Develop Reference

Discord.net task call issue

I'm trying to create a discord bot in .NET with a command to put a user on markers. For example, a server admin gives a user 50 markers and the user would get all of his roles removed and would be given a role called "Markers". Then, a text channel will appear where the user needs to spam 50 messages to remove the markers and he'd get everything back. I have made commands for giving markers and removing them but when I try to remove someone's markers by calling the function from the Program.cs it gives a null pointer exception for some reason. Here's the code:
Program.cs event:
private async Task MessageRecieved(SocketMessage arg)
{
//Checking if the user has markers
var roles = (arg.Author as SocketGuildUser).Roles;
bool imaMarkere = false;
foreach (var role in roles)
{
if (role.Id == 844558286611152917)
imaMarkere = true;
}
if (arg.Channel.Id == 844558185024585770 && imaMarkere)
{
int markerCount = 0;
using (SqliteConnection con = new SqliteConnection(connectionString))
{
con.Open();
string query = $"select markercount from markers";
var com = con.CreateCommand();
com.CommandText = query;
var rdr = com.ExecuteReader();
if (rdr.Read())
{
markerCount += Convert.ToInt32(rdr["markercount"]) - 1;
}
rdr.Close();
//Removing 1 marker per message recieved
if (markerCount > 0)
{
com.CommandText = $"update markers set markercount={markerCount} where userid='{arg.Author.Id}'";
com.ExecuteNonQuery();
}
//If no markers are left returning the user roles
else
{
Commands c = new Commands();
await c.Skini(arg.Author as IGuildUser);
}
con.Close();
}
}
else return;
}
Commands.cs
[Command("skini"), RequireUserPermission(GuildPermission.Administrator, ErrorMessage = "Nemate potrebnu dozvolu ``ADMINISTRATOR``")]
public async Task Skini(IGuildUser user = null)
{
if(user == null)
{
await ReplyAsync($"{Context.User.Mention},kome da skinem?");
}
string rolesString = "";
string[] roles;
using (SqliteConnection con = new SqliteConnection(connectionString))
{
con.Open();
var com = con.CreateCommand();
string readQuery = "select pastroles from markers";
com.CommandText = readQuery;
var rdr = com.ExecuteReader();
if (rdr.Read())
{
rolesString += rdr["pastroles"].ToString();
}
rdr.Close();
string deleteQuery = $"delete from markers where userid = '{user.Id}'";
com.CommandText = deleteQuery;
com.ExecuteNonQuery();
con.Close();
}
roles = rolesString.Split(",");
foreach (var roleid in roles)
{
var role = Context.Guild.GetRole(Convert.ToUInt64(roleid));//this line is where the exception happens
if(!role.IsEveryone)
await user.AddRoleAsync(role);
}
var roleMarkeri = Context.Guild.GetRole(844558286611152917);
await user.RemoveRoleAsync(roleMarkeri);
var EmbedBuilder = new EmbedBuilder()
.WithTitle("**MARKERI**")
.WithColor(Color.Blue)
.WithDescription($":white_check_mark: {Context.User.Mention} je **skinuo** markere {user.Username}")
.WithFooter(footer =>
{
footer
.WithText("Marker log");
});
Embed embed = EmbedBuilder.Build();
await ReplyAsync(embed: embed);
}

Retrieve multiple rows from SQL Server in a web service and xamarin android?

I want to retrieve multiple rows from SQL Server in a web service. I get 2 rows as result when I search jo number 1 and my table name is TestOrderStatus.
While I get only one row in the search result.
Thanks for all
public class ReturnOrder
{
public string Message;
public int QtqSlit;
public int QtyPcs;
public string Design;
}
[WebMethod(MessageName = "OrderStatus", Description = "OrderStatus new Order")]
[System.Xml.Serialization.XmlInclude(typeof(ReturnOrder))]
public ReturnOrder OrderStatus(string JO) /// get list of notes
{
int QtqSlit = 0;
int QtyPcs = 0;
String Design = "";
string Message = "";
SqlDataReader reader;
using (SqlConnection connection = new SqlConnection(DBConnection.ConnectionString))
{
SqlCommand cmd = new SqlCommand("SELECT QtqSlit,QtyPcs,Design FROM TestOrderStatus where JO=#JO");
cmd.CommandType = CommandType.Text;
cmd.Connection = connection;
cmd.Parameters.AddWithValue("#JO", JO);
connection.Open();
reader = cmd.ExecuteReader();
while (reader.Read())
{
for (int i = 0; i < reader.FieldCount; i++)
{
QtqSlit = reader.GetInt32(0);
QtyPcs = reader.GetInt32(1);
Design = reader.GetString(2);
}
}
if (QtqSlit == 0)
{
Message = " user name or password is incorrect";
}
reader.Close();
connection.Close();
}
ReturnOrder rt = new ReturnOrder();
rt.Message = Message;
rt.QtqSlit = QtqSlit;
rt.QtyPcs = QtyPcs;
rt.Design = Design;
return rt;
}

