Esempi SDK per .NET di DynamoDB con (v4)

using Amazon.DynamoDBv2;
using Amazon.DynamoDBv2.Model;
using Microsoft.Extensions.DependencyInjection;

namespace DynamoDBActions;

/// <summary>
/// A simple example that demonstrates basic DynamoDB operations.
/// </summary>
public class HelloDynamoDB
{
    /// <summary>
    /// HelloDynamoDB lists the existing DynamoDB tables for the default user.
    /// </summary>
    /// <param name="args">Command line arguments</param>
    /// <returns>Async task.</returns>
    static async Task Main(string[] args)
    {
        // Set up dependency injection for Amazon DynamoDB.
        using var host = Microsoft.Extensions.Hosting.Host.CreateDefaultBuilder(args)
            .ConfigureServices((_, services) =>
                services.AddAWSService<IAmazonDynamoDB>()
            )
            .Build();

        // Now the client is available for injection.
        var dynamoDbClient = host.Services.GetRequiredService<IAmazonDynamoDB>();

        try
        {
            var request = new ListTablesRequest();
            var tableNames = new List<string>();

            var paginatorForTables = dynamoDbClient.Paginators.ListTables(request);

            await foreach (var tableName in paginatorForTables.TableNames)
            {
                tableNames.Add(tableName);
            }

            Console.WriteLine("Welcome to the DynamoDB Hello Service example. " +
                              "\nLet's list your DynamoDB tables:");
            tableNames.ForEach(table =>
            {
                Console.WriteLine($"Table: {table}");
            });
        }
        catch (AmazonDynamoDBException ex)
        {
            Console.WriteLine($"An Amazon DynamoDB service error occurred while listing tables. {ex.Message}");
        }
        catch (Exception ex)
        {
            Console.WriteLine($"An error occurred while listing tables. {ex.Message}");
        }
    }
}

/// <summary>
/// This example application performs the following basic Amazon DynamoDB
/// functions:
///     CreateTableAsync
///     PutItemAsync
///     UpdateItemAsync
///     BatchWriteItemAsync
///     GetItemAsync
///     DeleteItemAsync
///     Query
///     Scan
///     DeleteItemAsync.
/// </summary>
public class DynamoDbBasics
{
    public static bool IsInteractive = true;

    // Separator for the console display.
    private static readonly string SepBar = new string('-', 80);

    /// <summary>
    /// The main entry point for the DynamoDB Basics example application.
    /// </summary>
    /// <param name="args">Command line arguments.</param>
    /// <returns>A task representing the asynchronous operation.</returns>
    public static async Task Main(string[] args)
    {
        // Set up dependency injection for Amazon DynamoDB.
        using var host = Microsoft.Extensions.Hosting.Host.CreateDefaultBuilder(args)
            .ConfigureServices((_, services) =>
                services.AddAWSService<IAmazonDynamoDB>()
                    .AddTransient<DynamoDbWrapper>())
            .Build();

        // Now the wrapper is available for injection.
        var dynamoDbWrapper = host.Services.GetRequiredService<DynamoDbWrapper>();

        var tableName = "movie_table";

        var movieFileName = @"movies.json";

        DisplayInstructions();

        // Create a new table and wait for it to be active.
        Console.WriteLine($"Creating the new table: {tableName}");

        var success = await dynamoDbWrapper.CreateMovieTableAsync(tableName);

        Console.WriteLine(success
            ? $"\nTable: {tableName} successfully created."
            : $"\nCould not create {tableName}.");

        WaitForEnter();

        // Add a single new movie to the table.
        var newMovie = new Movie
        {
            Year = 2021,
            Title = "Spider-Man: No Way Home",
        };

        success = await dynamoDbWrapper.PutItemAsync(newMovie, tableName);
        if (success)
        {
            Console.WriteLine($"Added {newMovie.Title} to the table.");
        }
        else
        {
            Console.WriteLine("Could not add movie to table.");
        }

        WaitForEnter();

        // Update the new movie by adding a plot and rank.
        var newInfo = new MovieInfo
        {
            Plot = "With Spider-Man's identity now revealed, Peter asks" +
                   "Doctor Strange for help. When a spell goes wrong, dangerous" +
                   "foes from other worlds start to appear, forcing Peter to" +
                   "discover what it truly means to be Spider-Man.",
            Rank = 9,
        };

        success = await dynamoDbWrapper.UpdateItemAsync(newMovie, newInfo, tableName);
        if (success)
        {
            Console.WriteLine($"Successfully updated the movie: {newMovie.Title}");
        }
        else
        {
            Console.WriteLine("Could not update the movie.");
        }

        WaitForEnter();

        // Add a batch of movies to the DynamoDB table from a list of
        // movies in a JSON file.
        var itemCount = await dynamoDbWrapper.BatchWriteItemsAsync(movieFileName, tableName);
        Console.WriteLine($"Added {itemCount} movies to the table.");

        WaitForEnter();

        // Get a movie by key. (partition + sort)
        var lookupMovie = new Movie
        {
            Title = "Jurassic Park",
            Year = 1993,
        };

