Amazon S3 examples using SDK for .NET (v4)

The following code examples show you how to perform actions and implement common scenarios by using the AWS SDK for .NET (v4) with Amazon S3.

Basics are code examples that show you how to perform the essential operations within a service.

Actions are code excerpts from larger programs and must be run in context. While actions show you how to call individual service functions, you can see actions in context in their related scenarios.

Scenarios are code examples that show you how to accomplish specific tasks by calling multiple functions within a service or combined with other AWS services.

Each example includes a link to the complete source code, where you can find instructions on how to set up and run the code in context.

Get started

The following code example shows how to get started using Amazon S3.

SDK for .NET (v4)

Note

There's more on GitHub. Find the complete example and learn how to set up and run in the AWS Code Examples Repository.


/// <summary>
/// Hello Amazon Simple Storage Service
// (Amazon S3) example.
/// </summary>
public class HelloS3
{
    /// <summary>
    /// Main method to run the Hello S3 example.
    /// </summary>
    /// <param name="args">Command line arguments.</param>
    /// <returns>A Task object.</returns>
    public static async Task Main(string[] args)
    {
        var s3Client = new AmazonS3Client();

        try
        {
            Console.WriteLine("Hello Amazon S3! Let's list your buckets:");
            Console.WriteLine(new string('-', 80));

            // Use the built-in paginator to list buckets
            var request = new ListBucketsRequest();
            var paginator = s3Client.Paginators.ListBuckets(request);

            var buckets = new List<S3Bucket>();

            await foreach (var response in paginator.Responses)
            {
                buckets.AddRange(response.Buckets);
            }

            if (buckets.Any())
            {
                Console.WriteLine($"Found {buckets.Count} S3 buckets:");
                Console.WriteLine();

                foreach (var bucket in buckets)
                {
                    Console.WriteLine($"- Bucket Name: {bucket.BucketName}");
                    Console.WriteLine($"  Creation Date: {bucket.CreationDate:yyyy-MM-dd HH:mm:ss UTC}");
                    Console.WriteLine();
                }
            }
            else
            {
                Console.WriteLine("No S3 buckets found in your account.");
            }

            Console.WriteLine("Hello S3 completed successfully.");
        }
        catch (AmazonS3Exception ex)
        {
            Console.WriteLine($"S3 service error occurred: {ex.Message}");
        }
        catch (Exception ex)
        {
            Console.WriteLine($"Couldn't list S3 buckets. Here's why: {ex.Message}");
        }
    }
}

For API details, see ListBuckets in AWS SDK for .NET API Reference.

Basics

The following code example shows how to:

Create a bucket and upload a file to it.
Download an object from a bucket.
Copy an object to a subfolder in a bucket.
List the objects in a bucket.
Delete the bucket objects and the bucket.

SDK for .NET (v4)

Note

There's more on GitHub. Find the complete example and learn how to set up and run in the AWS Code Examples Repository.

Run an interactive scenario demonstrating Amazon S3 features.


public class S3_Basics
{
    public static bool IsInteractive = true;
    public static string BucketName = null!;
    public static string TempFilePath = null!;
    public static S3Wrapper _s3Wrapper = null!;
    public static ILogger<S3_Basics> _logger = null!;

    public static async Task Main(string[] args)
    {
        // Set up dependency injection for the Amazon service.
        using var host = Host.CreateDefaultBuilder(args)
            .ConfigureServices((_, services) =>
                services.AddAWSService<IAmazonS3>()
                    .AddTransient<S3Wrapper>()
                    .AddLogging(builder => builder.AddConsole()))
            .Build();

        _logger = LoggerFactory.Create(builder => builder.AddConsole())
            .CreateLogger<S3_Basics>();

        _s3Wrapper = host.Services.GetRequiredService<S3Wrapper>();

        var sepBar = new string('-', 45);

        Console.WriteLine(sepBar);
        Console.WriteLine("Amazon Simple Storage Service (Amazon S3) basic");
        Console.WriteLine("procedures. This application will:");
        Console.WriteLine("\n\t1. Create a bucket");
        Console.WriteLine("\n\t2. Upload an object to the new bucket");
        Console.WriteLine("\n\t3. Copy the uploaded object to a folder in the bucket");
        Console.WriteLine("\n\t4. List the items in the new bucket");
        Console.WriteLine("\n\t5. Delete all the items in the bucket");
        Console.WriteLine("\n\t6. Delete the bucket");
        Console.WriteLine(sepBar);

        await RunScenario(_s3Wrapper, _logger);

        Console.WriteLine(sepBar);
        Console.WriteLine("The Amazon S3 scenario has successfully completed.");
        Console.WriteLine(sepBar);
    }

