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.MongoDb;
using ArxSamples.MongoDb.Operations.Create.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 Basic3_CatchAnError().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.Create.Basics;

/// <summary>
/// The errors a create meets most, in three scenarios: a duplicate (a unique index), a value ARX refuses before
/// sending anything, and an id MongoDB can't make.
/// </summary>
/// <remarks>
/// Every error is an <see cref="ArxException"/> with a stable code. The message names the index, never the value
/// (MongoDB's own text quotes it). A plain insert never replaces a document.
/// </remarks>
public sealed class Basic3_CatchAnError : ISample
{
    public string Name => "create-basics-3-catch-an-error";

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

    public async Task RunAsync(SampleContext dbContext)
    {
        await Scenario1_ADuplicateAsync(dbContext.Service);

        await Scenario2_ADateThatMeansNotSetAsync(dbContext.Service);

        await Scenario3_AGeneratedNumberAsync(dbContext.ConnectionString);
    }

    /// <summary>1. A second account with the same number: ARX3001, with the index's name.</summary>
    private static async Task Scenario1_ADuplicateAsync(ArxMongoDbService service)
    {
        Step("1. A duplicate");

        var account = new ArxEntity("account");
        account["name"] = "Proseware, Inc.";
        account["account_number"] = "ACC-M301";
        await service.CreateAsync(account);

        var again = new ArxEntity("account");
        again["name"] = "Proseware copy";
        again["account_number"] = "ACC-M301";

        try
        {
            await service.CreateAsync(again);
        }
        catch (ArxDatabaseException exception) when (exception.Code == ArxErrorCode.UniqueViolation)
        {
            ShowError(exception);
            Show($"index {exception.ConstraintName}, MongoDB error {exception.NativeCode}");
        }

        /* ===========================================================
         * [DIRECT QUERY CHECK]
         * -----------------------------------------------------------
         * db.account.countDocuments({ account_number: "ACC-M301" })
         * -- Expect: 1.
         * ===========================================================
         */
    }

    /// <summary>2. default(DateTime) means "not set": ARX1013 before anything is sent.</summary>
    private static async Task Scenario2_ADateThatMeansNotSetAsync(ArxMongoDbService service)
    {
        Step("2. A date that means \"not set\"");

        var account = new ArxEntity("account");
        account["account_number"] = "ACC-M302";
        account["created_on"] = default(DateTime);

        try
        {
            await service.CreateAsync(account);
        }
        catch (ArxValidationException exception) when (exception.Code == ArxErrorCode.InvalidDateTimeValue)
        {
            ShowError(exception);
        }

        /* ===========================================================
         * [DIRECT QUERY CHECK]
         * -----------------------------------------------------------
         * db.account.find({ account_number: "ACC-M302" })
         * -- Expect: no documents.
         * ===========================================================
         */
    }

    /// <summary>3. A generated number id: MongoDB has no sequences, so ARX8001; use an ObjectId or a Guid.</summary>
    private static async Task Scenario3_AGeneratedNumberAsync(string connectionString)
    {
        Step("3. A generated number id");

        var schema = ArxSchemaCatalog.Create()
            .Table("activity_log", ArxIdColumn.Generated<long>("log_id"))
            .Build();

        var service = new ArxMongoDbService(connectionString, schema);

        var entry = new ArxEntity("activity_log");
        entry["action"] = "signed in";

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

        /* ===========================================================
         * [DIRECT QUERY CHECK]
         * -----------------------------------------------------------
         * db.activity_log.find({ action: "signed in" })
         * -- Expect: no documents.
         * ===========================================================
         */
    }
}

  > 1. A duplicate
      caught ArxDatabaseException: ARX3001 UniqueViolation: Create on 'account': a record with the same value in unique index 'account_number_1' already exists.
      index account_number_1, MongoDB error 11000
  > 2. A date that means "not set"
      caught ArxValidationException: ARX1013 InvalidDateTimeValue: Attribute 'created_on' on 'account' is default(DateTime) (DateTime.MinValue), which means "not set". Set a real value or null.
  > 3. A generated number id
      caught ArxNotSupportedException: ARX8001 NotSupported: Table 'activity_log' declares id 'log_id' as a generated Int64. MongoDB has no sequences: ARX makes ObjectId (ArxIdColumn.Generated<string>) and Guid (ArxIdColumn.Generated<Guid>) ids, or give the id yourself and declare it ArxIdColumn.Supplied<Int64>.