Beauty_Salon/BeautySalon/BeautySalonDBModels/Implements/MasterDatabase.cs

using BeautySalonDBModels.Models;
using Npgsql;
using System;
using System.Collections.Generic;
using System.Diagnostics.Metrics;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace BeautySalonDBModels.Implements
{
    public class MasterDatabase : AbstractWorkWithStorage<Master>
    {
        public override void Add(Master master)
        {
            using var conn = GetConnection();
            conn.Open();
            using var cmd = new NpgsqlCommand("INSERT INTO masters (master_id, specialisation_id, fio) VALUES ((nextval('seq_master'), @SpecialisationId, @FIO)", conn);
            cmd.Parameters.AddWithValue("@SpecialisationId", master.SpecialisationId);
            cmd.Parameters.AddWithValue("@FIO", master.FIO);
            cmd.ExecuteNonQuery();
        }

        public override Master? GetObject(int id)
        {
            using var conn = GetConnection();
            conn.Open();
            using var cmd = new NpgsqlCommand("SELECT * FROM masters WHERE master_id = @id", conn);
            cmd.Parameters.AddWithValue("@id", id);
            using var reader = cmd.ExecuteReader();
            if (reader.Read())
            {
                return new Master
                {
                    MasterId = reader.GetInt32(0),
                    SpecialisationId = reader.GetInt32(1),
                    FIO = reader.GetString(2)
                };
            }
            return null;
        }

        public override List<Master> GetObjects()
        {
            var masters = new List<Master>();
            using var conn = GetConnection();
            conn.Open();
            using var cmd = new NpgsqlCommand("SELECT * FROM masters order by master_id", conn);
            using var reader = cmd.ExecuteReader();
            while (reader.Read())
            {
                masters.Add(new Master
                {
                    MasterId = reader.GetInt32(0),
                    SpecialisationId = reader.GetInt32(1),
                    FIO = reader.GetString(2)
                });
            }
            return masters;
        }

        public override Master? Remove(int id)
        {
            var master = GetObject(id);
            using var conn = GetConnection();
            conn.Open();
            using var cmd = new NpgsqlCommand("delete from masters where master_id = @id", conn);

            cmd.Parameters.AddWithValue("@id", id);
            cmd.ExecuteNonQuery();
            return master;
        }

        public override void Update(Master master)
        {
            using var conn = GetConnection();
            conn.Open();
            using var cmd = new NpgsqlCommand("update master set specialisation_id = @specId, " +
                "fio = @fio where master_id = @id", conn);
            cmd.Parameters.AddWithValue("@specId", master.SpecialisationId);
            cmd.Parameters.AddWithValue("@fio", master.FIO);
            cmd.Parameters.AddWithValue("@id", master.MasterId);
            cmd.ExecuteNonQuery();
        }
    }
}