Reprice 20,000 products from a feed

Runs the sample. Generated for this page; it reads the connection string from the environment.

using ArxSamples.MySQL;
using ArxSamples.MySQL.Operations.UpdateMultiple.RealCases;

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

await new RealCase2_RepriceTheCatalog().RunAsync(new SampleContext(connectionString));

The sample, as it is in the repository.

using ARX.SDK;
using ARX.SDK.Services;
using static ArxSamples.MySQL.SampleOutput;

namespace ArxSamples.MySQL.Operations.UpdateMultiple.RealCases;

/// <summary>
/// A supplier's price feed reprices the catalogue, in two scenarios: 20,000 products by SKU in one call (one set-based
/// statement), and a feed with a SKU the catalogue doesn't have, which changes nothing.
/// </summary>
public sealed class RealCase2_RepriceTheCatalog : ISample
{
    private const int PRODUCTS = 20_000;

    public string Name => "update-multiple-real-2-reprice-the-catalog";

    public string Title => "Reprice 20,000 products from a feed";

    public async Task RunAsync(SampleContext dbContext)
    {
        var products = Enumerable.Range(1, PRODUCTS).Select(i =>
        {
            var product = new ArxEntity("product");
            product["sku"] = $"SKU-U8{i:000000}";
            product["name"] = $"Feed product {i}";
            product["unit_price"] = 10.00m;
            return product;
        }).ToList();
        await dbContext.Service.CreateMultipleAsync(products);

        await Scenario1_TheWholeFeedAsync(dbContext);

        await Scenario2_AFeedWithAnUnknownSkuAsync(dbContext);
    }

    /// <summary>1. Every line of the feed is one entity, found by its SKU (the declared key). All of them go in one statement.</summary>
    private static async Task Scenario1_TheWholeFeedAsync(SampleContext dbContext)
    {
        Step("1. The whole feed, by SKU");

        var feed = Enumerable.Range(1, PRODUCTS).Select(i => (Sku: $"SKU-U8{i:000000}", Price: 10.00m + i % 100 / 100m));

        var prices = feed.Select(line =>
        {
            var price = new ArxEntity("product");
            price["sku"] = line.Sku;
            price["unit_price"] = line.Price;
            return price;
        }).ToList();

        var started = DateTime.UtcNow;
        var changed = await dbContext.Service.UpdateMultipleAsync(prices, new ArxUpdateOptions { Match = ArxMatch.Key("sku") });
        Show($"{changed} prices changed in {(DateTime.UtcNow - started).TotalMilliseconds:0} ms");

        /* ===========================================================
         * [DIRECT QUERY CHECK]
         * -----------------------------------------------------------
         * SELECT count(*) AS products, min(unit_price), max(unit_price)
         * FROM product
         * WHERE sku LIKE 'SKU-U8%';
         * -- Expect: 20000, 10.00, 10.99.
         * ===========================================================
         */
    }

    /// <summary>2. One SKU in the feed isn't in the catalogue: the call refuses the whole feed, so no price is half-applied.</summary>
    private static async Task Scenario2_AFeedWithAnUnknownSkuAsync(SampleContext dbContext)
    {
        Step("2. A feed with an unknown SKU");

        var prices = new[] { ("SKU-U8000001", 99.00m), ("SKU-U8000002", 99.00m), ("SKU-NOT-IN-CATALOG", 99.00m) }.Select(line =>
        {
            var price = new ArxEntity("product");
            price["sku"] = line.Item1;
            price["unit_price"] = line.Item2;
            return price;
        }).ToList();

        try
        {
            await dbContext.Service.UpdateMultipleAsync(prices, new ArxUpdateOptions { Match = ArxMatch.Key("sku") });
        }
        catch (ArxException error) when (error.Code == ArxErrorCode.RecordNotFound)
        {
            ShowError(error);
        }

        /* ===========================================================
         * [DIRECT QUERY CHECK]
         * -----------------------------------------------------------
         * SELECT count(*)
         * FROM product
         * WHERE sku LIKE 'SKU-U8%' AND unit_price = 99.00;
         * -- Expect: 0: the two known SKUs weren't repriced either.
         * ===========================================================
         */
    }
}

  > 1. The whole feed, by SKU
      20000 prices changed in 6302 ms
  > 2. A feed with an unknown SKU
      caught ArxException: ARX2002 RecordNotFound: UpdateMultiple on 'product': at least 1 of 3 entities matched no row (the check stops at the first statement with one missing). Nothing was changed.