__FUNCTION__ . ": FAILED\n");
    printf($e->getMessage() . "\n");
    return;
}