Oracle sequence EF Core 6.0? - oracle

Question

I need to get a NEXTVAL from a SEQUENCE in an Oracle database. The modelbuilder does have a
builder.HasSequence("TABLE_SEQ");
But I have no clue on how to use that. The only way I can think of is scalar executing a raw SQL to retrieve the next value. Is that the way to go or are there better ways to do this?
I've found several posts that say I should use context.Database.SqlQuery() but in my solution that is missing. Do I need to add a library to get this functionality for EF 6.0?
Examples I found:
Example 1:
public int GetNewCertificateTradeRequestIdentity()
{
using var command = _context.Database.GetDbConnection().CreateCommand();
command.CommandText = "SELECT ts.seq_certificate_trade_request.NEXTVAL FROM DUAL";
_context.Database.OpenConnection();
using var reader = command.ExecuteReader();
reader.Read();
return reader.GetInt32(0);
}
Example 2:
users = await context.Database.SqlQuery<User>("Select * from User", new object[] { }).ToListAsync();
Both the _context.Database.GetDbConnection() context.Database.SqlQuery<x> are missing. Where can I find them?

Answer 1

Ok, in EF6 you have the context.Database.GetDbConnection().CreateCommand(). With that command you can execute a query on the database and receive the result. I've also found a solution for getting the tablename from the EF6 Metadata and added an extension method to handle that. Now I can do the the following:
private Tijdverantwoording Create(decimal? mdwid, decimal? deelprjid, Datum? date)
{
if (mdwid == null || deelprjid == null || date == null) throw new ArgumentNullException();
Weekstaatstatus weekstaatStatus = _WeekstaatStatusService.GetOrCreate(mdwid.Value, date.Jaarweekcode, WeekStaatStatussen.InBewerking, DateTime.Now);
var tijdverantwoording = new Tijdverantwoording
{
Tijdverantwoordingid = GetId<Tijdverantwoording>(), // <= Generate id
Mdwid = mdwid.Value,
Deelprjid = deelprjid.Value,
Datum = date.DagDatum,
Syncstatus = (decimal)SyncStatuses.InBewerking,
Syncdate = DateTime.Now.Date,
Weekstaatstatusid = weekstaatStatus.Weekstaatstatusid
};
_modelContext.Tijdverantwoordingen.Add(tijdverantwoording);
return tijdverantwoording;
}
The base class used for a service.
using Microsoft.EntityFrameworkCore;
using MyProjects.Core.Extensions;
using MyProjects.Core.Model;
namespace MyProjects.Core.Services
{
public class ServiceBase
{
private ModelContext? _modelContext;
public ServiceBase(ModelContext modelContext)
{
_modelContext = modelContext;
}
public decimal GetId<T>()
where T : class
{
var command = _modelContext.Database.GetDbConnection().CreateCommand();
var tableName = _modelContext.TableName(typeof(T));
command.CommandType = System.Data.CommandType.Text;
command.CommandText = $"SELECT {tableName}_SEQ.NEXTVAL FROM DUAL";
_modelContext.Database.OpenConnection();
try
{
var result = (decimal?)command.ExecuteScalar();
return result.Value;
}
finally
{
_modelContext.Database.CloseConnection();
}
}
}
}
And the extension method
using Microsoft.EntityFrameworkCore;
namespace MyProjects.Core.Extensions
{
public static class DatabaseExtensions
{
public static string? TableName(this DbContext context, Type type)
{
var entityType = context.Model.FindEntityType(type);
return entityType?.GetTableName() ?? throw new NullReferenceException($"Can't find name for type {type.Name}");
}
}
}