    /// <summary>
    /// Run the S3 Basics scenario with injected dependencies.
    /// </summary>
    /// <param name="s3Wrapper">The S3 wrapper instance.</param>
    /// <param name="scenarioLogger">The logger instance.</param>
    /// <returns>A Task object.</returns>
    public static async Task RunScenario(S3Wrapper s3Wrapper, ILogger<S3_Basics> scenarioLogger)
    {
        string bucketName = BucketName;
        string filePath = TempFilePath;
        string keyName = string.Empty;

        var sepBar = new string('-', 45);

        try
        {
            // Create a bucket.
            Console.WriteLine($"\n{sepBar}");
            Console.WriteLine("\nCreate a new Amazon S3 bucket.\n");
            Console.WriteLine(sepBar);

            if (IsInteractive)
            {
                Console.Write("Please enter a name for the new bucket: ");
                bucketName = Console.ReadLine();
            }
            else
            {
                Console.WriteLine($"Using bucket name: {bucketName}");
            }

            var success = await s3Wrapper.CreateBucketAsync(bucketName);
            if (success)
            {
                Console.WriteLine($"Successfully created bucket: {bucketName}.\n");
            }
            else
            {
                Console.WriteLine($"Could not create bucket: {bucketName}.\n");
            }

            Console.WriteLine(sepBar);
            Console.WriteLine("Upload a file to the new bucket.");
            Console.WriteLine(sepBar);

            if (IsInteractive)
            {
                // Get the local path and filename for the file to upload.
                while (string.IsNullOrEmpty(filePath))
                {
                    Console.Write("Please enter the path and filename of the file to upload: ");
                    filePath = Console.ReadLine();

                    // Confirm that the file exists on the local computer.
                    if (!File.Exists(filePath))
                    {
                        Console.WriteLine($"Couldn't find {filePath}. Try again.\n");
                        filePath = string.Empty;
                    }
                }
            }
            else
            {
                // Use the public variable if set, otherwise create a temp file
                if (!string.IsNullOrEmpty(TempFilePath))
                {
                    filePath = TempFilePath;
                    Console.WriteLine($"Using provided test file: {filePath}");
                }
                else
                {
                    // Create a temporary test file for non-interactive mode
                    filePath = Path.GetTempFileName();
                    var testContent = "This is a test file for S3 basics scenario.\nGenerated on: " + DateTime.UtcNow.ToString("yyyy-MM-dd HH:mm:ss UTC");
                    await File.WriteAllTextAsync(filePath, testContent);
                    Console.WriteLine($"Created temporary test file: {filePath}");
                }
            }

            // Get the file name from the full path.
            keyName = Path.GetFileName(filePath);

            success = await s3Wrapper.UploadFileAsync(bucketName, keyName, filePath);

            if (success)
            {
                Console.WriteLine($"Successfully uploaded {keyName} from {filePath} to {bucketName}.\n");
            }
            else
            {
                Console.WriteLine($"Could not upload {keyName}.\n");
            }

            // Set up download path
            string downloadPath = string.Empty;

            if (IsInteractive)
            {
                // Now get a new location where we can save the file.
                while (string.IsNullOrEmpty(downloadPath))
                {
                    // First get the path to which the file will be downloaded.
                    Console.Write("Please enter the path where the file will be downloaded: ");
                    downloadPath = Console.ReadLine();

                    // Confirm that the file doesn't already exist on the local computer.
                    if (File.Exists($"{downloadPath}\\{keyName}"))
                    {
                        Console.WriteLine($"Sorry, the file already exists in that location.\n");
                        downloadPath = string.Empty;
                    }
                }
            }
            else
            {
                downloadPath = Path.GetTempPath();
                var downloadFile = Path.Combine(downloadPath, keyName);
                if (File.Exists(downloadFile))
                {
                    File.Delete(downloadFile);
                }

                Console.WriteLine($"Using download path: {downloadPath}");
            }

            // Download an object from a bucket.
            success = await s3Wrapper.DownloadObjectFromBucketAsync(bucketName, keyName, downloadPath);

            if (success)
            {
                Console.WriteLine($"Successfully downloaded {keyName}.\n");
            }
            else
            {
                Console.WriteLine($"Sorry, could not download {keyName}.\n");
            }

            // Copy the object to a different folder in the bucket.
            string folderName = string.Empty;

            if (IsInteractive)
            {
                while (string.IsNullOrEmpty(folderName))
                {
                    Console.Write("Please enter the name of the folder to copy your object to: ");
                    folderName = Console.ReadLine();
                }
            }
            else
            {
                folderName = "test-folder";
                Console.WriteLine($"Using folder name: {folderName}");
            }

            await s3Wrapper.CopyObjectInBucketAsync(bucketName, keyName, folderName);

            // List the objects in the bucket.
            await s3Wrapper.ListBucketContentsAsync(bucketName);

            // Delete the contents of the bucket.
            if (IsInteractive)
            {
                Console.WriteLine("Press <Enter> when you are ready to delete the bucket contents.");
                _ = Console.ReadLine();
            }

            var deleteContentsSuccess = await s3Wrapper.DeleteBucketContentsAsync(bucketName);
            if (deleteContentsSuccess)
            {
                Console.WriteLine($"Successfully deleted contents of {bucketName}.\n");
            }
            else
            {
                Console.WriteLine($"Sorry, could not delete contents of {bucketName}.\n");
            }

            if (IsInteractive)
            {
                // Deleting the bucket too quickly after separately deleting its contents can
                // cause an error that the bucket isn't empty. To delete contents and bucket in one
                // operation, use AmazonS3Util.DeleteS3BucketWithObjectsAsync
                Console.WriteLine("Press <Enter> when you are ready to delete the bucket.");
                _ = Console.ReadLine();
            }
            else
            {
                // Add a small delay for non-interactive mode to ensure objects are fully deleted.
                Console.WriteLine("Waiting a moment for objects to be fully deleted...");
                await Task.Delay(2000);
            }

