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DynamoDB examples using SDK for .NET

The following code examples show you how to perform actions and implement common scenarios by using the AWS SDK for .NET with DynamoDB.

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.

AWS community contributions are examples that were created and are maintained by multiple teams across AWS. To provide feedback, use the mechanism provided in the linked repositories.

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.

Actions

The following code example shows how to use BatchExecuteStatement.

SDK for .NET

Note

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

Use batches of INSERT statements to add items.


        /// <summary>
        /// Inserts movies imported from a JSON file into the movie table by
        /// using an Amazon DynamoDB PartiQL INSERT statement.
        /// </summary>
        /// <param name="tableName">The name of the table into which the movie
        /// information will be inserted.</param>
        /// <param name="movieFileName">The name of the JSON file that contains
        /// movie information.</param>
        /// <returns>A Boolean value that indicates the success or failure of
        /// the insert operation.</returns>
        public static async Task<bool> InsertMovies(string tableName, string movieFileName)
        {
            // Get the list of movies from the JSON file.
            var movies = ImportMovies(movieFileName);

            var success = false;

            if (movies is not null)
            {
                // Insert the movies in a batch using PartiQL. Because the
                // batch can contain a maximum of 25 items, insert 25 movies
                // at a time.
                string insertBatch = $"INSERT INTO {tableName} VALUE {{'title': ?, 'year': ?}}";
                var statements = new List<BatchStatementRequest>();

                try
                {
                    for (var indexOffset = 0; indexOffset < 250; indexOffset += 25)
                    {
                        for (var i = indexOffset; i < indexOffset + 25; i++)
                        {
                            statements.Add(new BatchStatementRequest
                            {
                                Statement = insertBatch,
                                Parameters = new List<AttributeValue>
                                {
                                    new AttributeValue { S = movies[i].Title },
                                    new AttributeValue { N = movies[i].Year.ToString() },
                                },
                            });
                        }

                        var response = await Client.BatchExecuteStatementAsync(new BatchExecuteStatementRequest
                        {
                            Statements = statements,
                        });

                        // Wait between batches for movies to be successfully added.
                        System.Threading.Thread.Sleep(3000);

                        success = response.HttpStatusCode == System.Net.HttpStatusCode.OK;

                        // Clear the list of statements for the next batch.
                        statements.Clear();
                    }
                }
                catch (AmazonDynamoDBException ex)
                {
                    Console.WriteLine(ex.Message);
                }
            }

            return success;
        }

        /// <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 full path to the JSON file.</param>
        /// <returns>A generic list of movie objects.</returns>
        public static List<Movie> ImportMovies(string movieFileName)
        {
            if (!File.Exists(movieFileName))
            {
                return null!;
            }

            using var sr = new StreamReader(movieFileName);
            string json = sr.ReadToEnd();
            var allMovies = JsonConvert.DeserializeObject<List<Movie>>(json);

            if (allMovies is not null)
            {
                // Return the first 250 entries.
                return allMovies.GetRange(0, 250);
            }
            else
            {
                return null!;
            }
        }

Use batches of SELECT statements to get items.


        /// <summary>
        /// Gets movies from the movie table by
        /// using an Amazon DynamoDB PartiQL SELECT statement.
        /// </summary>
        /// <param name="tableName">The name of the table.</param>
        /// <param name="title1">The title of the first movie.</param>
        /// <param name="title2">The title of the second movie.</param>
        /// <param name="year1">The year of the first movie.</param>
        /// <param name="year2">The year of the second movie.</param>
        /// <returns>True if successful.</returns>
        public static async Task<bool> GetBatch(
            string tableName,
            string title1,
            string title2,
            int year1,
            int year2)
        {
            var getBatch = $"SELECT * FROM {tableName} WHERE title = ? AND year = ?";
            var statements = new List<BatchStatementRequest>
            {
                new BatchStatementRequest
                {
                    Statement = getBatch,
                    Parameters = new List<AttributeValue>
                    {
                        new AttributeValue { S = title1 },
                        new AttributeValue { N = year1.ToString() },
                    },
                },

                new BatchStatementRequest
                {
                    Statement = getBatch,
                    Parameters = new List<AttributeValue>
                    {
                        new AttributeValue { S = title2 },
                        new AttributeValue { N = year2.ToString() },
                    },
                }
            };

            var response = await Client.BatchExecuteStatementAsync(new BatchExecuteStatementRequest
            {
                Statements = statements,
            });

            if (response.Responses.Count > 0)
            {
                response.Responses.ForEach(r =>
                {
                    if (r.Item.Any())
                    {
                        Console.WriteLine($"{r.Item["title"]}\t{r.Item["year"]}");
                    }
                });
                return true;
            }
            else
            {
                Console.WriteLine($"Couldn't find either {title1} or {title2}.");
                return false;
            }

        }

Use batches of UPDATE statements to update items.


