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AWS Mobile SDK
Xamarin Developer Guide

Using the Service Level S3 APIs

In addition to using the S3 TransferUtility, you can also interact with S3 using the low-level S3 APIs.

Initialize the Amazon S3 Client#

To use Amazon S3, we first need to create an AmazonS3Client instance which takes a reference to the CognitoAWSCredentials instance you created previously and your region:

AmazonS3Client S3Client = new AmazonS3Client (credentials,region);

Download a File#

To download a file from S3:

// Create a GetObject request
GetObjectRequest request = new GetObjectRequest
{
    BucketName = "SampleBucket",
    Key = "Item1"
};

// Issue request and remember to dispose of the response
using (GetObjectResponse response = client.GetObject(request))
{
    using (StreamReader reader = new StreamReader(response.ResponseStream))
    {
        string contents = reader.ReadToEnd();
        Console.WriteLine("Object - " + response.Key);
        Console.WriteLine(" Version Id - " + response.VersionId);
        Console.WriteLine(" Contents - " + contents);
    }
}

Upload a File#

To upload a file to S3:

// Create a client
AmazonS3Client client = new AmazonS3Client();

// Create a PutObject request
PutObjectRequest request = new PutObjectRequest
{
    BucketName = "SampleBucket",
    Key = "Item1",
    FilePath = "contents.txt"
};

// Put object
PutObjectResponse response = client.PutObject(request);

Delete an Item#

To delete an item in S3:

// Create a client
AmazonS3Client client = new AmazonS3Client();

// Create a DeleteObject request
DeleteObjectRequest request = new DeleteObjectRequest
{
    BucketName = "SampleBucket",
    Key = "Item1"
};

// Issue request
client.DeleteObject(request);

Delete Multiple Items#

To delete multiple objects from a bucket using a single HTTP request:

// Create a client
AmazonS3Client client = new AmazonS3Client();

// Create a DeleteObject request
DeleteObjectsRequest request = new DeleteObjectsRequest
{
    BucketName = "SampleBucket",
    Objects = new List<KeyVersion>
    {
        new KeyVersion() {Key = "Item1"},
        // Versioned item
        new KeyVersion() { Key = "Item2", VersionId = "Rej8CiBxcZKVK81cLr39j27Y5FVXghDK", },
        // Item in subdirectory
        new KeyVersion() { Key = "Logs/error.txt"}
    }
};

try
{
    // Issue request
    DeleteObjectsResponse response = client.DeleteObjects(request);
}
catch (DeleteObjectsException doe)
{
    // Catch error and list error details
    DeleteObjectsResponse errorResponse = doe.Response;

    foreach (DeletedObject deletedObject in errorResponse.DeletedObjects)
    {
        Console.WriteLine("Deleted item " + deletedObject.Key);
    }
    foreach (DeleteError deleteError in errorResponse.DeleteErrors)
    {
        Console.WriteLine("Error deleting item " + deleteError.Key);
        Console.WriteLine(" Code - " + deleteError.Code);
        Console.WriteLine(" Message - " + deleteError.Message);
    }
}

You may specify up to 1000 keys.

List Buckets#

To return a list of all buckets owned by the authenticated sender of the request:

// Create a client
AmazonS3Client client = new AmazonS3Client();

// Issue call
ListBucketsResponse response = client.ListBuckets();

// View response data
Console.WriteLine("Buckets owner - {0}", response.Owner.DisplayName);
foreach (S3Bucket bucket in response.Buckets)
{
    Console.WriteLine("Bucket {0}, Created on {1}", bucket.BucketName, bucket.CreationDate);
}

List Objects#

You can returns some or all (up to 1000) of the objects stored in your S3 bucket. To do so, you must have read access to the bucket.

// Create a GetObject request
GetObjectRequest request = new GetObjectRequest
{
  BucketName = "SampleBucket",
  Key = "Item1"
};

// Issue request and remember to dispose of the response
using (GetObjectResponse response = client.GetObject(request))
{
  using (StreamReader reader = new StreamReader(response.ResponseStream))
  {
      string contents = reader.ReadToEnd();
      Console.WriteLine("Object - " + response.Key);
      Console.WriteLine(" Version Id - " + response.VersionId);
      Console.WriteLine(" Contents - " + contents);
  }
}

Get a Bucket's Region#

To obtain the region that a bucket resides in:

// Create a client
AmazonS3Client client = new AmazonS3Client();

// Construct request
GetBucketLocationRequest request = new GetBucketLocationRequest
{
    BucketName = "SampleBucket"
};

// Issue call
GetBucketLocationResponse response = client.GetBucketLocation(request);

// View response data
Console.WriteLine("Bucket location - {0}", response.Location);

Get a Bucket's Policy#

To get a bucket's policy:

// Create a client
AmazonS3Client client = new AmazonS3Client();

// Construct request
GetBucketPolicyRequest getRequest = new GetBucketPolicyRequest
{
   BucketName = "SampleBucket"
};
string policy = client.GetBucketPolicy(getRequest).Policy;

Console.WriteLine(policy);
Debug.Assert(policy.Contains("BasicPerms"));