            // Delete the bucket.
            var deleteSuccess = await s3Wrapper.DeleteBucketAsync(bucketName);
            if (deleteSuccess)
            {
                Console.WriteLine($"Successfully deleted {bucketName}.\n");
            }
            else
            {
                Console.WriteLine($"Sorry, could not delete {bucketName}.\n");
            }

            // Clean up temporary files in non-interactive mode
            if (!IsInteractive)
            {
                try
                {
                    if (File.Exists(filePath))
                    {
                        File.Delete(filePath);
                        Console.WriteLine("Cleaned up temporary test file.");
                    }

                    var downloadFile = Path.Combine(downloadPath, keyName);
                    if (File.Exists(downloadFile))
                    {
                        File.Delete(downloadFile);
                        Console.WriteLine("Cleaned up downloaded test file.");
                    }
                }
                catch (Exception ex)
                {
                    scenarioLogger.LogWarning(ex, "Failed to clean up temporary files.");
                }
            }
        }
        catch (Exception ex)
        {
            scenarioLogger.LogError(ex, "An error occurred during the S3 scenario execution.");

            // Clean up on error - delete bucket if it exists
            try
            {
                if (!string.IsNullOrEmpty(bucketName))
                {
                    await s3Wrapper.DeleteBucketContentsAsync(bucketName);
                    await s3Wrapper.DeleteBucketAsync(bucketName);
                }
            }
            catch (Exception cleanupEx)
            {
                scenarioLogger.LogError(cleanupEx, "Error during cleanup.");
            }

            // Clean up temporary files in non-interactive mode
            if (!IsInteractive)
            {
                try
                {
                    if (!string.IsNullOrEmpty(filePath) && File.Exists(filePath))
                    {
                        File.Delete(filePath);
                    }
                }
                catch (Exception fileCleanupEx)
                {
                    scenarioLogger.LogWarning(fileCleanupEx, "Failed to clean up temporary files during error handling.");
                }
            }

            throw;
        }
    }
}

A wrapper class for Amazon S3 SDK methods.


using Amazon.S3;
using Amazon.S3.Model;

namespace S3_Actions;

/// <summary>
/// This class contains all of the methods for working with Amazon Simple
/// Storage Service (Amazon S3) buckets.
/// </summary>
public class S3Wrapper
{
    private readonly IAmazonS3 _amazonS3;

    /// <summary>
    /// Initializes a new instance of the <see cref="S3Wrapper"/> class.
    /// </summary>
    /// <param name="amazonS3">An initialized Amazon S3 client object.</param>
    public S3Wrapper(IAmazonS3 amazonS3)
    {
        _amazonS3 = amazonS3;
    }


    /// <summary>
    /// Shows how to create a new Amazon S3 bucket.
    /// </summary>
    /// <param name="bucketName">The name of the bucket to create.</param>
    /// <returns>A boolean value representing the success or failure of
    /// the bucket creation process.</returns>
    public async Task<bool> CreateBucketAsync(string bucketName)
    {
        try
        {
            var request = new PutBucketRequest
            {
                BucketName = bucketName,
                UseClientRegion = true,
            };

            var response = await _amazonS3.PutBucketAsync(request);
            return response.HttpStatusCode == System.Net.HttpStatusCode.OK;
        }
        catch (AmazonS3Exception ex)
        {
            Console.WriteLine($"Error creating bucket: '{ex.Message}'");
            return false;
        }
    }



    /// <summary>
    /// Shows how to upload a file from the local computer to an Amazon S3
    /// bucket.
    /// </summary>
    /// <param name="bucketName">The Amazon S3 bucket to which the object
    /// will be uploaded.</param>
    /// <param name="objectName">The object to upload.</param>
    /// <param name="filePath">The path, including file name, of the object
    /// on the local computer to upload.</param>
    /// <returns>A boolean value indicating the success or failure of the
    /// upload procedure.</returns>
    public async Task<bool> UploadFileAsync(
        string bucketName,
        string objectName,
        string filePath)
    {
        try
        {
            var request = new PutObjectRequest
            {
                BucketName = bucketName,
                Key = objectName,
                FilePath = filePath,
            };

            var response = await _amazonS3.PutObjectAsync(request);
            return response.HttpStatusCode == System.Net.HttpStatusCode.OK;
        }
        catch (AmazonS3Exception ex)
        {
            Console.WriteLine($"Error uploading {objectName}: {ex.Message}");
            return false;
        }
    }



    /// <summary>
    /// Shows how to download an object from an Amazon S3 bucket to the
    /// local computer.
    /// </summary>
    /// <param name="bucketName">The name of the bucket where the object is
    /// currently stored.</param>
    /// <param name="objectName">The name of the object to download.</param>
    /// <param name="filePath">The path, including filename, where the
    /// downloaded object will be stored.</param>
    /// <returns>A boolean value indicating the success or failure of the
    /// download process.</returns>
    public async Task<bool> DownloadObjectFromBucketAsync(
        string bucketName,
        string objectName,
        string filePath)
    {
        var request = new GetObjectRequest
        {
            BucketName = bucketName,
            Key = objectName,
        };

        using GetObjectResponse response = await _amazonS3.GetObjectAsync(request);

        try
        {
            // Save object to local file
            await response.WriteResponseStreamToFileAsync($"{filePath}\\{objectName}", true, CancellationToken.None);
            return response.HttpStatusCode == System.Net.HttpStatusCode.OK;
        }
        catch (AmazonS3Exception ex)
        {
            Console.WriteLine($"Error saving {objectName}: {ex.Message}");
            return false;
        }
    }



