2chBackAPI/DBControllers/DBchat.cs

using NeDvachAPI.Models;
using Npgsql;

namespace NeDvachAPI.DBControllers
{
    public class DBchat
    {
        public static List<Post> PostsList(string boardName, int thread)
        {
            List<Post> posts = new List<Post>();
            string connString =
                string.Format(
                    "Server={0}; User Id={1}; Database={2}; Port={3}; Password={4};SSLMode=Prefer",
                    AuthInfo.DB.Host,
                    AuthInfo.DB.User,
                    AuthInfo.DB.DBname,
                    AuthInfo.DB.Port,
                    AuthInfo.DB.Password);

            using (var conn = new NpgsqlConnection(connString))
            {


                conn.Open();
                using (var command = new NpgsqlCommand($@"
                SELECT * FROM 
                (
                    SELECT post_id, post_text, content, post_timestamp
                    FROM posts
                    WHERE thread_id = {thread}
                    ORDER BY post_id DESC 
                ) subquery
                ORDER BY post_id ASC", conn))
                {

                    var reader = command.ExecuteReader();
                    while (reader.Read())
                    {
                        Post receivedPost = new()
                        {
                            Id = reader.GetInt32(0),
                            Text = reader.GetString(1),
                            ImgURL = reader.IsDBNull(2) ? null : reader.GetFieldValue<string[]>(2),
                            Timestamp = reader.GetString(3)

                        };
                        posts.Add(receivedPost);
                    }
                    reader.Close();
                }
            }
            return posts;
        }

        public static List<Post> ThreadsList(string boardName)
        {
            List<Post> posts = new List<Post>();
            string received = "";
            string connString =
                string.Format(
                    "Server={0}; User Id={1}; Database={2}; Port={3}; Password={4};SSLMode=Prefer",
                    AuthInfo.DB.Host,
                    AuthInfo.DB.User,
                    AuthInfo.DB.DBname,
                    AuthInfo.DB.Port,
                    AuthInfo.DB.Password);

            using (var conn = new NpgsqlConnection(connString))
            {


                conn.Open();

                using (var command = new NpgsqlCommand($@"
                SELECT * FROM 
                (
                    SELECT post_id, post_text, content, post_timestamp, is_op, thread_id
                    FROM posts
                    WHERE
                    is_op = {true}
                    ORDER BY post_id DESC 
                ) subquery
                ORDER BY post_id ASC", conn))
                {

                    var reader = command.ExecuteReader();
                    while (reader.Read())
                    {
                        Post receivedPost = new()
                        {
                            Id = reader.GetInt32(0),
                            Text = reader.GetString(1),
                            ImgURL = reader.IsDBNull(2) ? null : reader.GetFieldValue<string[]>(2),
                            Timestamp = reader.GetString(3),
                            Is_OP = reader.GetBoolean(4),
                            Thread_Id = reader.GetInt32(5)

                        };
                        posts.Add(receivedPost);
                    }
                    reader.Close();
                }
            }
            return posts;
        }

        public static void DbUpdate(string id, string text)
        {
            string connString =
                string.Format(
                    "Server={0}; User Id={1}; Database={2}; Port={3}; Password={4};SSLMode=Prefer",
                    AuthInfo.DB.Host,
                    AuthInfo.DB.User,
                    AuthInfo.DB.DBname,
                    AuthInfo.DB.Port,
                    AuthInfo.DB.Password);

            using (var conn = new NpgsqlConnection(connString))
            {
                conn.Open();

                using (var command = new NpgsqlCommand("UPDATE dvach " +
                    "SET post = @postText WHERE post_id = @ID", conn))
                {
                    command.Parameters.AddWithValue("ID", int.Parse(id));
                    command.Parameters.AddWithValue("postText", text);

                    int nRows = command.ExecuteNonQuery();
                    Console.Out.WriteLine(string.Format("Number of rows updated={0}", nRows));
                }
            }

            Console.WriteLine("Данные обновлены!");
            Console.ReadLine();
        }
        public static void SendPost(Post postToSend)   //sending post to database
        {
            string connString =
                string.Format(
                    "Server={0}; User Id={1}; Database={2}; Port={3}; Password={4};SSLMode=Prefer",
                    AuthInfo.DB.Host,
                    AuthInfo.DB.User,
                    AuthInfo.DB.DBname,
                    AuthInfo.DB.Port,
                    AuthInfo.DB.Password);

            using (var conn = new NpgsqlConnection(connString))
            {

                Console.Out.WriteLine("Opening connection");
                conn.Open();
                int postNum = 14;

                using (var command = new NpgsqlCommand(@"
                INSERT INTO posts (post_id, post_text, post_number, content, thread_id, auth_ip, is_op, post_timestamp) 
                VALUES ( 
                        DEFAULT, 
                        @postText,
                        @postNum,
                        @postImgUrl,
                        @threadId,
                        @ip,
                        false,
                (
                    SELECT date_trunc(
                        'second',
                        (now()::timestamp(0) AT TIME ZONE 'UTC+10')::TIMESTAMP
                    )
                ) )", conn))
                {
                    command.Parameters.AddWithValue("postText", postToSend.Text);
                    command.Parameters.AddWithValue("postNum", postNum);
                    command.Parameters.AddWithValue("postImgUrl", postToSend.ImgURL);
                    command.Parameters.AddWithValue("threadId", postToSend.Thread_Id);
                    command.Parameters.AddWithValue("ip", postToSend.Ip);
                    int nRows = command.ExecuteNonQuery();
                    Console.Out.WriteLine("Добавлен пост с текстом " + postToSend.Text + " номером " + 22);
                }
            }

        }
        public static void DeletePost(string idToDel) //удалялка
        {
            string connString =
                string.Format(
                    "Server={0}; User Id={1}; Database={2}; Port={3}; Password={4};SSLMode=Prefer",
                    AuthInfo.DB.Host,
                    AuthInfo.DB.User,
                    AuthInfo.DB.DBname,
                    AuthInfo.DB.Port,
                    AuthInfo.DB.Password);

            using (var conn = new NpgsqlConnection(connString))
            {

                conn.Open();

                using (var command = new NpgsqlCommand(@"
                DELETE FROM dvach 
                WHERE post_id = @ID", conn))
                {
                    command.Parameters.AddWithValue("ID", int.Parse(idToDel)); ;

                    int nRows = command.ExecuteNonQuery();
                    Console.Out.WriteLine(string.Format("Number of rows updated={0}", nRows));
                }
            }

            Console.WriteLine("Данные удалены!");
            Console.ReadLine();

        }
    }
}