Remove the contacts a user selected

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

using ArxSamples.MSSQL;
using ArxSamples.MSSQL.Operations.DeleteMultiple.RealCases;

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

await new RealCase1_RemoveSelectedContacts().RunAsync(new SampleContext(connectionString));

The sample, as it is in the repository.

using ARX.SDK.Services;

using static ArxSamples.MSSQL.SampleOutput;

namespace ArxSamples.MSSQL.Operations.DeleteMultiple.RealCases;

/// <summary>
/// Removing the contacts a user ticked, in two scenarios: a list screen that has their ids, and an unsubscribe file
/// that has only email addresses (the contact table's declared key).
/// </summary>
/// <remarks>
/// <para>Both are one call, all or nothing: either every matching contact goes or, when the database refuses one (a
/// reference to it, for example), none does.</para>
/// </remarks>
public sealed class RealCase1_RemoveSelectedContacts : ISample
{
    public string Name => "delete-multiple-real-1-remove-selected-contacts";

    public string Title => "Remove the contacts a user selected";

    public async Task RunAsync(SampleContext dbContext)
    {
        var contacts = new List<ArxEntity>();
        foreach (var (first, last) in new[] { ("Ines", "Moreau"), ("Kenji", "Sato"), ("Lena", "Fischer"), ("Marco", "Bianchi"), ("Nadia", "Rahman") })
        {
            var contact = new ArxEntity("contact");
            contact["first_name"] = first;
            contact["last_name"] = last;
            contact["email"] = $"{first.ToLowerInvariant()}.{last.ToLowerInvariant()}@example.com";
            contacts.Add(contact);
        }

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

        await Scenario1_TheTickedRowsOfAListAsync(dbContext, new[] { ids[0], ids[1], ids[2] });

        await Scenario2_AnUnsubscribeFileOfEmailsAsync(dbContext);
    }

    /// <summary>1. The list screen sends the ids of the rows the user ticked.</summary>
    private static async Task Scenario1_TheTickedRowsOfAListAsync(SampleContext dbContext, IReadOnlyList<ArxRecordId> selected)
    {
        Step("1. The ticked rows of a list");

        int deleted = await dbContext.Service.DeleteMultipleAsync("contact", selected);

        Show($"{deleted} of {selected.Count} selected contacts removed");

        /* ===========================================================
         * [DIRECT QUERY CHECK]
         * -----------------------------------------------------------
         * SELECT count(*)
         * FROM contact
         * WHERE email IN ('ines.moreau@example.com', 'kenji.sato@example.com', 'lena.fischer@example.com');
         * -- Expect: 0.
         * ===========================================================
         */
    }

    /// <summary>2. An unsubscribe file has only emails: one entity per address, found by the declared key.</summary>
    private static async Task Scenario2_AnUnsubscribeFileOfEmailsAsync(SampleContext dbContext)
    {
        Step("2. An unsubscribe file of emails");

        var file = new[] { "marco.bianchi@example.com", "nadia.rahman@example.com", "nobody@example.com" };

        var requests = file.Select(email =>
        {
            var request = new ArxEntity("contact");
            request["email"] = email;
            return request;
        }).ToList();

        // An address with no contact isn't an error: the count says how many were really there.
        int deleted = await dbContext.Service.DeleteMultipleAsync(requests, new ArxDeleteOptions { Match = ArxMatch.Key("email") });

        Show($"{deleted} of {file.Length} addresses removed");

        /* ===========================================================
         * [DIRECT QUERY CHECK]
         * -----------------------------------------------------------
         * SELECT count(*)
         * FROM contact
         * WHERE email IN ('marco.bianchi@example.com', 'nadia.rahman@example.com');
         * -- Expect: 0.
         * ===========================================================
         */
    }
}

  > 1. The ticked rows of a list
      3 of 3 selected contacts removed
  > 2. An unsubscribe file of emails
      2 of 3 addresses removed