    /// <summary>
    /// Copies an object in an Amazon S3 bucket to a folder within the
    /// same bucket.
    /// </summary>
    /// <param name="bucketName">The name of the Amazon S3 bucket where the
    /// object to copy is located.</param>
    /// <param name="objectName">The object to be copied.</param>
    /// <param name="folderName">The folder to which the object will
    /// be copied.</param>
    /// <returns>A boolean value that indicates the success or failure of
    /// the copy operation.</returns>
    public async Task<bool> CopyObjectInBucketAsync(
        string bucketName,
        string objectName,
        string folderName)
    {
        try
        {
            var request = new CopyObjectRequest
            {
                SourceBucket = bucketName,
                SourceKey = objectName,
                DestinationBucket = bucketName,
                DestinationKey = $"{folderName}\\{objectName}",
            };
            var response = await _amazonS3.CopyObjectAsync(request);
            return response.HttpStatusCode == System.Net.HttpStatusCode.OK;
        }
        catch (AmazonS3Exception ex)
        {
            Console.WriteLine($"Error copying object: '{ex.Message}'");
            return false;
        }
    }



    /// <summary>
    /// Shows how to list the objects in an Amazon S3 bucket.
    /// </summary>
    /// <param name="bucketName">The name of the bucket for which to list.
    /// <param name="printList">True to print out the list.
    /// <returns>The collection of objects.</returns>
    public async Task<List<S3Object>?> ListBucketContentsAsync(string bucketName, bool printList = true)
    {
        try
        {
            var request = new ListObjectsV2Request
            {
                BucketName = bucketName,
                MaxKeys = 5,
            };

            if (printList)
            {
                Console.WriteLine("--------------------------------------");
                Console.WriteLine($"Listing the contents of {bucketName}:");
                Console.WriteLine("--------------------------------------");
            }

            var listObjectsV2Paginator = _amazonS3.Paginators.ListObjectsV2(new ListObjectsV2Request
            {
                BucketName = bucketName,
            });
            var s3Objects = new List<S3Object>();
            await foreach (var response in listObjectsV2Paginator.Responses)
            {
                if (response.S3Objects != null)
                {
                    s3Objects.AddRange(response.S3Objects);
                }
            }

            if (printList)
            {
                Console.WriteLine($"Number of Objects: {s3Objects.Count}");
                foreach (var entry in s3Objects)
                {
                    Console.WriteLine($"Key = {entry.Key} Size = {entry.Size}");
                }
            }

            return s3Objects;
        }
        catch (AmazonS3Exception ex)
        {
            Console.WriteLine($"Error encountered on server. Message:'{ex.Message}' getting list of objects.");
            return null;
        }
    }



    /// <summary>
    /// Delete all of the objects stored in an existing Amazon S3 bucket.
    /// </summary>
    /// <param name="bucketName">The name of the bucket from which the
    /// contents will be deleted.</param>
    /// <returns>A boolean value that represents the success or failure of
    /// deleting all of the objects in the bucket.</returns>
    public async Task<bool> DeleteBucketContentsAsync(string bucketName)
    {
        // Iterate over the contents of the bucket and delete all objects.
        try
        {
            // Delete all objects in the bucket.
            var deleteList = await ListBucketContentsAsync(bucketName, false);
            if (deleteList != null && deleteList.Any())
            {
                await _amazonS3.DeleteObjectsAsync(new DeleteObjectsRequest()
                {
                    BucketName = bucketName,
                    Objects = deleteList.Select(o => new KeyVersion { Key = o.Key }).ToList(),
                });
            }

            return true;
        }
        catch (AmazonS3Exception ex)
        {
            Console.WriteLine($"Error deleting objects: {ex.Message}");
            return false;
        }
    }



    /// <summary>
    /// Shows how to delete an Amazon S3 bucket.
    /// </summary>
    /// <param name="bucketName">The name of the Amazon S3 bucket to delete.</param>
    /// <returns>A boolean value that represents the success or failure of
    /// the delete operation.</returns>
    public async Task<bool> DeleteBucketAsync(string bucketName)
    {
        try
        {
            var request = new DeleteBucketRequest { BucketName = bucketName, };

            await _amazonS3.DeleteBucketAsync(request);
            return true;
        }
        catch (AmazonS3Exception ex)
        {
            Console.WriteLine($"Error deleting bucket: {ex.Message}");
            return false;
        }
    }

}

For API details, see the following topics in AWS SDK for .NET API Reference.

Actions

The following code example shows how to use CopyObject.

SDK for .NET (v4)

Note

There's more on GitHub. Find the complete example and learn how to set up and run in the AWS Code Examples Repository.