        Console.WriteLine("Looking for the movie \"Jurassic Park\".");
        var item = await dynamoDbWrapper.GetItemAsync(lookupMovie, tableName);
        if (item?.Count > 0)
        {
            dynamoDbWrapper.DisplayItem(item);
        }
        else
        {
            Console.WriteLine($"Couldn't find {lookupMovie.Title}");
        }

        WaitForEnter();

        // Delete a movie.
        var movieToDelete = new Movie
        {
            Title = "The Town",
            Year = 2010,
        };

        success = await dynamoDbWrapper.DeleteItemAsync(tableName, movieToDelete);

        if (success)
        {
            Console.WriteLine($"Successfully deleted {movieToDelete.Title}.");
        }
        else
        {
            Console.WriteLine($"Could not delete {movieToDelete.Title}.");
        }

        WaitForEnter();

        // Use Query to find all the movies released in 2010.
        int findYear = 2010;
        Console.WriteLine($"Movies released in {findYear}");
        var queryCount = await dynamoDbWrapper.QueryMoviesAsync(tableName, findYear);
        Console.WriteLine($"Found {queryCount} movies released in {findYear}");

        WaitForEnter();

        // Use Scan to get a list of movies from 2001 to 2011.
        int startYear = 2001;
        int endYear = 2011;
        var scanCount = await dynamoDbWrapper.ScanTableAsync(tableName, startYear, endYear);
        Console.WriteLine($"Found {scanCount} movies released between {startYear} and {endYear}");

        WaitForEnter();

        // Delete the table.
        success = await dynamoDbWrapper.DeleteTableAsync(tableName);

        if (success)
        {
            Console.WriteLine($"Successfully deleted {tableName}");
        }
        else
        {
            Console.WriteLine($"Could not delete {tableName}");
        }

        Console.WriteLine("The DynamoDB Basics example application is complete.");

        WaitForEnter();
    }

    /// <summary>
    /// Displays the description of the application on the console.
    /// </summary>
    private static void DisplayInstructions()
    {
        if (!IsInteractive)
        {
            return;
        }

        Console.Clear();
        Console.WriteLine();
        Console.Write(new string(' ', 28));
        Console.WriteLine("DynamoDB Basics Example");
        Console.WriteLine(SepBar);
        Console.WriteLine("This demo application shows the basics of using DynamoDB with the AWS SDK.");
        Console.WriteLine(SepBar);
        Console.WriteLine("The application does the following:");
        Console.WriteLine("\t1. Creates a table with partition: year and sort:title.");
        Console.WriteLine("\t2. Adds a single movie to the table.");
        Console.WriteLine("\t3. Adds movies to the table from moviedata.json.");
        Console.WriteLine("\t4. Updates the rating and plot of the movie that was just added.");
        Console.WriteLine("\t5. Gets a movie using its key (partition + sort).");
        Console.WriteLine("\t6. Deletes a movie.");
        Console.WriteLine("\t7. Uses QueryAsync to return all movies released in a given year.");
        Console.WriteLine("\t8. Uses ScanAsync to return all movies released within a range of years.");
        Console.WriteLine("\t9. Finally, it deletes the table that was just created.");
        WaitForEnter();
    }

    /// <summary>
    /// Simple method to wait for the Enter key to be pressed.
    /// </summary>
    private static void WaitForEnter()
    {
        if (IsInteractive)
        {
            Console.WriteLine("\nPress <Enter> to continue.");
            Console.WriteLine(SepBar);
            _ = Console.ReadLine();
        }
    }
}

Crea una tabella per contenere i dati del filmato.

    /// <summary>
    /// Creates a new Amazon DynamoDB table and then waits for the new
    /// table to become active.
    /// </summary>
    /// <param name="tableName">The name of the table to create.</param>
    /// <returns>A Boolean value indicating the success of the operation.</returns>
    public async Task<bool> CreateMovieTableAsync(string tableName)
    {
        try
        {
            var response = await _amazonDynamoDB.CreateTableAsync(new CreateTableRequest
            {
                TableName = tableName,
                AttributeDefinitions = new List<AttributeDefinition>()
                {
                    new AttributeDefinition
                    {
                        AttributeName = "title",
                        AttributeType = ScalarAttributeType.S,
                    },
                    new AttributeDefinition
                    {
                        AttributeName = "year",
                        AttributeType = ScalarAttributeType.N,
                    },
                },
                KeySchema = new List<KeySchemaElement>()
                {
                    new KeySchemaElement
                    {
                        AttributeName = "year",
                        KeyType = KeyType.HASH,
                    },
                    new KeySchemaElement
                    {
                        AttributeName = "title",
                        KeyType = KeyType.RANGE,
                    },
                },
                BillingMode = BillingMode.PAY_PER_REQUEST,
            });

            // Wait until the table is ACTIVE and then report success.
            Console.Write("Waiting for table to become active...");

            var request = new DescribeTableRequest
            {
                TableName = response.TableDescription.TableName,
            };