        /// <summary>
        /// Updates information for multiple movies.
        /// </summary>
        /// <param name="tableName">The name of the table containing the
        /// movies to be updated.</param>
        /// <param name="producer1">The producer name for the first movie
        /// to update.</param>
        /// <param name="title1">The title of the first movie.</param>
        /// <param name="year1">The year that the first movie was released.</param>
        /// <param name="producer2">The producer name for the second
        /// movie to update.</param>
        /// <param name="title2">The title of the second movie.</param>
        /// <param name="year2">The year that the second movie was released.</param>
        /// <returns>A Boolean value that indicates the success of the update.</returns>
        public static async Task<bool> UpdateBatch(
            string tableName,
            string producer1,
            string title1,
            int year1,
            string producer2,
            string title2,
            int year2)
        {

            string updateBatch = $"UPDATE {tableName} SET Producer=? WHERE title = ? AND year = ?";
            var statements = new List<BatchStatementRequest>
            {
                new BatchStatementRequest
                {
                    Statement = updateBatch,
                    Parameters = new List<AttributeValue>
                    {
                        new AttributeValue { S = producer1 },
                        new AttributeValue { S = title1 },
                        new AttributeValue { N = year1.ToString() },
                    },
                },

                new BatchStatementRequest
                {
                    Statement = updateBatch,
                    Parameters = new List<AttributeValue>
                    {
                        new AttributeValue { S = producer2 },
                        new AttributeValue { S = title2 },
                        new AttributeValue { N = year2.ToString() },
                    },
                }
            };

            var response = await Client.BatchExecuteStatementAsync(new BatchExecuteStatementRequest
            {
                Statements = statements,
            });

            return response.HttpStatusCode == System.Net.HttpStatusCode.OK;
        }

Use batches of DELETE statements to delete items.


        /// <summary>
        /// Deletes multiple movies using a PartiQL BatchExecuteAsync
        /// statement.
        /// </summary>
        /// <param name="tableName">The name of the table containing the
        /// moves that will be deleted.</param>
        /// <param name="title1">The title of the first movie.</param>
        /// <param name="year1">The year the first movie was released.</param>
        /// <param name="title2">The title of the second movie.</param>
        /// <param name="year2">The year the second movie was released.</param>
        /// <returns>A Boolean value indicating the success of the operation.</returns>
        public static async Task<bool> DeleteBatch(
            string tableName,
            string title1,
            int year1,
            string title2,
            int year2)
        {

            string updateBatch = $"DELETE FROM {tableName} WHERE title = ? AND year = ?";
            var statements = new List<BatchStatementRequest>
            {
                new BatchStatementRequest
                {
                    Statement = updateBatch,
                    Parameters = new List<AttributeValue>
                    {
                        new AttributeValue { S = title1 },
                        new AttributeValue { N = year1.ToString() },
                    },
                },

                new BatchStatementRequest
                {
                    Statement = updateBatch,
                    Parameters = new List<AttributeValue>
                    {
                        new AttributeValue { S = title2 },
                        new AttributeValue { N = year2.ToString() },
                    },
                }
            };

            var response = await Client.BatchExecuteStatementAsync(new BatchExecuteStatementRequest
            {
                Statements = statements,
            });

            return response.HttpStatusCode == System.Net.HttpStatusCode.OK;
        }

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

The following code example shows how to use BatchGetItem.