    /// <summary>
    /// Copies an object in an Amazon S3 bucket to a folder within the
    /// same bucket.
    /// </summary>
    /// <param name="bucketName">The name of the Amazon S3 bucket where the
    /// object to copy is located.</param>
    /// <param name="objectName">The object to be copied.</param>
    /// <param name="folderName">The folder to which the object will
    /// be copied.</param>
    /// <returns>A boolean value that indicates the success or failure of
    /// the copy operation.</returns>
    public async Task<bool> CopyObjectInBucketAsync(
        string bucketName,
        string objectName,
        string folderName)
    {
        try
        {
            var request = new CopyObjectRequest
            {
                SourceBucket = bucketName,
                SourceKey = objectName,
                DestinationBucket = bucketName,
                DestinationKey = $"{folderName}\\{objectName}",
            };
            var response = await _amazonS3.CopyObjectAsync(request);
            return response.HttpStatusCode == System.Net.HttpStatusCode.OK;
        }
        catch (AmazonS3Exception ex)
        {
            Console.WriteLine($"Error copying object: '{ex.Message}'");
            return false;
        }
    }

For API details, see CopyObject in AWS SDK for .NET API Reference.

The following code example shows how to use CreateBucket.

SDK for .NET (v4)

Note

There's more on GitHub. Find the complete example and learn how to set up and run in the AWS Code Examples Repository.



    /// <summary>
    /// Shows how to create a new Amazon S3 bucket.
    /// </summary>
    /// <param name="bucketName">The name of the bucket to create.</param>
    /// <returns>A boolean value representing the success or failure of
    /// the bucket creation process.</returns>
    public async Task<bool> CreateBucketAsync(string bucketName)
    {
        try
        {
            var request = new PutBucketRequest
            {
                BucketName = bucketName,
                UseClientRegion = true,
            };

            var response = await _amazonS3.PutBucketAsync(request);
            return response.HttpStatusCode == System.Net.HttpStatusCode.OK;
        }
        catch (AmazonS3Exception ex)
        {
            Console.WriteLine($"Error creating bucket: '{ex.Message}'");
            return false;
        }
    }

For API details, see CreateBucket in AWS SDK for .NET API Reference.

The following code example shows how to use CreatePresignedPost.

SDK for .NET (v4)

Note

There's more on GitHub. Find the complete example and learn how to set up and run in the AWS Code Examples Repository.

Create a presigned POST URL.


    /// <summary>
    /// Create a presigned POST URL with conditions.
    /// </summary>
    /// <param name="s3Client">The Amazon S3 client.</param>
    /// <param name="bucketName">The name of the bucket.</param>
    /// <param name="objectKey">The object key (path) where the uploaded file will be stored.</param>
    /// <param name="expires">When the presigned URL expires.</param>
    /// <param name="fields">Dictionary of fields to add to the form.</param>
    /// <param name="conditions">List of conditions to apply.</param>
    /// <returns>A CreatePresignedPostResponse object with URL and form fields.</returns>
    public async Task<CreatePresignedPostResponse> CreatePresignedPostAsync(
        IAmazonS3 s3Client,
        string bucketName,
        string objectKey,
        DateTime expires,
        Dictionary<string, string>? fields = null,
        List<S3PostCondition>? conditions = null)
    {
        var request = new CreatePresignedPostRequest
        {
            BucketName = bucketName,
            Key = objectKey,
            Expires = expires
        };

        // Add custom fields if provided
        if (fields != null)
        {
            foreach (var field in fields)
            {
                request.Fields.Add(field.Key, field.Value);
            }
        }

        // Add conditions if provided
        if (conditions != null)
        {
            foreach (var condition in conditions)
            {
                request.Conditions.Add(condition);
            }
        }

        return await s3Client.CreatePresignedPostAsync(request);
    }

For API details, see CreatePresignedPost in AWS SDK for .NET API Reference.

The following code example shows how to use DeleteBucket.

SDK for .NET (v4)

Note

There's more on GitHub. Find the complete example and learn how to set up and run in the AWS Code Examples Repository.



    /// <summary>
    /// Shows how to delete an Amazon S3 bucket.
    /// </summary>
    /// <param name="bucketName">The name of the Amazon S3 bucket to delete.</param>
    /// <returns>A boolean value that represents the success or failure of
    /// the delete operation.</returns>
    public async Task<bool> DeleteBucketAsync(string bucketName)
    {
        try
        {
            var request = new DeleteBucketRequest { BucketName = bucketName, };

            await _amazonS3.DeleteBucketAsync(request);
            return true;
        }
        catch (AmazonS3Exception ex)
        {
            Console.WriteLine($"Error deleting bucket: {ex.Message}");
            return false;
        }
    }

For API details, see DeleteBucket in AWS SDK for .NET API Reference.

The following code example shows how to use DeleteObjects.

SDK for .NET (v4)

Note

There's more on GitHub. Find the complete example and learn how to set up and run in the AWS Code Examples Repository.