You need a List for multiple rows if you want more than one result. So your code may be like this.
public class ReturnOrder
{
public string Message;
public int QtqSlit;
public int QtyPcs;
public string Design;
}
[WebMethod(MessageName = "OrderStatus", Description = "OrderStatus new Order")]
[System.Xml.Serialization.XmlInclude(typeof(List<ReturnOrder>))]
public List<ReturnOrder> OrderStatus(string JO) /// get list of notes
{
List<ReturnOrder> result=new List<ReturnOrder>();
int QtqSlit = 0;
int QtyPcs = 0;
String Design = "";
string Message = "";
//try
//{
SqlDataReader reader;
using (SqlConnection connection = new SqlConnection(DBConnection.ConnectionString))
{
SqlCommand cmd = new SqlCommand("SELECT QtqSlit,QtyPcs,Design FROM TestOrderStatus where JO=#JO");
cmd.CommandType = CommandType.Text;
cmd.Connection = connection;
cmd.Parameters.AddWithValue("#JO", JO);
connection.Open();
reader = cmd.ExecuteReader();
while (reader.Read())
{
QtqSlit = reader.GetInt32(0);
QtyPcs = reader.GetInt32(1);
Design = reader.GetString(2);
ReturnOrder rt = new ReturnOrder();
rt.Message = Message;
rt.QtqSlit = QtqSlit;
rt.QtyPcs = QtyPcs;
rt.Design = Design;
result.add(rt);
}
if (QtqSlit == 0)
{
Message = " user name or password is in correct";
}
reader.Close();
connection.Close();
}
//}
//catch (Exception ex)
//{
// Message = " cannot access to the data";
//}
return result;
}

Thank you to much now web service is ok , But when he summoned the values in Xamrian Android doesn't know.
public class Mainlistview : Activity
{
protected override void OnCreate(Bundle bundle)
{
base.OnCreate(bundle);
// Set our view from the "main" layout resource
SetContentView(Resource.Layout.Mainlistview);
ListView ListView = FindViewById<ListView>(Resource.Id.listView1);
Selling.WebServiceDB ws = new Selling.WebServiceDB();
ws.OrderStatusListCompleted += Ws_OrderStatusListCompleted;
ws.OrderStatusListAsync(Convert.ToString(1));
}
private void Ws_OrderStatusListCompleted(object sender, Selling.OrderStatusListCompletedEventArgs e)
{
ListView ListView = FindViewById<ListView>(Resource.Id.listView1);
string msg = "";
if (e.Result.QtqSlit.ToString().Equals("0"))
{
msg = e.Result.Message;
}
else
{
// full class
List<TableItem> tableItems = new List<TableItem>();
tableItems.Add(new TableItem("" + e.Result.QtqSlit, "" + e.Result.QtyPcs, Resource.Drawable.Icon));
ListView.Adapter = new HomeScreenAdapter(this, tableItems);
}
}

