Choose how the documents are found

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.MongoDb;
using ArxSamples.MongoDb.Operations.Delete.Basics;

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

The sample, as it is in the repository.

using ARX.SDK;
using ARX.SDK.MongoDb.Services;
using ARX.SDK.Services;

using static ArxSamples.MongoDb.SampleOutput;

namespace ArxSamples.MongoDb.Operations.Delete.Basics;

/// <summary>
/// Delete by a key or by any fields, in three scenarios: a compound key, every document with a field's value, and
/// RequireSingleRow, which refuses to delete several.
/// </summary>
/// <remarks>Finding nothing is a normal outcome (0) unless RequireSingleRow is on; then it is ARX2002, and several ARX2003.</remarks>
public sealed class Basic2_HowToFindTheRows : ISample
{
    public string Name => "delete-basics-2-how-to-find-the-rows";

    public string Title => "Choose how the documents are found";

    public async Task RunAsync(SampleContext dbContext)
    {
        foreach (var (region, sku) in new[] { ("PT", "SKU-M911"), ("PT", "SKU-M912"), ("ES", "SKU-M911") })
        {
            var price = new ArxEntity("price_list");
            price["region"] = region;
            price["sku"] = sku;
            price["unit_price"] = 10m;
            price["batch"] = "M91";
            await dbContext.Service.CreateAsync(price);
        }

        await Scenario1_ByACompoundKeyAsync(dbContext.Service);

        await Scenario2_RequireOneAsync(dbContext.Service);

        await Scenario3_ByAnyFieldsAsync(dbContext.Service);
    }

    /// <summary>1. The price of SKU-M911 in PT, by the region and SKU together.</summary>
    private static async Task Scenario1_ByACompoundKeyAsync(ArxMongoDbService service)
    {
        Step("1. By a compound key");

        var match = new ArxEntity("price_list");
        match["region"] = "PT";
        match["sku"] = "SKU-M911";

        int deleted = await service.DeleteAsync(match, new ArxDeleteOptions { Match = ArxMatch.Key("region", "sku") });

        Show($"{deleted} price deleted");

        /* ===========================================================
         * [DIRECT QUERY CHECK]
         * -----------------------------------------------------------
         * db.price_list.find({ batch: "M91" }, { region: 1, sku: 1 })
         * -- Expect: 2 documents: PT SKU-M912, ES SKU-M911.
         * ===========================================================
         */
    }

    /// <summary>2. RequireSingleRow with a field two documents share: ARX2003, nothing deleted.</summary>
    private static async Task Scenario2_RequireOneAsync(ArxMongoDbService service)
    {
        Step("2. Require exactly one");

        var match = new ArxEntity("price_list");
        match["batch"] = "M91";

        try
        {
            await service.DeleteAsync(match, new ArxDeleteOptions { Match = ArxMatch.Columns("batch"), RequireSingleRow = true });
        }
        catch (ArxException exception) when (exception.Code == ArxErrorCode.MultipleRecordsMatched)
        {
            ShowError(exception);
        }

        /* ===========================================================
         * [DIRECT QUERY CHECK]
         * -----------------------------------------------------------
         * db.price_list.countDocuments({ batch: "M91" })
         * -- Expect: 2.
         * ===========================================================
         */
    }

    /// <summary>3. Every price of the batch.</summary>
    private static async Task Scenario3_ByAnyFieldsAsync(ArxMongoDbService service)
    {
        Step("3. By any fields");

        var match = new ArxEntity("price_list");
        match["batch"] = "M91";

        int deleted = await service.DeleteAsync(match, new ArxDeleteOptions { Match = ArxMatch.Columns("batch") });

        Show($"{deleted} prices deleted");

        /* ===========================================================
         * [DIRECT QUERY CHECK]
         * -----------------------------------------------------------
         * db.price_list.countDocuments({ batch: "M91" })
         * -- Expect: 0.
         * ===========================================================
         */
    }
}

  > 1. By a compound key
      1 price deleted
  > 2. Require exactly one
      caught ArxException: ARX2003 MultipleRecordsMatched: Delete of 'price_list': the entity matched several documents by columns (batch), but RequireSingleRow needs exactly one. Nothing was deleted.
  > 3. By any fields
      2 prices deleted