    /// <summary>
    /// Delete all of the objects stored in an existing Amazon S3 bucket.
    /// </summary>
    /// <param name="bucketName">The name of the bucket from which the
    /// contents will be deleted.</param>
    /// <returns>A boolean value that represents the success or failure of
    /// deleting all of the objects in the bucket.</returns>
    public async Task<bool> DeleteBucketContentsAsync(string bucketName)
    {
        // Iterate over the contents of the bucket and delete all objects.
        try
        {
            // Delete all objects in the bucket.
            var deleteList = await ListBucketContentsAsync(bucketName, false);
            if (deleteList != null && deleteList.Any())
            {
                await _amazonS3.DeleteObjectsAsync(new DeleteObjectsRequest()
                {
                    BucketName = bucketName,
                    Objects = deleteList.Select(o => new KeyVersion { Key = o.Key }).ToList(),
                });
            }

            return true;
        }
        catch (AmazonS3Exception ex)
        {
            Console.WriteLine($"Error deleting objects: {ex.Message}");
            return false;
        }
    }

For API details, see DeleteObjects in AWS SDK for .NET API Reference.

The following code example shows how to use GetObject.

SDK for .NET (v4)

Note

There's more on GitHub. Find the complete example and learn how to set up and run in the AWS Code Examples Repository.



    /// <summary>
    /// Shows how to download an object from an Amazon S3 bucket to the
    /// local computer.
    /// </summary>
    /// <param name="bucketName">The name of the bucket where the object is
    /// currently stored.</param>
    /// <param name="objectName">The name of the object to download.</param>
    /// <param name="filePath">The path, including filename, where the
    /// downloaded object will be stored.</param>
    /// <returns>A boolean value indicating the success or failure of the
    /// download process.</returns>
    public async Task<bool> DownloadObjectFromBucketAsync(
        string bucketName,
        string objectName,
        string filePath)
    {
        var request = new GetObjectRequest
        {
            BucketName = bucketName,
            Key = objectName,
        };

        using GetObjectResponse response = await _amazonS3.GetObjectAsync(request);

        try
        {
            // Save object to local file
            await response.WriteResponseStreamToFileAsync($"{filePath}\\{objectName}", true, CancellationToken.None);
            return response.HttpStatusCode == System.Net.HttpStatusCode.OK;
        }
        catch (AmazonS3Exception ex)
        {
            Console.WriteLine($"Error saving {objectName}: {ex.Message}");
            return false;
        }
    }

For API details, see GetObject in AWS SDK for .NET API Reference.

The following code example shows how to use ListObjectsV2.

SDK for .NET (v4)

Note

There's more on GitHub. Find the complete example and learn how to set up and run in the AWS Code Examples Repository.



    /// <summary>
    /// Shows how to list the objects in an Amazon S3 bucket.
    /// </summary>
    /// <param name="bucketName">The name of the bucket for which to list.
    /// <param name="printList">True to print out the list.
    /// <returns>The collection of objects.</returns>
    public async Task<List<S3Object>?> ListBucketContentsAsync(string bucketName, bool printList = true)
    {
        try
        {
            var request = new ListObjectsV2Request
            {
                BucketName = bucketName,
                MaxKeys = 5,
            };

            if (printList)
            {
                Console.WriteLine("--------------------------------------");
                Console.WriteLine($"Listing the contents of {bucketName}:");
                Console.WriteLine("--------------------------------------");
            }

            var listObjectsV2Paginator = _amazonS3.Paginators.ListObjectsV2(new ListObjectsV2Request
            {
                BucketName = bucketName,
            });
            var s3Objects = new List<S3Object>();
            await foreach (var response in listObjectsV2Paginator.Responses)
            {
                if (response.S3Objects != null)
                {
                    s3Objects.AddRange(response.S3Objects);
                }
            }

            if (printList)
            {
                Console.WriteLine($"Number of Objects: {s3Objects.Count}");
                foreach (var entry in s3Objects)
                {
                    Console.WriteLine($"Key = {entry.Key} Size = {entry.Size}");
                }
            }

            return s3Objects;
        }
        catch (AmazonS3Exception ex)
        {
            Console.WriteLine($"Error encountered on server. Message:'{ex.Message}' getting list of objects.");
            return null;
        }
    }

For API details, see ListObjectsV2 in AWS SDK for .NET API Reference.

The following code example shows how to use PutObject.

SDK for .NET (v4)

Note

There's more on GitHub. Find the complete example and learn how to set up and run in the AWS Code Examples Repository.



    /// <summary>
    /// Shows how to upload a file from the local computer to an Amazon S3
    /// bucket.
    /// </summary>
    /// <param name="bucketName">The Amazon S3 bucket to which the object
    /// will be uploaded.</param>
    /// <param name="objectName">The object to upload.</param>
    /// <param name="filePath">The path, including file name, of the object
    /// on the local computer to upload.</param>
    /// <returns>A boolean value indicating the success or failure of the
    /// upload procedure.</returns>
    public async Task<bool> UploadFileAsync(
        string bucketName,
        string objectName,
        string filePath)
    {
        try
        {
            var request = new PutObjectRequest
            {
                BucketName = bucketName,
                Key = objectName,
                FilePath = filePath,
            };

            var response = await _amazonS3.PutObjectAsync(request);
            return response.HttpStatusCode == System.Net.HttpStatusCode.OK;
        }
        catch (AmazonS3Exception ex)
        {
            Console.WriteLine($"Error uploading {objectName}: {ex.Message}");
            return false;
        }
    }

For API details, see PutObject in AWS SDK for .NET API Reference.