            TableStatus status;

            int sleepDuration = 2000;

            do
            {
                Thread.Sleep(sleepDuration);

                var describeTableResponse = await _amazonDynamoDB.DescribeTableAsync(request);
                status = describeTableResponse.Table.TableStatus;

                Console.Write(".");
            }
            while (status != "ACTIVE");

            return status == TableStatus.ACTIVE;
        }
        catch (ResourceInUseException ex)
        {
            Console.WriteLine($"Table {tableName} already exists. {ex.Message}");
            throw;
        }
        catch (AmazonDynamoDBException ex)
        {
            Console.WriteLine($"An Amazon DynamoDB error occurred while creating table {tableName}. {ex.Message}");
            throw;
        }
        catch (Exception ex)
        {
            Console.WriteLine($"An error occurred while creating table {tableName}. {ex.Message}");
            throw;
        }
    }

Aggiunge un singolo filmato alla tabella.

    /// <summary>
    /// Adds a new item to the table.
    /// </summary>
    /// <param name="newMovie">A Movie object containing informtation for
    /// the movie to add to the table.</param>
    /// <param name="tableName">The name of the table where the item will be added.</param>
    /// <returns>A Boolean value that indicates the results of adding the item.</returns>
    public async Task<bool> PutItemAsync(Movie newMovie, string tableName)
    {
        try
        {
            var item = new Dictionary<string, AttributeValue>
            {
                ["title"] = new AttributeValue { S = newMovie.Title },
                ["year"] = new AttributeValue { N = newMovie.Year.ToString() },
            };

            var request = new PutItemRequest
            {
                TableName = tableName,
                Item = item,
            };

            await _amazonDynamoDB.PutItemAsync(request);
            return true;
        }
        catch (ResourceNotFoundException ex)
        {
            Console.WriteLine($"Table {tableName} was not found. {ex.Message}");
            return false;
        }
        catch (AmazonDynamoDBException ex)
        {
            Console.WriteLine($"An Amazon DynamoDB error occurred while putting item. {ex.Message}");
            throw;
        }
        catch (Exception ex)
        {
            Console.WriteLine($"An error occurred while putting item. {ex.Message}");
            throw;
        }
    }

Aggiorna un singolo elemento in una tabella.

    /// <summary>
    /// Updates an existing item in the movies table.
    /// </summary>
    /// <param name="newMovie">A Movie object containing information for
    /// the movie to update.</param>
    /// <param name="newInfo">A MovieInfo object that contains the
    /// information that will be changed.</param>
    /// <param name="tableName">The name of the table that contains the movie.</param>
    /// <returns>A Boolean value that indicates the success of the operation.</returns>
    public async Task<bool> UpdateItemAsync(
        Movie newMovie,
        MovieInfo newInfo,
        string tableName)
    {
        try
        {
            var key = new Dictionary<string, AttributeValue>
            {
                ["title"] = new AttributeValue { S = newMovie.Title },
                ["year"] = new AttributeValue { N = newMovie.Year.ToString() },
            };
            var updates = new Dictionary<string, AttributeValueUpdate>
            {
                ["info.plot"] = new AttributeValueUpdate
                {
                    Action = AttributeAction.PUT,
                    Value = new AttributeValue { S = newInfo.Plot },
                },

                ["info.rating"] = new AttributeValueUpdate
                {
                    Action = AttributeAction.PUT,
                    Value = new AttributeValue { N = newInfo.Rank.ToString() },
                },
            };

            var request = new UpdateItemRequest
            {
                AttributeUpdates = updates,
                Key = key,
                TableName = tableName,
            };

            await _amazonDynamoDB.UpdateItemAsync(request);
            return true;
        }
        catch (ResourceNotFoundException ex)
        {
            Console.WriteLine($"Table {tableName} or item was not found. {ex.Message}");
            return false;
        }
        catch (AmazonDynamoDBException ex)
        {
            Console.WriteLine($"An Amazon DynamoDB error occurred while updating item. {ex.Message}");
            throw;
        }
        catch (Exception ex)
        {
            Console.WriteLine($"An error occurred while updating item. {ex.Message}");
            throw;
        }
    }

Recupera un singolo elemento dalla tabella del filmato.

    /// <summary>
    /// Gets information about an existing movie from the table.
    /// </summary>
    /// <param name="newMovie">A Movie object containing information about
    /// the movie to retrieve.</param>
    /// <param name="tableName">The name of the table containing the movie.</param>
    /// <returns>A Dictionary object containing information about the item
    /// retrieved.</returns>
    public async Task<Dictionary<string, AttributeValue>> GetItemAsync(Movie newMovie, string tableName)
    {
        try
        {
            var key = new Dictionary<string, AttributeValue>
            {
                ["title"] = new AttributeValue { S = newMovie.Title },
                ["year"] = new AttributeValue { N = newMovie.Year.ToString() },
            };

            var request = new GetItemRequest
            {
                Key = key,
                TableName = tableName,
            };

            var response = await _amazonDynamoDB.GetItemAsync(request);
            return response.Item;
        }
        catch (ResourceNotFoundException ex)
        {
            Console.WriteLine($"Table {tableName} was not found. {ex.Message}");
            return new Dictionary<string, AttributeValue>();
        }
        catch (AmazonDynamoDBException ex)
        {
            Console.WriteLine($"An Amazon DynamoDB error occurred while getting item. {ex.Message}");
            throw;
        }
        catch (Exception ex)
        {
            Console.WriteLine($"An error occurred while getting item. {ex.Message}");
            throw;
        }
    }

Scrive un batch di elementi nella tabella del filmato.