SignalR Content dont update if send to Client.Caller

Hello and thanks for reading this.
This is my NotificationHub.cs
public class NotificationHub : Hub
{
private static readonly ConcurrentDictionary<string, User> Users = new ConcurrentDictionary<string, User>(StringComparer.InvariantCultureIgnoreCase);
private static List<User> UserList = new List<User>();
Int16 totalNewMessages = 0;
string UserID;
[HubMethodName("check")]
public Task Check(string id)
{
string profileId = id; //Context.QueryString["id"];
string connectionId = Context.ConnectionId;
var user = Users.GetOrAdd(profileId, _ => new User
{
ProfileId = profileId,
ConnectionIds = id
});
lock (user.ConnectionIds)
{
Groups.Add(connectionId, user.ProfileId);
}
return base.OnConnected();
}
[HubMethodName("sendNotifications")]
public Task SendNotifications(string id)
{
UserID = id;
using (var connection = new SqlConnection(ConfigurationManager.ConnectionStrings["DefaultConnection"].ConnectionString))
{
string query = "SELECT NotificationNumber FROM [dbo].[NotificationStatus] WHERE UserID=" + UserID;
connection.Open();
using (SqlCommand command = new SqlCommand(query, connection))
{
command.Notification = null;
DataTable dt = new DataTable();
SqlDependency dependency = new SqlDependency(command);
dependency.OnChange += new OnChangeEventHandler(dependency_OnChange);
if (connection.State == ConnectionState.Closed)
connection.Open();
var reader = command.ExecuteReader();
dt.Load(reader);
if (dt.Rows.Count > 0)
{
totalNewMessages = Int16.Parse(dt.Rows[0]["NotificationNumber"].ToString());
}
}
}
User CurrentUser = UserList.FirstOrDefault(i => i.ProfileId == UserID);
IHubContext context = GlobalHost.ConnectionManager.GetHubContext<NotificationHub>();
//return context.Clients.All.RecieveNotification(totalNewMessages);
return context.Clients.Client(Users.Values.FirstOrDefault(i => i.ProfileId == UserID).ConnectionIds).RecieveNotification(totalNewMessages);
}
private void dependency_OnChange(object sender, SqlNotificationEventArgs e)
{
if (e.Type == SqlNotificationType.Change)
{
NotificationHub nHub = new NotificationHub();
nHub.SendNotifications(UserID);
}
}
}
These 2 lines is what I want to focus on.
//return context.Clients.All.RecieveNotification(totalNewMessages);
return context.Clients.Client(Users.Values.FirstOrDefault(i => i.ProfileId == UserID).ConnectionIds).RecieveNotification(totalNewMessages);
If i use the first line it returns the totalNewMessages back to ALL people on the website, but i only want to to return back to the user that requested it.
The second line is my attempt to return the totalNewMessages back tot he specific user, but it dont work.
How can i return the totalNewMessages Back to only the specific user?

I came across this problem a while back. I got it working by returning the messages depending on the user who's logged in
string userName = HttpContext.Current.User.Identity.Name;
return context.Clients.User(userName).RecieveNotification(totalNewMessages);
Also look into parameterized queries to prevent sql injection. There's a handy documentation for what you're trying to achieve here

How to automatically update database value when issue book in library management

I want to make a library system in C#. In this system when a book is issued it should automatically reduce the book quantity in database. When book quantity == 0 there should be a message box showing "not available".
This is my code:
private void btnIssue_Click(object sender, EventArgs e)
{
if (cmbResID.Text != "" && cmbMemID.Text != "" && cmbBookID.Text != "" && txtBkTitle.Text != "" && txtCategory.Text != "" && txtAuthor.Text != "" && txtIssueDate.Text != "" && txtActDate.Text != "")
{
SqlCommand Quantity = new SqlCommand("Select * from tblBookDetails where Book_ID = '" + cmbBookID.Text +"'");
DataSet ds = Library.Select(Quantity);
if (ds.Tables[0].Rows.Count > 0)
{
textBox1.Text = ds.Tables[0].Rows[0].ItemArray.GetValue(5).ToString();
int b = Convert.ToInt32(textBox1.Text);
if (b > 0)
{
//a = a - 1;
//int b = Convert.ToInt32(a);
//label15.Text = a.ToString();
SqlCommand update=new SqlCommand("UPDATE tblBookDetails SET Quantity=Quantity-1 WHERE Book_ID='"+ cmbBookID +"'");
Library.ExecuteInsert(update);
SqlCommand save = new SqlCommand("insert into tblBookIssue values(#ResID,#Member_ID,#Book_ID,#Issue_Date,#Act_Ret_Date)");
save.Parameters.AddWithValue("#ResID", cmbResID.Text);
save.Parameters.AddWithValue("#Member_ID", cmbMemID.Text);
save.Parameters.AddWithValue("#Book_ID", cmbBookID.Text);
save.Parameters.AddWithValue("#Issue_Date", txtIssueDate.Text);
save.Parameters.AddWithValue("#Act_Ret_Date", txtActDate.Text);
Library.Insert(save);
MessageBox.Show("Book Issued", "Book Issue", MessageBoxButtons.OK, MessageBoxIcon.Information);
clear();
}
else
{
MessageBox.Show("this book is not available");
}
}
}
else
{
MessageBox.Show("FILL COLUMS");
}
}

