Catch the errors a create meets

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.Create.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 Basic2_CatchAnError().RunAsync(dbContext);

The sample, as it is in the repository.

using Amazon.DynamoDBv2;
using ARX.SDK;
using ARX.SDK.DynamoDb.Model;
using ARX.SDK.DynamoDb.Services;
using ARX.SDK.Services;

using static ArxSamples.DynamoDb.SampleOutput;

namespace ArxSamples.DynamoDb.Operations.Create.Basics;

/// <summary>
/// The errors a create meets most, in three scenarios: a key that exists, a key attribute left out, and an id declared
/// as generated, which DynamoDB can't do.
/// </summary>
public sealed class Basic2_CatchAnError : ISample
{
    public string Name => "create-basics-2-catch-an-error";

    public string Title => "Catch the errors a create meets";

    public async Task RunAsync(SampleContext dbContext)
    {
        await Scenario1_AKeyThatExistsAsync(dbContext.Service);

        await Scenario2_AKeyAttributeLeftOutAsync(dbContext.Service);

        await Scenario3_AGeneratedIdAsync(dbContext.Client);
    }

    /// <summary>1. The same customer twice: ARX3001; the first stays as it was.</summary>
    private static async Task Scenario1_AKeyThatExistsAsync(ArxDynamoDbService service)
    {
        Step("1. A key that exists");

        var customer = new ArxEntity("customer");
        customer["customer_id"] = "C-D401";
        customer["name"] = "Fabrikam";
        await service.CreateAsync(customer);

        customer["name"] = "Fabrikam (copy)";

        try
        {
            await service.CreateAsync(customer);
        }
        catch (ArxDatabaseException exception) when (exception.Code == ArxErrorCode.UniqueViolation)
        {
            ShowError(exception);
        }

        /* ===========================================================
         * [DIRECT QUERY CHECK]
         * -----------------------------------------------------------
         * SELECT "name" FROM "crm" WHERE "PK" = 'CUSTOMER#C-D401' AND "SK" = 'PROFILE'
         * -- Expect: 1 item, name "Fabrikam".
         * ===========================================================
         */
    }

    /// <summary>2. An order without its customer_id: its key can't be made, so nothing is sent.</summary>
    private static async Task Scenario2_AKeyAttributeLeftOutAsync(ArxDynamoDbService service)
    {
        Step("2. A key attribute left out");

        var order = new ArxEntity("sales_order");
        order["order_number"] = "SO-D402";

        try
        {
            await service.CreateAsync(order);
        }
        catch (ArxValidationException exception)
        {
            ShowError(exception);
        }

        /* ===========================================================
         * [DIRECT QUERY CHECK]
         * -----------------------------------------------------------
         * SELECT "SK" FROM "crm" WHERE "SK" = 'ORDER#SO-D402'
         * -- Expect: no items.
         * ===========================================================
         */
    }

    /// <summary>3. An id declared as generated: DynamoDB generates nothing, so ARX8001 with the advice to supply one.</summary>
    private static async Task Scenario3_AGeneratedIdAsync(IAmazonDynamoDB client)
    {
        Step("3. A generated id");

        var catalog = ArxSchemaCatalog.Create().Table("product", ArxIdColumn.Generated<string>("sku")).Build();
        var service = new ArxDynamoDbService(client, ArxDynamoModel.Create().Table("product", partitionKey: "sku").Build(), catalog);

        var product = new ArxEntity("product");
        product["sku"] = "SKU-D403";

        try
        {
            await service.CreateAsync(product);
        }
        catch (ArxNotSupportedException exception)
        {
            ShowError(exception);
        }

        /* ===========================================================
         * [DIRECT QUERY CHECK]
         * -----------------------------------------------------------
         * SELECT "sku" FROM "product" WHERE "sku" = 'SKU-D403'
         * -- Expect: no items.
         * ===========================================================
         */
    }
}

  > 1. A key that exists
      caught ArxDatabaseException: ARX3001 UniqueViolation: Create of 'customer': an item with the same key already exists.
  > 2. A key attribute left out
      caught ArxValidationException: ARX1001 InvalidArgument: 'sales_order' needs 'customer_id' for its key (customer_id, order_number).
  > 3. A generated id
      caught ArxNotSupportedException: ARX8001 NotSupported: 'product' declares id 'sku' as generated, and DynamoDB generates no ids. Give the id yourself and declare it ArxIdColumn.Supplied<String>("sku"), with a value such as Guid.CreateVersion7().