Ability to use LinqToDb with the non-default collection about helpful-libraries

[Piedone]

Can you explain what would you like to achieve, with an example?

[intellimedhu]

For some reason, it's essential to store specific data (called BigData below) isolated from the Document table. However, it would be nice to write LINQ queries that access tables prefixed with the collection name.

public class BigData
{
    public int SomeNumber { get; set; }

    public string SomeValue { get; set; }
}

public class BigDataIndex : MapIndex
{
    public int SomeNumber { get; set; }

    public string SomeValue { get; set; }
}

public class BigDataIndexProvider : IndexProvider<BigData>
{
    public BigDataIndexProvider()
    {
        CollectionName = BigDataService.CollectionName;
    }

    public override void Describe(DescribeContext<BigData> context)
        => context.For<BigDataIndex>()
            .Map(x => new()
            {
                SomeNumber = x.SomeNumber,
                SomeValue = x.SomeValue
            });
}

public class BigDataMigration : DataMigration
{
    public int Create()
    {
        SchemaBuilder.CreateMapIndexTable<BigDataIndex>(table => table
            .Column<int>(nameof(BigDataIndex.SomeNumber))
            .Column<string>(nameof(BigDataIndex.SomeValue)),
            collection: BigDataService.CollectionName
        );

        SchemaBuilder.AlterIndexTable<BigDataIndex>(table =>
        {
            table.CreateIndex("IDX_SBD_NUM", nameof(BigDataIndex.SomeNumber));
            table.CreateIndex("IDX_SBD_VAL", nameof(BigDataIndex.SomeValue));
        },
        collection: BigDataService.CollectionName);

        return 1;
    }
}

public class BigDataService
{
    private readonly ISession _session;

    public const string CollectionName = "BIG_DATA";

    public BigDataService(ISession session)
    {
        _session = session;
    }

   
    public async Task<IEnumerable<BigDataIndex>> GetDataAsync()
    {
        // This method throws ex: no such table: BigDataIndex
        return await _session
            .LinqQueryAsync(accessor => accessor
                .GetTable<BigDataIndex>()
                .ToListAsync());
    }
}

public class BigDataController : Controller
{
    private readonly BigDataService _bigDataService;

    public BigDataController(BigDataService bigDataService)
    {
        _bigDataService = bigDataService;
    }

    public async Task<IActionResult> GetData()
    {
        var data = await _bigDataService.GetDataAsync();

        return Ok(data);
    }
}

public class Startup : StartupBase
{
    public override void ConfigureServices(IServiceCollection services)
    {
        services.Configure<StoreCollectionOptions>(x => x.Collections.Add(BigDataService.CollectionName));
        services.AddSingleton<IIndexProvider, BigDataIndexProvider>();
        services.AddScoped<IDataMigration, BigDataMigration>();
        services.AddScoped<BigDataService>();
    }
}

[Piedone]

I see, so basically the issue is that the methods in LinqToDbQueryExecutor expect the table name to be the same as the class name, but your is BIG_DATA_BigDataIndex, right?

We could fix this by adding a GetTable(string tableName) to ITableAccessor for the generic case, maybe a GetTable<T>(string collectionName) shortcut as well.

[intellimedhu]

That's right. Thank you!

[Piedone]

Great then!

Looking at the types I mentioned, would you consider a contribution for this?

[intellimedhu]

Yes (with another github account)

[Piedone]

Thank you!