Executing SQL based off of text boxes is very unsafe and Prone to SQL injection attacks. Also, to follow Object Oriented program and make much cleaner code it would be advisable to make a Book object, I completed some code below which shows an example including the book incrementer. It would be better to make focused stored procs which execute gets for books and updates for book checkouts. You will have to turn your basic select into a stored proc, and write another proc which looks at the quantity and if quantity < 1 return 0 else return 1. Let me know if you need more info, this code should help you get rolling
using System;
using System.Data;
using System.Data.SqlClient;
namespace MockLibrary
{
internal class Book
{
#region Constructors
public Book()
{
}
public Book(string resId, string memberId, string bookId, DateTime issueDate, DateTime actRetDate)
{
this.ResId = resId;
this.MemberId = memberId;
this.BookId = bookId;
this.IssueDate = issueDate;
this.ActRetDate = actRetDate;
}
#endregion
#region Properties
private string _ResID;
private string _MemberID;
private string _BookId;
private DateTime _IssueDate;
private DateTime _ActRetDate;
public string ResId
{
get { return _ResID; }
set { _ResID = value; }
}
public string MemberId
{
get { return _MemberID; }
set { _MemberID = value; }
}
public string BookId
{
get { return _BookId; }
set { _BookId = value; }
}
public DateTime IssueDate
{
get { return _IssueDate; }
set { _IssueDate = value; }
}
public DateTime ActRetDate
{
get { return _ActRetDate; }
set { _ActRetDate = value; }
}
#endregion
public Book GetBookByID(string resId, string memberId)
{
try
{
using (SqlConnection con = new SqlConnection("put your db con string here"))
{
using (SqlCommand cmd = new SqlCommand("sp_GetBookById", con))
{
cmd.CommandType = CommandType.StoredProcedure;
cmd.Parameters.Add("#ResId", SqlDbType.VarChar).Value = resId;
cmd.Parameters.Add("#MemberId", SqlDbType.VarChar).Value = memberId;
con.Open();
cmd.ExecuteNonQuery();
SqlDataReader rdr = cmd.ExecuteReader();
while (rdr.Read())
{
Book newBook = new Book(rdr["ResId"].ToString(),rdr["MemberId"].ToString(),rdr["BookId"].ToString(),DateTime.Now,DateTime.Now);
return newBook;
}
}
}
}
catch
{
throw new Exception("something went wrong");
}
return null;
}
public bool CheckoutBook(string resId, string memberId)
{
using (SqlConnection con = new SqlConnection("put your db con string here"))
{
using (SqlCommand cmd = new SqlCommand("sp_CheckoutBook", con))
{
cmd.CommandType = CommandType.StoredProcedure;
cmd.Parameters.Add("#ResId", SqlDbType.VarChar).Value = resId;
cmd.Parameters.Add("#MemberId", SqlDbType.VarChar).Value = memberId;
con.Open();
cmd.ExecuteNonQuery();
SqlDataReader rdr = cmd.ExecuteReader();
while (rdr.Read())
{
if (rdr["checkoutsuccessful"].ToString() == "1")
{
return true;
}
}
}
}
return false;
}
}
}

when user returns a book:-
MySqlCommand cm1;
cm1 = new MySqlCommand("update addbook set bookquantity=bookquantity+1 where bookname='" + txt_bookname.Text + "'",con);
cm1.ExecuteNonQuery();

C# Error using Base64 convert on hash

Basically I am getting a saved hash (converted to base64) from an access database and comparing it (after converting it back) with another and should return true if they match, but for some reason it returns false. There is data in the database. I think the problem occurs when the hash is converted back from base64. Can anyone see what I am doing wrong?
private static bool MatchSHA(byte[] p1, byte[] p2)
{
bool result = false;
if (p1 != null && p2 != null)
{
if (p1.Length == p2.Length)
{
result = true;
for (int i = 0; i < p1.Length; i++)
{
if (p1[i] != p2[i])
{
result = false;
break;
}
}
}
}
return result;
}
private static byte[] GetSHA(string userID, string password)
{
SHA256CryptoServiceProvider sha = new SHA256CryptoServiceProvider();
return sha.ComputeHash(System.Text.Encoding.ASCII.GetBytes(userID + password));
}
public void RunTest()
{
string userId = "test";
string password = "Password";
string enteredPassword = "Password";
var hashedPassword = GetSHA(userId, password);
string encodedPassword = Convert.ToBase64String(hashedPassword);
try
{
string connString = (#"Provider=Microsoft.ACE.OLEDB.12.0; Data Source=|DataDirectory|Password.accdb");
OleDbConnection conn = new OleDbConnection(connString);
conn.Open();
OleDbCommand cmd = conn.CreateCommand();
cmd.CommandText = #"SELECT * FROM [Users] WHERE [UserId] = #UserId";
cmd.Parameters.AddWithValue("#UserId", userId);
OleDbDataReader dbReader = cmd.ExecuteReader();
while (dbReader.Read())
{
var compareHash = Convert.FromBase64String(dbReader["Password"].ToString());
errorLabel.Text = "Hash from DB: " + dbReader["Password"].ToString();
if (MatchSHA(compareHash, GetSHA(userId, enteredPassword)))
{
loginLabel.Text = "EnteredPassword. True";
}
else
{
loginLabel.Text = "EnteredPassword. False";
}
}
conn.Close();
}
catch (OleDbException obe)
{
errorLabel.Text = obe.ToString();
}
}