using System;
using System.Data.Common;
using System.Reflection;
using Npgsql.Logging;
namespace Npgsql
{
///
/// A factory to create instances of various Npgsql objects.
///
[Serializable]
public sealed class NpgsqlFactory : DbProviderFactory, IServiceProvider
{
static readonly NpgsqlLogger Log = NpgsqlLogManager.CreateLogger(nameof(NpgsqlFactory));
///
/// Gets an instance of the .
/// This can be used to retrieve strongly typed data objects.
///
public static readonly NpgsqlFactory Instance = new NpgsqlFactory();
NpgsqlFactory() {}
///
/// Returns a strongly typed instance.
///
public override DbCommand CreateCommand() => new NpgsqlCommand();
///
/// Returns a strongly typed instance.
///
public override DbConnection CreateConnection() => new NpgsqlConnection();
///
/// Returns a strongly typed instance.
///
public override DbParameter CreateParameter() => new NpgsqlParameter();
///
/// Returns a strongly typed instance.
///
public override DbConnectionStringBuilder CreateConnectionStringBuilder() => new NpgsqlConnectionStringBuilder();
///
/// Returns a strongly typed instance.
///
public override DbCommandBuilder CreateCommandBuilder() => new NpgsqlCommandBuilder();
///
/// Returns a strongly typed instance.
///
public override DbDataAdapter CreateDataAdapter() => new NpgsqlDataAdapter();
#if !NET461 && !NETSTANDARD2_0
///
/// Specifies whether the specific supports the class.
///
public override bool CanCreateDataAdapter => true;
///
/// Specifies whether the specific supports the class.
///
public override bool CanCreateCommandBuilder => true;
#endif
#region IServiceProvider Members
///
/// Gets the service object of the specified type.
///
/// An object that specifies the type of service object to get.
/// A service object of type serviceType, or null if there is no service object of type serviceType.
public object? GetService(Type serviceType)
{
if (serviceType == null)
throw new ArgumentNullException(nameof(serviceType));
// In legacy Entity Framework, this is the entry point for obtaining Npgsql's
// implementation of DbProviderServices. We use reflection for all types to
// avoid any dependencies on EF stuff in this project. EF6 (and of course EF Core) do not use this method.
if (serviceType.FullName != "System.Data.Common.DbProviderServices")
return null;
// User has requested a legacy EF DbProviderServices implementation. Check our cache first.
if (_legacyEntityFrameworkServices != null)
return _legacyEntityFrameworkServices;
// First time, attempt to find the EntityFramework5.Npgsql assembly and load the type via reflection
var assemblyName = typeof(NpgsqlFactory).GetTypeInfo().Assembly.GetName();
assemblyName.Name = "EntityFramework5.Npgsql";
Assembly npgsqlEfAssembly;
try {
npgsqlEfAssembly = Assembly.Load(new AssemblyName(assemblyName.FullName));
} catch (Exception e) {
Log.Debug("A service request was made for System.Data.Common.DbProviderServices, but the EntityFramework5.Npgsql assemby could not be loaded.", e);
return null;
}
Type? npgsqlServicesType;
if ((npgsqlServicesType = npgsqlEfAssembly.GetType("Npgsql.NpgsqlServices")) == null ||
npgsqlServicesType.GetProperty("Instance") == null)
throw new Exception("EntityFramework5.Npgsql assembly does not seem to contain the correct type!");
return _legacyEntityFrameworkServices = npgsqlServicesType
.GetProperty("Instance", BindingFlags.Public | BindingFlags.Static)!
.GetMethod!.Invoke(null, new object[0]);
}
static object? _legacyEntityFrameworkServices;
#endregion
}
}