Questions from Beginners MQL5 MT5 MetaTrader 5 - page 1219

[Pineapple88]

Vladimir Karputov:

It looks like the terminal keeps pumping up the history - so the indicator keeps recalculating. Or another variant: you have a VERY large number of bars set in the terminal for display on the chart, and your computer has a VERY large number of bars on the chart.

Thanks for the help!

When you select a different date, the calculation takes place immediately. In the first test there was a gap in price, possibly missing some prices - this is most likely the problem.

[Green handsome]

Hello! There is an MT5 indicator "Grid Builder" which drawshorizontal lines in price increments. You can select e.g. 100p, 200p etc. And it builds a horizontal grid up and down with a given step. But it has one problem, for example, when I draw horizontal levels on timeframe H4 (I put horizontal lines from drawing tools in the terminal) and switch to any other timeframe, all my lines are removed. Only horizontal indicator levels remain. How can I correct this error in the code? To ensure that my horizontal levels are never deleted. Here is the indicator code (I wrote this question in another thread, but there is no answer yet)

//+------------------------------------------------------------------+
//|                                                  GridBuilder.mq5 |
//|                                              Copyright 2015, AM2 |
//|                                     https://www.forexsystems.biz |
//+------------------------------------------------------------------+
#property copyright "Copyright 2015, AM2"
#property link      "https://www.forexsystems.biz"
#property version   "1.00"
#property indicator_chart_window

//---- для расчёта и отрисовки индикатора использовано ноль буферов
#property indicator_buffers 0
//---- использовано всего ноль графических построений
#property indicator_plots   0
//--- входные параметры 
input int count = 50;      //количество линий вверх вниз от цены
input int step  = 333;     //шаг линий 
input double pr = 1.4622;  //цена от которой пляшем
//+------------------------------------------------------------------+
//| Custom indicator initialization function                         |
//+------------------------------------------------------------------+
int OnInit()
  {
//--- indicator buffers mapping
   ObjectsDeleteAll(0,0,OBJ_HLINE);
//---
   return(INIT_SUCCEEDED);
  }
//+------------------------------------------------------------------+
//| Expert deinitialization function                                 |
//+------------------------------------------------------------------+
void OnDeinit(const int reason)
  {
   Comment("");
   ObjectsDeleteAll(0,0,OBJ_HLINE);
  }
//+------------------------------------------------------------------+ 
//| Создает горизонтальную линию                                     | 
//+------------------------------------------------------------------+ 
bool HLine(const string name="HLine",double price=0)
  {
//--- создадим горизонтальную линию 
   if(!ObjectCreate(0,name,OBJ_HLINE,0,0,price))
     {
      Print(__FUNCTION__,
            ": не удалось создать горизонтальную линию! Код ошибки = ",GetLastError());
      return(false);
     }
//--- установим цвет линии 
   ObjectSetInteger(0,name,OBJPROP_COLOR,clrGreen);
   ObjectSetInteger(0,name,OBJPROP_WIDTH,1);
   return(true);
  }
//+------------------------------------------------------------------+
//| Custom indicator iteration function                              |
//+------------------------------------------------------------------+
int OnCalculate(const int rates_total,
                const int prev_calculated,
                const datetime &time[],
                const double &open[],
                const double &high[],
                const double &low[],
                const double &close[],
                const long &tick_volume[],
                const long &volume[],
                const int &spread[])
  {
   double price=pr;
//--- создадим горизонтальную линию 
   for(int i=0;i<=count;i++)
     {
      HLine("HLine"+(string)i,price+step*i*_Point);
      HLine("HLine"+(string)(i+count+1),price-step*i*_Point);
     }
//--- return value of prev_calculated for next call
   return(rates_total);
  }
//+------------------------------------------------------------------+

[Artyom Trishkin]

Александр:

Hello! There is an MT5 indicator "Grid Builder" which drawshorizontal lines in price increments. You can select e.g. 100p, 200p etc. And it builds a horizontal grid up and down with a given step. But it has one problem, for example, when I draw horizontal levels on timeframe H4 (I put horizontal lines from drawing tools in the terminal) and switch to any other timeframe, all my lines are removed. Only horizontal indicator levels remain. How can I correct this error in the code? To ensure that my horizontal levels are never deleted. Here is the code of indicator (I wrote this question in another topic, but there is no answer)

Do pay attention to this code:

//+------------------------------------------------------------------+
//| Expert deinitialization function                                 |
//+------------------------------------------------------------------+
void OnDeinit(const int reason)
  {
   Comment("");
   ObjectsDeleteAll(0,0,OBJ_HLINE);
  }
//+------------------------------------------------------------------+ 

In particular, read about ObjectsDeleteAll() - there the cause and answer for correction.

[Green handsome]

Artyom Trishkin:

Pay attention to this code:

In particular read about ObjectsDeleteAll() - there's the reason and the answer on how to tweak it.

Thank you!!! Sorted it out, now it works without deletion.

[Dmitri Custurov]

Are SQLite database operations available from the tester ? I mean adding and changing data.

[Alexey Viktorov]

Dmitri Custurov:
Are SQLite database operations available from the tester? I mean adding and changing data.