    /// <summary>
    /// Loads the contents of a JSON file into a list of movies to be
    /// added to the DynamoDB table.
    /// </summary>
    /// <param name="movieFileName">The name of the JSON file.</param>
    /// <returns>A generic list of movie objects.</returns>
    public List<Movie> ImportMovies(string movieFileName)
    {
        var moviesList = new List<Movie>();
        if (!File.Exists(movieFileName))
        {
            return moviesList;
        }

        using var sr = new StreamReader(movieFileName);
        string json = sr.ReadToEnd();
        var allMovies = JsonSerializer.Deserialize<List<Movie>>(
            json,
            new JsonSerializerOptions
            {
                PropertyNameCaseInsensitive = true
            });

        // Now return the first 250 entries.
        if (allMovies != null && allMovies.Any())
        {
            moviesList = allMovies.GetRange(0, 250);
        }
        return moviesList;
    }

    /// <summary>
    /// Writes 250 items to the movie table.
    /// </summary>
    /// <param name="movieFileName">A string containing the full path to
    /// the JSON file containing movie data.</param>
    /// <param name="tableName">The name of the table to write items to.</param>
    /// <returns>A long integer value representing the number of movies
    /// imported from the JSON file.</returns>
    public async Task<long> BatchWriteItemsAsync(
        string movieFileName, string tableName)
    {
        try
        {
            var movies = ImportMovies(movieFileName);
            if (!movies.Any())
            {
                Console.WriteLine("Couldn't find the JSON file with movie data.");
                return 0;
            }

            var context = new DynamoDBContextBuilder()
                // Optional call to provide a specific instance of IAmazonDynamoDB
                .WithDynamoDBClient(() => _amazonDynamoDB)
                .Build();

            var movieBatch = context.CreateBatchWrite<Movie>(
                new BatchWriteConfig()
                {
                    OverrideTableName = tableName
                });
            movieBatch.AddPutItems(movies);

            Console.WriteLine("Adding imported movies to the table.");
            await movieBatch.ExecuteAsync();

            return movies.Count;
        }
        catch (ResourceNotFoundException ex)
        {
            Console.WriteLine($"Table was not found during batch write operation. {ex.Message}");
            throw;
        }
        catch (AmazonDynamoDBException ex)
        {
            Console.WriteLine($"An Amazon DynamoDB error occurred during batch write operation. {ex.Message}");
            throw;
        }
        catch (Exception ex)
        {
            Console.WriteLine($"An error occurred during batch write operation. {ex.Message}");
            throw;
        }
    }

Elimina un singolo elemento dalla tabella.

    /// <summary>
    /// Deletes a single item from a DynamoDB table.
    /// </summary>
    /// <param name="tableName">The name of the table from which the item
    /// will be deleted.</param>
    /// <param name="movieToDelete">A movie object containing the title and
    /// year of the movie to delete.</param>
    /// <returns>A Boolean value indicating the success or failure of the
    /// delete operation.</returns>
    public async Task<bool> DeleteItemAsync(
        string tableName,
        Movie movieToDelete)
    {
        try
        {
            var key = new Dictionary<string, AttributeValue>
            {
                ["title"] = new AttributeValue { S = movieToDelete.Title },
                ["year"] = new AttributeValue { N = movieToDelete.Year.ToString() },
            };

            var request = new DeleteItemRequest { TableName = tableName, Key = key, };

            await _amazonDynamoDB.DeleteItemAsync(request);
            return true;
        }
        catch (ResourceNotFoundException ex)
        {
            Console.WriteLine($"Table {tableName} was not found. {ex.Message}");
            return false;
        }
        catch (AmazonDynamoDBException ex)
        {
            Console.WriteLine($"An Amazon DynamoDB error occurred while deleting item. {ex.Message}");
            throw;
        }
        catch (Exception ex)
        {
            Console.WriteLine($"An error occurred while deleting item. {ex.Message}");
            throw;
        }
    }

Esegue una query sulla tabella per i filmati usciti in un determinato anno.