Scenarios

The following code example shows how to create a presigned URL for Amazon S3 and upload an object.

SDK for .NET (v4)

Note

There's more on GitHub. Find the complete example and learn how to set up and run in the AWS Code Examples Repository.

Create and use presigned POST URLs for direct browser uploads.


/// <summary>
/// Scenario demonstrating the complete workflow for presigned POST URLs:
/// 1. Create an S3 bucket
/// 2. Create a presigned POST URL
/// 3. Upload a file using the presigned POST URL
/// 4. Clean up resources
/// </summary>
public class CreatePresignedPostBasics
{
    public static ILogger<CreatePresignedPostBasics> _logger = null!;
    public static S3Wrapper _s3Wrapper = null!;
    public static UiMethods _uiMethods = null!;
    public static IHttpClientFactory _httpClientFactory = null!;
    public static bool _isInteractive = true;
    public static string? _bucketName;
    public static string? _objectKey;

    /// <summary>
    /// Set up the services and logging.
    /// </summary>
    /// <param name="host">The IHost instance.</param>
    public static void SetUpServices(IHost host)
    {
        var loggerFactory = LoggerFactory.Create(builder =>
        {
            builder.AddConsole();
        });
        _logger = new Logger<CreatePresignedPostBasics>(loggerFactory);

        _s3Wrapper = host.Services.GetRequiredService<S3Wrapper>();
        _httpClientFactory = host.Services.GetRequiredService<IHttpClientFactory>();
        _uiMethods = new UiMethods();
    }

    /// <summary>
    /// Perform the actions defined for the Amazon S3 Presigned POST scenario.
    /// </summary>
    /// <param name="args">Command line arguments.</param>
    /// <returns>A Task object.</returns>
    public static async Task Main(string[] args)
    {
        _isInteractive = !args.Contains("--non-interactive");

        // Set up dependency injection for Amazon S3
        using var host = Microsoft.Extensions.Hosting.Host.CreateDefaultBuilder(args)
            .ConfigureServices((_, services) =>
                services.AddAWSService<IAmazonS3>()
                    .AddTransient<S3Wrapper>()
                    .AddHttpClient()
            )
            .Build();

        SetUpServices(host);

        try
        {
            // Display overview
            _uiMethods.DisplayOverview();
            _uiMethods.PressEnter(_isInteractive);

            // Step 1: Create bucket
            await CreateBucketAsync();
            _uiMethods.PressEnter(_isInteractive);

            // Step 2: Create presigned URL
            _uiMethods.DisplayTitle("Step 2: Create presigned POST URL");
            var response = await CreatePresignedPostAsync();
            _uiMethods.PressEnter(_isInteractive);

            // Step 3: Display URL and fields
            _uiMethods.DisplayTitle("Step 3: Presigned POST URL details");
            DisplayPresignedPostFields(response);
            _uiMethods.PressEnter(_isInteractive);

            // Step 4: Upload file
            _uiMethods.DisplayTitle("Step 4: Upload test file using presigned POST URL");
            await UploadFileAsync(response);
            _uiMethods.PressEnter(_isInteractive);

            // Step 5: Verify file exists
            await VerifyFileExistsAsync();
            _uiMethods.PressEnter(_isInteractive);

            // Step 6: Cleanup
            _uiMethods.DisplayTitle("Step 6: Clean up resources");
            await CleanupAsync();

            _uiMethods.DisplayTitle("S3 Presigned POST Scenario completed successfully!");
            _uiMethods.PressEnter(_isInteractive);
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "Error in scenario");
            Console.WriteLine($"Error: {ex.Message}");

            // Attempt cleanup if there was an error
            if (!string.IsNullOrEmpty(_bucketName))
            {
                _uiMethods.DisplayTitle("Cleaning up resources after error");
                await _s3Wrapper.DeleteBucketAsync(_bucketName);
                Console.WriteLine($"Cleaned up bucket: {_bucketName}");
            }
        }
    }

    /// <summary>
    /// Create an S3 bucket for the scenario.
    /// </summary>
    private static async Task CreateBucketAsync()
    {
        _uiMethods.DisplayTitle("Step 1: Create an S3 bucket");

        // Generate a default bucket name for the scenario
        var defaultBucketName = $"presigned-post-demo-{DateTime.Now:yyyyMMddHHmmss}".ToLower();

        // Prompt user for bucket name or use default in non-interactive mode
        _bucketName = _uiMethods.GetUserInput(
            $"Enter S3 bucket name (or press Enter for '{defaultBucketName}'): ",
            defaultBucketName,
            _isInteractive);

        // Basic validation to ensure bucket name is not empty
        if (string.IsNullOrWhiteSpace(_bucketName))
        {
            _bucketName = defaultBucketName;
        }

        Console.WriteLine($"Creating bucket: {_bucketName}");

        await _s3Wrapper.CreateBucketAsync(_bucketName);

        Console.WriteLine($"Successfully created bucket: {_bucketName}");
    }


    /// <summary>
    /// Create a presigned POST URL.
    /// </summary>
    private static async Task<CreatePresignedPostResponse> CreatePresignedPostAsync()
    {
        _objectKey = "example-upload.txt";
        var expiration = DateTime.UtcNow.AddMinutes(10); // Short expiration for the demo