SDK for .NET

Note

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


using System;
using System.Collections.Generic;
using Amazon.DynamoDBv2;
using Amazon.DynamoDBv2.Model;

namespace LowLevelBatchGet
{
    public class LowLevelBatchGet
    {
        private static readonly string _table1Name = "Forum";
        private static readonly string _table2Name = "Thread";

        public static async void RetrieveMultipleItemsBatchGet(AmazonDynamoDBClient client)
        {
            var request = new BatchGetItemRequest
            {
                RequestItems = new Dictionary<string, KeysAndAttributes>()
            {
                { _table1Name,
                  new KeysAndAttributes
                  {
                      Keys = new List<Dictionary<string, AttributeValue> >()
                      {
                          new Dictionary<string, AttributeValue>()
                          {
                              { "Name", new AttributeValue {
                            S = "Amazon DynamoDB"
                        } }
                          },
                          new Dictionary<string, AttributeValue>()
                          {
                              { "Name", new AttributeValue {
                            S = "Amazon S3"
                        } }
                          }
                      }
                  }},
                {
                    _table2Name,
                    new KeysAndAttributes
                    {
                        Keys = new List<Dictionary<string, AttributeValue> >()
                        {
                            new Dictionary<string, AttributeValue>()
                            {
                                { "ForumName", new AttributeValue {
                                      S = "Amazon DynamoDB"
                                  } },
                                { "Subject", new AttributeValue {
                                      S = "DynamoDB Thread 1"
                                  } }
                            },
                            new Dictionary<string, AttributeValue>()
                            {
                                { "ForumName", new AttributeValue {
                                      S = "Amazon DynamoDB"
                                  } },
                                { "Subject", new AttributeValue {
                                      S = "DynamoDB Thread 2"
                                  } }
                            },
                            new Dictionary<string, AttributeValue>()
                            {
                                { "ForumName", new AttributeValue {
                                      S = "Amazon S3"
                                  } },
                                { "Subject", new AttributeValue {
                                      S = "S3 Thread 1"
                                  } }
                            }
                        }
                    }
                }
            }
            };

            BatchGetItemResponse response;
            do
            {
                Console.WriteLine("Making request");
                response = await client.BatchGetItemAsync(request);

                // Check the response.
                var responses = response.Responses; // Attribute list in the response.

                foreach (var tableResponse in responses)
                {
                    var tableResults = tableResponse.Value;
                    Console.WriteLine("Items retrieved from table {0}", tableResponse.Key);
                    foreach (var item1 in tableResults)
                    {
                        PrintItem(item1);
                    }
                }

                // Any unprocessed keys? could happen if you exceed ProvisionedThroughput or some other error.
                Dictionary<string, KeysAndAttributes> unprocessedKeys = response.UnprocessedKeys;
                foreach (var unprocessedTableKeys in unprocessedKeys)
                {
                    // Print table name.
                    Console.WriteLine(unprocessedTableKeys.Key);
                    // Print unprocessed primary keys.
                    foreach (var key in unprocessedTableKeys.Value.Keys)
                    {
                        PrintItem(key);
                    }
                }

                request.RequestItems = unprocessedKeys;
            } while (response.UnprocessedKeys.Count > 0);
        }

        private static void PrintItem(Dictionary<string, AttributeValue> attributeList)
        {
            foreach (KeyValuePair<string, AttributeValue> kvp in attributeList)
            {
                string attributeName = kvp.Key;
                AttributeValue value = kvp.Value;

                Console.WriteLine(
                    attributeName + " " +
                    (value.S == null ? "" : "S=[" + value.S + "]") +
                    (value.N == null ? "" : "N=[" + value.N + "]") +
                    (value.SS == null ? "" : "SS=[" + string.Join(",", value.SS.ToArray()) + "]") +
                    (value.NS == null ? "" : "NS=[" + string.Join(",", value.NS.ToArray()) + "]")
                    );
            }
            Console.WriteLine("************************************************");
        }

        static void Main()
        {
            var client = new AmazonDynamoDBClient();

            RetrieveMultipleItemsBatchGet(client);
        }
    }
}

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

The following code example shows how to use DescribeTable.

SDK for .NET

Note

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


    private static async Task GetTableInformation()
    {
        Console.WriteLine("\n*** Retrieving table information ***");

        var response = await Client.DescribeTableAsync(new DescribeTableRequest
        {
            TableName = ExampleTableName
        });

        var table = response.Table;
        Console.WriteLine($"Name: {table.TableName}");
        Console.WriteLine($"# of items: {table.ItemCount}");

    }

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

The following code example shows how to use ExecuteStatement.

SDK for .NET