    /// <summary>
    /// Queries the table for movies released in a particular year and
    /// then displays the information for the movies returned.
    /// </summary>
    /// <param name="tableName">The name of the table to query.</param>
    /// <param name="year">The release year for which we want to
    /// view movies.</param>
    /// <returns>The number of movies that match the query.</returns>
    public async Task<int> QueryMoviesAsync(string tableName, int year)
    {
        try
        {
            var movieTable = new TableBuilder(_amazonDynamoDB, tableName)
                .AddHashKey("year", DynamoDBEntryType.Numeric)
                .AddRangeKey("title", DynamoDBEntryType.String)
                .Build();

            var filter = new QueryFilter("year", QueryOperator.Equal, year);

            Console.WriteLine("\nFind movies released in: {year}:");

            var config = new QueryOperationConfig()
            {
                Limit = 10, // 10 items per page.
                Select = SelectValues.SpecificAttributes,
                AttributesToGet = new List<string>
                {
                    "title",
                    "year",
                },
                ConsistentRead = true,
                Filter = filter,
            };

            // Value used to track how many movies match the
            // supplied criteria.
            var moviesFound = 0;

            var search = movieTable.Query(config);
            do
            {
                var movieList = await search.GetNextSetAsync();
                moviesFound += movieList.Count;

                foreach (var movie in movieList)
                {
                    DisplayDocument(movie);
                }
            }
            while (!search.IsDone);

            return moviesFound;
        }
        catch (ResourceNotFoundException ex)
        {
            Console.WriteLine($"Table {tableName} was not found. {ex.Message}");
            return 0;
        }
        catch (AmazonDynamoDBException ex)
        {
            Console.WriteLine($"An Amazon DynamoDB error occurred while querying movies. {ex.Message}");
            throw;
        }
        catch (Exception ex)
        {
            Console.WriteLine($"An error occurred while querying movies. {ex.Message}");
            throw;
        }
    }

Esegue la ricerca dei filmati che sono usciti in un intervallo di anni.

    /// <summary>
    /// Scans the table for movies released between the specified years.
    /// </summary>
    /// <param name="tableName">The name of the table to scan.</param>
    /// <param name="startYear">The starting year for the range.</param>
    /// <param name="endYear">The ending year for the range.</param>
    /// <returns>The number of movies found in the specified year range.</returns>
    public async Task<int> ScanTableAsync(
        string tableName,
        int startYear,
        int endYear)
    {
        try
        {
            var request = new ScanRequest
            {
                TableName = tableName,
                ExpressionAttributeNames = new Dictionary<string, string>
                {
                    { "#yr", "year" },
                },
                ExpressionAttributeValues = new Dictionary<string, AttributeValue>
                {
                    { ":y_a", new AttributeValue { N = startYear.ToString() } },
                    { ":y_z", new AttributeValue { N = endYear.ToString() } },
                },
                FilterExpression = "#yr between :y_a and :y_z",
                ProjectionExpression = "#yr, title, info.actors[0], info.directors, info.running_time_secs",
                Limit = 10 // Set a limit to demonstrate using the LastEvaluatedKey.
            };

            // Keep track of how many movies were found.
            int foundCount = 0;

            var response = new ScanResponse();
            do
            {
                response = await _amazonDynamoDB.ScanAsync(request);
                foundCount += response.Items.Count;
                response.Items.ForEach(i => DisplayItem(i));
                request.ExclusiveStartKey = response.LastEvaluatedKey;
            }
            while (response?.LastEvaluatedKey?.Count > 0);
            return foundCount;
        }
        catch (ResourceNotFoundException ex)
        {
            Console.WriteLine($"Table {tableName} was not found. {ex.Message}");
            return 0;
        }
        catch (AmazonDynamoDBException ex)
        {
            Console.WriteLine($"An Amazon DynamoDB error occurred while scanning table. {ex.Message}");
            throw;
        }
        catch (Exception ex)
        {
            Console.WriteLine($"An error occurred while scanning table. {ex.Message}");
            throw;
        }
    }

Elimina la tabella del filmato.

    /// <summary>
    /// Deletes a DynamoDB table.
    /// </summary>
    /// <param name="tableName">The name of the table to delete.</param>
    /// <returns>A Boolean value indicating the success of the operation.</returns>
    public async Task<bool> DeleteTableAsync(string tableName)
    {
        try
        {
            var request = new DeleteTableRequest
            {
                TableName = tableName,
            };

            var response = await _amazonDynamoDB.DeleteTableAsync(request);

            Console.WriteLine($"Table {response.TableDescription.TableName} successfully deleted.");
            return true;

        }
        catch (ResourceNotFoundException ex)
        {
            Console.WriteLine($"Table {tableName} was not found and cannot be deleted. {ex.Message}");
            return false;
        }
        catch (AmazonDynamoDBException ex)
        {
            Console.WriteLine($"An Amazon DynamoDB error occurred while deleting table {tableName}. {ex.Message}");
            return false;
        }
        catch (Exception ex)
        {
            Console.WriteLine($"An error occurred while deleting table {tableName}. {ex.Message}");
            return false;
        }
    }

Scrive un batch di elementi nella tabella del filmato.

