public class OracleDbConnectionFactory : IDbConnectionFactory
{
    private readonly string _connectionString;

    public OracleDbConnectionFactory(string connectionString)
    {
        _connectionString = connectionString;
    }

    public DbConnection CreateConnection()
    {
        return new OracleConnection(_connectionString);
    }
}

using Dapper;
using Oracle.ManagedDataAccess.Client;
using StackExchange.Profiling.Internal;
using System;
using System.Data;
using System.Data.Common;
using System.Data.SqlClient;
using System.Diagnostics;
using System.Dynamic;
using System.Linq;
using System.Reflection;
using System.Transactions;

namespace NetFxConsole
{
    internal class Program
    {
        // TODO: encrypt the connection string and store it in the app.config
        private const string csOracle =
            "Data Source=(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=SqlDB)(PORT=1521))(CONNECT_DATA=(SERVICE_NAME=XEPDB1)));User Id=LAB;Password=****;";
        private const string csMsSql = "Data Source=SqlDB;Initial Catalog=LAB;User Id=LAB;Password=****;";

        static object GetSqlMapperParamReader(CommandDefinition cmd, IDbConnection cnn, object paramArg)
        {
            var sqlMapperType = typeof(SqlMapper);
            var sqlMapperIdentityType = sqlMapperType.Assembly.GetType("Dapper.SqlMapper+Identity");
            // TODO: hard-coded here, array index and parameters may differ in different versions of Dapper
            var identity = sqlMapperIdentityType.GetConstructors(
                BindingFlags.Instance | BindingFlags.NonPublic)[1].Invoke(new object[]
                {
                    cmd.CommandText, cmd.CommandType, string.Empty, typeof(string), paramArg.GetType(), null, 0
                });
            dynamic cacheInfo = sqlMapperType.GetMethod("GetCacheInfo", BindingFlags.Static | BindingFlags.NonPublic)
                .Invoke(null, new object[] { identity, paramArg, false });
            return cacheInfo.GetType().GetProperty("ParamReader").GetValue(cacheInfo, null);
        }

        public static void SimulateDapperDbParameters(string commandText, IDbConnection cnn, object paramArg)
        {
            var command = new CommandDefinition(commandText, paramArg);
            var paramReader = GetSqlMapperParamReader(command, cnn, paramArg);
            var mi = command.GetType().GetMethod("SetupCommand", BindingFlags.Instance | BindingFlags.NonPublic);
            var cmd = mi.Invoke(command, new object[] { cnn, paramReader });
            switch (cmd)
            {
                case OracleCommand oc:
                    Console.WriteLine($"CommandText: \x1b[33m{oc.CommandText}\x1b[0m");
                    foreach (OracleParameter p in oc.Parameters)
                    {
                        Console.WriteLine($" * \u001b[36m{p.ParameterName,-8}\u001b[0m / {p.DbType,-8} / \u001b[35m{$"{p.OracleDbType}({p.Size})",-16} \u001b[0m = {p.Value}");
                    }
                    break;
                case SqlCommand sc:
                    Console.WriteLine($"CommandText: \x1b[33m{sc.CommandText}\x1b[0m");
                    foreach (SqlParameter p in sc.Parameters)
                    {
                        Console.WriteLine($" * \u001b[36m{p.ParameterName,-8}\u001b[0m / {p.DbType,-8} / \u001b[35m{$"{p.SqlDbType}({p.Size})",-16}\u001b[0m = {p.Value}");
                    }
                    break;
                default:
                    throw new NotSupportedException();
            }
        }
        static void Main(string[] args)
        {
            var sql = "INSERT INTO SAMPLE VALUES (:name, :regDate, :score)";
            var paramObject = new
            {
                name = "Jeffrey",
                regDate = new DateTime(2012, 12, 21),
                score = 32767
            };
            using (var cn = new OracleConnection(csOracle))
            {
                SimulateDapperDbParameters(sql, cn, paramObject);
                FixOdpNetDbTypeStringMapping();
                SimulateDapperDbParameters(sql, cn, paramObject);
            }
            using (var cn = new SqlConnection(csMsSql))
            {
                sql = sql.Replace(":", "@");
                SimulateDapperDbParameters(sql, cn, paramObject);
            }
            Console.ReadLine();
        }
        // https://blog.darkthread.net/blog/dapper-odpnet-unicode-issue/
        static void FixOdpNetDbTypeStringMapping()
        {
            Assembly asm = typeof(OracleConnection).Assembly;
            Type tOraDb_DbTypeTable = asm.GetType("Oracle.ManagedDataAccess.Client.OraDb_DbTypeTable");
            var fldDbTypeMapping = tOraDb_DbTypeTable.GetField("dbTypeToOracleDbTypeMapping",
                BindingFlags.Static | BindingFlags.NonPublic);
            int[] mappings = (int[])fldDbTypeMapping.GetValue(null);
            mappings[(int)System.Data.DbType.String] = (int)OracleDbType.NVarchar2;
            fldDbTypeMapping.SetValue(null, mappings);
        }
    }
}