        Console.WriteLine($"Creating presigned POST URL for {_bucketName}/{_objectKey}");
        Console.WriteLine($"Expiration: {expiration} UTC");

        var s3Client = _s3Wrapper.GetS3Client();

        var response = await _s3Wrapper.CreatePresignedPostAsync(
            s3Client, _bucketName!, _objectKey, expiration);

        Console.WriteLine("Successfully created presigned POST URL");
        return response;
    }

    /// <summary>
    /// Upload a file using the presigned POST URL.
    /// </summary>
    private static async Task UploadFileAsync(CreatePresignedPostResponse response)
    {

        // Create a temporary test file to upload
        string testFilePath = Path.GetTempFileName();
        string testContent = "This is a test file for the S3 presigned POST scenario.";

        await File.WriteAllTextAsync(testFilePath, testContent);
        Console.WriteLine($"Created test file at: {testFilePath}");

        // Upload the file using the presigned POST URL
        Console.WriteLine("\nUploading file using the presigned POST URL...");
        var uploadResult = await UploadFileWithPresignedPostAsync(response, testFilePath);

        // Display the upload result
        if (uploadResult.Success)
        {
            Console.WriteLine($"Upload successful! Status code: {uploadResult.StatusCode}");
        }
        else
        {
            Console.WriteLine($"Upload failed with status code: {uploadResult.StatusCode}");
            Console.WriteLine($"Error: {uploadResult.Response}");
            throw new Exception("File upload failed");
        }

        // Clean up the temporary file
        File.Delete(testFilePath);
        Console.WriteLine("Temporary file deleted");
    }

    /// <summary>
    /// Helper method to upload a file using a presigned POST URL.
    /// </summary>
    private static async Task<(bool Success, HttpStatusCode StatusCode, string Response)> UploadFileWithPresignedPostAsync(
        CreatePresignedPostResponse response,
        string filePath)
    {
        try
        {
            _logger.LogInformation("Uploading file {filePath} using presigned POST URL", filePath);

            using var httpClient = _httpClientFactory.CreateClient();
            using var formContent = new MultipartFormDataContent();

            // Add all the fields from the presigned POST response
            foreach (var field in response.Fields)
            {
                formContent.Add(new StringContent(field.Value), field.Key);
            }

            // Add the file content
            var fileStream = File.OpenRead(filePath);
            var fileName = Path.GetFileName(filePath);
            var fileContent = new StreamContent(fileStream);
            fileContent.Headers.ContentType = new MediaTypeHeaderValue("text/plain");
            formContent.Add(fileContent, "file", fileName);

            // Send the POST request
            var httpResponse = await httpClient.PostAsync(response.Url, formContent);
            var responseContent = await httpResponse.Content.ReadAsStringAsync();

            // Log and return the result
            _logger.LogInformation("Upload completed with status code {statusCode}", httpResponse.StatusCode);

            return (httpResponse.IsSuccessStatusCode, httpResponse.StatusCode, responseContent);
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "Error uploading file");
            return (false, HttpStatusCode.InternalServerError, ex.Message);
        }
    }

    /// <summary>
    /// Verify that the uploaded file exists in the S3 bucket.
    /// </summary>
    private static async Task VerifyFileExistsAsync()
    {
        _uiMethods.DisplayTitle("Step 5: Verify uploaded file exists");

        Console.WriteLine($"Checking if file exists at {_bucketName}/{_objectKey}...");

        try
        {
            var metadata = await _s3Wrapper.GetObjectMetadataAsync(_bucketName!, _objectKey!);

            Console.WriteLine($"File verification successful! File exists in the bucket.");
            Console.WriteLine($"File size: {metadata.ContentLength} bytes");
            Console.WriteLine($"File type: {metadata.Headers.ContentType}");
            Console.WriteLine($"Last modified: {metadata.LastModified}");
        }
        catch (AmazonS3Exception ex) when (ex.StatusCode == System.Net.HttpStatusCode.NotFound)
        {
            Console.WriteLine($"Error: File was not found in the bucket.");
            throw;
        }
    }

    private static void DisplayPresignedPostFields(CreatePresignedPostResponse response)
    {
        Console.WriteLine($"Presigned POST URL: {response.Url}");
        Console.WriteLine("Form fields to include:");

        foreach (var field in response.Fields)
        {
            Console.WriteLine($"  {field.Key}: {field.Value}");
        }
    }

    /// <summary>
    /// Clean up resources created by the scenario.
    /// </summary>
    private static async Task CleanupAsync()
    {
        if (!string.IsNullOrEmpty(_bucketName))
        {
            Console.WriteLine($"Deleting bucket {_bucketName} and its contents...");
            bool result = await _s3Wrapper.DeleteBucketAsync(_bucketName);

            if (result)
            {
                Console.WriteLine("Bucket deleted successfully");
            }
            else
            {
                Console.WriteLine("Failed to delete bucket - it may have been already deleted");
            }
        }
    }
}

Warning Javascript is disabled or is unavailable in your browser.

To use the Amazon Web Services Documentation, Javascript must be enabled. Please refer to your browser's Help pages for instructions.

Document Conventions

Amazon Redshift

AWS CLI with Bash script