    /// <summary>
    /// Loads the contents of a JSON file into a list of movies to be
    /// added to the DynamoDB table.
    /// </summary>
    /// <param name="movieFileName">The name of the JSON file.</param>
    /// <returns>A generic list of movie objects.</returns>
    public List<Movie> ImportMovies(string movieFileName)
    {
        var moviesList = new List<Movie>();
        if (!File.Exists(movieFileName))
        {
            return moviesList;
        }

        using var sr = new StreamReader(movieFileName);
        string json = sr.ReadToEnd();
        var allMovies = JsonSerializer.Deserialize<List<Movie>>(
            json,
            new JsonSerializerOptions
            {
                PropertyNameCaseInsensitive = true
            });

        // Now return the first 250 entries.
        if (allMovies != null && allMovies.Any())
        {
            moviesList = allMovies.GetRange(0, 250);
        }
        return moviesList;
    }

    /// <summary>
    /// Writes 250 items to the movie table.
    /// </summary>
    /// <param name="movieFileName">A string containing the full path to
    /// the JSON file containing movie data.</param>
    /// <param name="tableName">The name of the table to write items to.</param>
    /// <returns>A long integer value representing the number of movies
    /// imported from the JSON file.</returns>
    public async Task<long> BatchWriteItemsAsync(
        string movieFileName, string tableName)
    {
        try
        {
            var movies = ImportMovies(movieFileName);
            if (!movies.Any())
            {
                Console.WriteLine("Couldn't find the JSON file with movie data.");
                return 0;
            }

            var context = new DynamoDBContextBuilder()
                // Optional call to provide a specific instance of IAmazonDynamoDB
                .WithDynamoDBClient(() => _amazonDynamoDB)
                .Build();

            var movieBatch = context.CreateBatchWrite<Movie>(
                new BatchWriteConfig()
                {
                    OverrideTableName = tableName
                });
            movieBatch.AddPutItems(movies);

            Console.WriteLine("Adding imported movies to the table.");
            await movieBatch.ExecuteAsync();

            return movies.Count;
        }
        catch (ResourceNotFoundException ex)
        {
            Console.WriteLine($"Table was not found during batch write operation. {ex.Message}");
            throw;
        }
        catch (AmazonDynamoDBException ex)
        {
            Console.WriteLine($"An Amazon DynamoDB error occurred during batch write operation. {ex.Message}");
            throw;
        }
        catch (Exception ex)
        {
            Console.WriteLine($"An error occurred during batch write operation. {ex.Message}");
            throw;
        }
    }

    /// <summary>
    /// Creates a new Amazon DynamoDB table and then waits for the new
    /// table to become active.
    /// </summary>
    /// <param name="tableName">The name of the table to create.</param>
    /// <returns>A Boolean value indicating the success of the operation.</returns>
    public async Task<bool> CreateMovieTableAsync(string tableName)
    {
        try
        {
            var response = await _amazonDynamoDB.CreateTableAsync(new CreateTableRequest
            {
                TableName = tableName,
                AttributeDefinitions = new List<AttributeDefinition>()
                {
                    new AttributeDefinition
                    {
                        AttributeName = "title",
                        AttributeType = ScalarAttributeType.S,
                    },
                    new AttributeDefinition
                    {
                        AttributeName = "year",
                        AttributeType = ScalarAttributeType.N,
                    },
                },
                KeySchema = new List<KeySchemaElement>()
                {
                    new KeySchemaElement
                    {
                        AttributeName = "year",
                        KeyType = KeyType.HASH,
                    },
                    new KeySchemaElement
                    {
                        AttributeName = "title",
                        KeyType = KeyType.RANGE,
                    },
                },
                BillingMode = BillingMode.PAY_PER_REQUEST,
            });

            // Wait until the table is ACTIVE and then report success.
            Console.Write("Waiting for table to become active...");

            var request = new DescribeTableRequest
            {
                TableName = response.TableDescription.TableName,
            };

            TableStatus status;

            int sleepDuration = 2000;

            do
            {
                Thread.Sleep(sleepDuration);

                var describeTableResponse = await _amazonDynamoDB.DescribeTableAsync(request);
                status = describeTableResponse.Table.TableStatus;

                Console.Write(".");
            }
            while (status != "ACTIVE");

            return status == TableStatus.ACTIVE;
        }
        catch (ResourceInUseException ex)
        {
            Console.WriteLine($"Table {tableName} already exists. {ex.Message}");
            throw;
        }
        catch (AmazonDynamoDBException ex)
        {
            Console.WriteLine($"An Amazon DynamoDB error occurred while creating table {tableName}. {ex.Message}");
            throw;
        }
        catch (Exception ex)
        {
            Console.WriteLine($"An error occurred while creating table {tableName}. {ex.Message}");
            throw;
        }
    }

    /// <summary>
    /// Deletes a single item from a DynamoDB table.
    /// </summary>
    /// <param name="tableName">The name of the table from which the item
    /// will be deleted.</param>
    /// <param name="movieToDelete">A movie object containing the title and
    /// year of the movie to delete.</param>
    /// <returns>A Boolean value indicating the success or failure of the
    /// delete operation.</returns>
    public async Task<bool> DeleteItemAsync(
        string tableName,
        Movie movieToDelete)
    {
        try
        {
            var key = new Dictionary<string, AttributeValue>
            {
                ["title"] = new AttributeValue { S = movieToDelete.Title },
                ["year"] = new AttributeValue { N = movieToDelete.Year.ToString() },
            };

            var request = new DeleteItemRequest { TableName = tableName, Key = key, };

            await _amazonDynamoDB.DeleteItemAsync(request);
            return true;
        }
        catch (ResourceNotFoundException ex)
        {
            Console.WriteLine($"Table {tableName} was not found. {ex.Message}");
            return false;
        }
        catch (AmazonDynamoDBException ex)
        {
            Console.WriteLine($"An Amazon DynamoDB error occurred while deleting item. {ex.Message}");
            throw;
        }
        catch (Exception ex)
        {
            Console.WriteLine($"An error occurred while deleting item. {ex.Message}");
            throw;
        }
    }

