Update many records in one call

Runs the sample. Generated for this page; it reads the connection string from the environment and first remakes the sample database from sample-schema.json.

using ArxSamples.DynamoDb;
using ArxSamples.DynamoDb.Operations.UpdateMultiple.Basics;

// The connection string comes from the environment, never from the code (see "Configure the connection").
var connectionString = Environment.GetEnvironmentVariable("ARX_SAMPLES_DYNAMODB")
    ?? throw new InvalidOperationException("Set the ARX_SAMPLES_DYNAMODB environment variable to your Amazon DynamoDB connection string.");

var dbContext = new SampleContext(connectionString);

// Every run starts from the sample data: this deletes and makes again what sample-schema.json lists
// (save the file in the project folder, see Get started).
await dbContext.Direct.ResetAsync();

await new Basic1_UpdateManyRecords().RunAsync(dbContext);

The sample, as it is in the repository.

using ARX.SDK;
using ARX.SDK.DynamoDb.Services;
using ARX.SDK.Services;

using static ArxSamples.DynamoDb.SampleOutput;

namespace ArxSamples.DynamoDb.Operations.UpdateMultiple.Basics;

/// <summary>
/// Many items in one call, all or nothing, in two scenarios: a different price for each product, and a list with one
/// SKU no item has, where none of them changes.
/// </summary>
/// <remarks>
/// The updates go as one <c>TransactWriteItems</c>, each conditional on its item existing: at most 100 items in a call
/// (more is ARX8001 unless <c>AllowPartial</c>). Each entity writes only the attributes it sets.
/// </remarks>
public sealed class Basic1_UpdateManyRecords : ISample
{
    public string Name => "update-multiple-basics-1-update-many-records";

    public string Title => "Update many records in one call";

    public async Task RunAsync(SampleContext dbContext)
    {
        var products = new[] { "SKU-D271", "SKU-D272", "SKU-D273" }.Select(sku =>
        {
            var product = new ArxEntity("product");
            product["sku"] = sku;
            product["name"] = $"Trail sock {sku}";
            product["price"] = 12.00m;
            return product;
        }).ToList();

        var ids = await dbContext.Service.CreateMultipleAsync(products);

        await Scenario1_APricePerProductAsync(dbContext.Service, ids);

        await Scenario2_AllOrNothingAsync(dbContext.Service);
    }

    /// <summary>1. One entity per item, each with its own price, in one transaction.</summary>
    private static async Task Scenario1_APricePerProductAsync(ArxDynamoDbService service, IReadOnlyList<ArxRecordId> ids)
    {
        Step("1. A price per product");

        var changes = new List<ArxEntity>();

        for (var i = 0; i < ids.Count; i++)
        {
            var change = new ArxEntity("product") { RecordId = ids[i] };
            change["price"] = 10.00m + i;
            changes.Add(change);
        }

        int changed = await service.UpdateMultipleAsync(changes);

        Show($"{changed} items changed in one call");

        /* ===========================================================
         * [DIRECT QUERY CHECK]
         * -----------------------------------------------------------
         * SELECT "sku", "price" FROM "product" WHERE "sku" IN ['SKU-D271', 'SKU-D272', 'SKU-D273']
         * -- Expect: 3 items, price 10, 11, 12.
         * ===========================================================
         */
    }

    /// <summary>2. SKU-D279 is no item: RecordNotFound, and SKU-D271 keeps its price too.</summary>
    private static async Task Scenario2_AllOrNothingAsync(ArxDynamoDbService service)
    {
        Step("2. All or nothing");

        var first = new ArxEntity("product");
        first["sku"] = "SKU-D271";
        first["price"] = 99.00m;

        var missing = new ArxEntity("product");
        missing["sku"] = "SKU-D279";
        missing["price"] = 99.00m;

        try
        {
            await service.UpdateMultipleAsync(new[] { first, missing });
        }
        catch (ArxException exception) when (exception.Code == ArxErrorCode.RecordNotFound)
        {
            ShowError(exception);
        }

        /* ===========================================================
         * [DIRECT QUERY CHECK]
         * -----------------------------------------------------------
         * SELECT "sku", "price" FROM "product" WHERE "sku" IN ['SKU-D271', 'SKU-D279']
         * -- Expect: 1 item, SKU-D271, price 10 (not 99).
         * ===========================================================
         */
    }
}

  > 1. A price per product
      3 items changed in one call
  > 2. All or nothing
      caught ArxDatabaseException: ARX2002 RecordNotFound: UpdateMultiple of 'product': item 1: no item has the key. Nothing was written.