    /// <summary>
    /// Deletes a DynamoDB table.
    /// </summary>
    /// <param name="tableName">The name of the table to delete.</param>
    /// <returns>A Boolean value indicating the success of the operation.</returns>
    public async Task<bool> DeleteTableAsync(string tableName)
    {
        try
        {
            var request = new DeleteTableRequest
            {
                TableName = tableName,
            };

            var response = await _amazonDynamoDB.DeleteTableAsync(request);

            Console.WriteLine($"Table {response.TableDescription.TableName} successfully deleted.");
            return true;

        }
        catch (ResourceNotFoundException ex)
        {
            Console.WriteLine($"Table {tableName} was not found and cannot be deleted. {ex.Message}");
            return false;
        }
        catch (AmazonDynamoDBException ex)
        {
            Console.WriteLine($"An Amazon DynamoDB error occurred while deleting table {tableName}. {ex.Message}");
            return false;
        }
        catch (Exception ex)
        {
            Console.WriteLine($"An error occurred while deleting table {tableName}. {ex.Message}");
            return false;
        }
    }

    /// <summary>
    /// Gets information about an existing movie from the table.
    /// </summary>
    /// <param name="newMovie">A Movie object containing information about
    /// the movie to retrieve.</param>
    /// <param name="tableName">The name of the table containing the movie.</param>
    /// <returns>A Dictionary object containing information about the item
    /// retrieved.</returns>
    public async Task<Dictionary<string, AttributeValue>> GetItemAsync(Movie newMovie, string tableName)
    {
        try
        {
            var key = new Dictionary<string, AttributeValue>
            {
                ["title"] = new AttributeValue { S = newMovie.Title },
                ["year"] = new AttributeValue { N = newMovie.Year.ToString() },
            };

            var request = new GetItemRequest
            {
                Key = key,
                TableName = tableName,
            };

            var response = await _amazonDynamoDB.GetItemAsync(request);
            return response.Item;
        }
        catch (ResourceNotFoundException ex)
        {
            Console.WriteLine($"Table {tableName} was not found. {ex.Message}");
            return new Dictionary<string, AttributeValue>();
        }
        catch (AmazonDynamoDBException ex)
        {
            Console.WriteLine($"An Amazon DynamoDB error occurred while getting item. {ex.Message}");
            throw;
        }
        catch (Exception ex)
        {
            Console.WriteLine($"An error occurred while getting item. {ex.Message}");
            throw;
        }
    }

    /// <summary>
    /// Adds a new item to the table.
    /// </summary>
    /// <param name="newMovie">A Movie object containing informtation for
    /// the movie to add to the table.</param>
    /// <param name="tableName">The name of the table where the item will be added.</param>
    /// <returns>A Boolean value that indicates the results of adding the item.</returns>
    public async Task<bool> PutItemAsync(Movie newMovie, string tableName)
    {
        try
        {
            var item = new Dictionary<string, AttributeValue>
            {
                ["title"] = new AttributeValue { S = newMovie.Title },
                ["year"] = new AttributeValue { N = newMovie.Year.ToString() },
            };

            var request = new PutItemRequest
            {
                TableName = tableName,
                Item = item,
            };

            await _amazonDynamoDB.PutItemAsync(request);
            return true;
        }
        catch (ResourceNotFoundException ex)
        {
            Console.WriteLine($"Table {tableName} was not found. {ex.Message}");
            return false;
        }
        catch (AmazonDynamoDBException ex)
        {
            Console.WriteLine($"An Amazon DynamoDB error occurred while putting item. {ex.Message}");
            throw;
        }
        catch (Exception ex)
        {
            Console.WriteLine($"An error occurred while putting item. {ex.Message}");
            throw;
        }
    }

    /// <summary>
    /// Queries the table for movies released in a particular year and
    /// then displays the information for the movies returned.
    /// </summary>
    /// <param name="tableName">The name of the table to query.</param>
    /// <param name="year">The release year for which we want to
    /// view movies.</param>
    /// <returns>The number of movies that match the query.</returns>
    public async Task<int> QueryMoviesAsync(string tableName, int year)
    {
        try
        {
            var movieTable = new TableBuilder(_amazonDynamoDB, tableName)
                .AddHashKey("year", DynamoDBEntryType.Numeric)
                .AddRangeKey("title", DynamoDBEntryType.String)
                .Build();

            var filter = new QueryFilter("year", QueryOperator.Equal, year);

            Console.WriteLine("\nFind movies released in: {year}:");

            var config = new QueryOperationConfig()
            {
                Limit = 10, // 10 items per page.
                Select = SelectValues.SpecificAttributes,
                AttributesToGet = new List<string>
                {
                    "title",
                    "year",
                },
                ConsistentRead = true,
                Filter = filter,
            };

            // Value used to track how many movies match the
            // supplied criteria.
            var moviesFound = 0;

            var search = movieTable.Query(config);
            do
            {
                var movieList = await search.GetNextSetAsync();
                moviesFound += movieList.Count;

                foreach (var movie in movieList)
                {
                    DisplayDocument(movie);
                }
            }
            while (!search.IsDone);

            return moviesFound;
        }
        catch (ResourceNotFoundException ex)
        {
            Console.WriteLine($"Table {tableName} was not found. {ex.Message}");
            return 0;
        }
        catch (AmazonDynamoDBException ex)
        {
            Console.WriteLine($"An Amazon DynamoDB error occurred while querying movies. {ex.Message}");
            throw;
        }
        catch (Exception ex)
        {
            Console.WriteLine($"An error occurred while querying movies. {ex.Message}");
            throw;
        }
    }

    /// <summary>
    /// Scans the table for movies released between the specified years.
    /// </summary>
    /// <param name="tableName">The name of the table to scan.</param>
    /// <param name="startYear">The starting year for the range.</param>
    /// <param name="endYear">The ending year for the range.</param>
    /// <returns>The number of movies found in the specified year range.</returns>
    public async Task<int> ScanTableAsync(
        string tableName,
        int startYear,
        int endYear)
    {
        try
        {
            var request = new ScanRequest
            {
                TableName = tableName,
                ExpressionAttributeNames = new Dictionary<string, string>
                {
                    { "#yr", "year" },
                },
                ExpressionAttributeValues = new Dictionary<string, AttributeValue>
                {
                    { ":y_a", new AttributeValue { N = startYear.ToString() } },
                    { ":y_z", new AttributeValue { N = endYear.ToString() } },
                },
                FilterExpression = "#yr between :y_a and :y_z",
                ProjectionExpression = "#yr, title, info.actors[0], info.directors, info.running_time_secs",
                Limit = 10 // Set a limit to demonstrate using the LastEvaluatedKey.
            };

            // Keep track of how many movies were found.
            int foundCount = 0;

            var response = new ScanResponse();
            do
            {
                response = await _amazonDynamoDB.ScanAsync(request);
                foundCount += response.Items.Count;
                response.Items.ForEach(i => DisplayItem(i));
                request.ExclusiveStartKey = response.LastEvaluatedKey;
            }
            while (response?.LastEvaluatedKey?.Count > 0);
            return foundCount;
        }
        catch (ResourceNotFoundException ex)
        {
            Console.WriteLine($"Table {tableName} was not found. {ex.Message}");
            return 0;
        }
        catch (AmazonDynamoDBException ex)
        {
            Console.WriteLine($"An Amazon DynamoDB error occurred while scanning table. {ex.Message}");
            throw;
        }
        catch (Exception ex)
        {
            Console.WriteLine($"An error occurred while scanning table. {ex.Message}");
            throw;
        }
    }

    /// <summary>
    /// Updates an existing item in the movies table.
    /// </summary>
    /// <param name="newMovie">A Movie object containing information for
    /// the movie to update.</param>
    /// <param name="newInfo">A MovieInfo object that contains the
    /// information that will be changed.</param>
    /// <param name="tableName">The name of the table that contains the movie.</param>
    /// <returns>A Boolean value that indicates the success of the operation.</returns>
    public async Task<bool> UpdateItemAsync(
        Movie newMovie,
        MovieInfo newInfo,
        string tableName)
    {
        try
        {
            var key = new Dictionary<string, AttributeValue>
            {
                ["title"] = new AttributeValue { S = newMovie.Title },
                ["year"] = new AttributeValue { N = newMovie.Year.ToString() },
            };
            var updates = new Dictionary<string, AttributeValueUpdate>
            {
                ["info.plot"] = new AttributeValueUpdate
                {
                    Action = AttributeAction.PUT,
                    Value = new AttributeValue { S = newInfo.Plot },
                },

                ["info.rating"] = new AttributeValueUpdate
                {
                    Action = AttributeAction.PUT,
                    Value = new AttributeValue { N = newInfo.Rank.ToString() },
                },
            };

            var request = new UpdateItemRequest
            {
                AttributeUpdates = updates,
                Key = key,
                TableName = tableName,
            };

            await _amazonDynamoDB.UpdateItemAsync(request);
            return true;
        }
        catch (ResourceNotFoundException ex)
        {
            Console.WriteLine($"Table {tableName} or item was not found. {ex.Message}");
            return false;
        }
        catch (AmazonDynamoDBException ex)
        {
            Console.WriteLine($"An Amazon DynamoDB error occurred while updating item. {ex.Message}");
            throw;
        }
        catch (Exception ex)
        {
            Console.WriteLine($"An error occurred while updating item. {ex.Message}");
            throw;
        }
    }