Available. Just keep an eye on the location of the base. They are created in the same way as the files.

[Dmitri Custurov]

Alexey Viktorov:

Available. Just keep an eye on the location of the base. They are created just like the files.

#define  DB_NAME "OHLC_DB"

int db_handle;
string TableName;
//+------------------------------------------------------------------+
//| Expert initialization function                                   |
//+------------------------------------------------------------------+
int OnInit(){
   db_handle = DatabaseOpen(DB_NAME, DATABASE_OPEN_READWRITE|DATABASE_OPEN_CREATE); 

   if (db_handle != INVALID_HANDLE){
      Print(StringFormat("Database %s was opened", DB_NAME));
      
      TableName = Symbol() + "_" + enumTimeFrameToString(Period());
      if (DatabaseTableExists(db_handle, TableName)){
         Print(StringFormat("Table %s is exist", TableName));
      }else{
         if (DatabaseExecute(db_handle, "CREATE TABLE " + TableName + "("
                             "TIME TEXT PRIMARY KEY  NOT NULL,"
                             "OPEN              REAL NOT NULL,"
                             "HIGH              REAL NOT NULL,"
                             "LOW               REAL NOT NULL,"
                             "CLOSE             REAL NOT NULL );")){
            Print(StringFormat("Table %s was created", TableName));
            string time = "'" + TimeToString(iTime(Symbol(), PERIOD_CURRENT, 0)) + "'";
            double open = iOpen(Symbol(), PERIOD_CURRENT, 0);
            double high = iHigh(Symbol(), PERIOD_CURRENT, 0);
            double low = iLow(Symbol(), PERIOD_CURRENT, 0);
            double close = iClose(Symbol(), PERIOD_CURRENT, 0);

            if (!DatabaseExecute(db_handle,"INSERT INTO " + TableName + " (TIME,OPEN,HIGH,LOW,CLOSE) "
                                           "VALUES (" + StringFormat("%s,%.5f,%.5f,%.5f,%.5f", time, open, high, low, close) + ");")){
               Print("Table: ", TableName, " insert failed with code ", GetLastError());
               DatabaseClose(db_handle);
               return(INIT_FAILED);
            }else
               Print("New table started:");   
         }else{
            Print(StringFormat("Could not create %s table. Error is: %d", TableName, GetLastError()));
            DatabaseClose(db_handle);
            return(INIT_FAILED); 
         }
      }
      
      return(INIT_SUCCEEDED);
   }else{
      Print("Could not open db. Error is: ", GetLastError());
      return(INIT_FAILED); 
   }     
}
//+------------------------------------------------------------------+
//| Expert deinitialization function                                 |
//+------------------------------------------------------------------+
void OnDeinit(const int reason){
   DatabaseClose(db_handle);
}
//+------------------------------------------------------------------+
//| Expert tick function                                             |
//+------------------------------------------------------------------+
void OnTick(){
   string time = "'" + TimeToString(iTime(Symbol(), PERIOD_CURRENT, 0)) + "'";
   double open = iOpen(Symbol(), PERIOD_CURRENT, 0);
   double high = iHigh(Symbol(), PERIOD_CURRENT, 0);
   double low = iLow(Symbol(), PERIOD_CURRENT, 0);
   double close = iClose(Symbol(), PERIOD_CURRENT, 0);
   if (!DatabaseExecute(db_handle,"INSERT INTO " + TableName + " (TIME,OPEN,HIGH,LOW,CLOSE) "
                                  "VALUES (" + StringFormat("%s,%.5f,%.5f,%.5f,%.5f", time, open, high, low, close) + ");")){
      Print("Table: ", TableName, " insert failed with code ", GetLastError());
      DatabaseClose(db_handle);
   }   
}
//+------------------------------------------------------------------+
string enumTimeFrameToString(ENUM_TIMEFRAMES frame){
   switch(frame){
      case PERIOD_M1:  return "M1";
      case PERIOD_M2:  return "M2";
      case PERIOD_M3:  return "M3";
      case PERIOD_M4:  return "M4";
      case PERIOD_M5:  return "M5";
      case PERIOD_M6:  return "M6";
      case PERIOD_M10: return "M10";
      case PERIOD_M12: return "M12";
      case PERIOD_M15: return "M15";
      case PERIOD_M20: return "M20";
      case PERIOD_M30: return "M30";
      case PERIOD_H1:  return "H1";
      case PERIOD_H2:  return "H2";
      case PERIOD_H3:  return "H3";
      case PERIOD_H4:  return "H4";
      case PERIOD_H6:  return "H6";
      case PERIOD_H8:  return "H8";
      case PERIOD_D1:  return "D1";
      case PERIOD_W1:  return "W1";
      default:         return "MN1";
   }
}

Here is my code. In the initialization it creates one record in the table. In the OnTick body it should immediately return an error, because I try to add a record with the same PRIMARY KEY, and after that the base closes immediately. But at the same time I should see at least that first record when I open it, but when I run it in the tester it's not there. And even the table is not created. If I just open it in the terminal, everything is normal. The first record is there.

[[Deleted]]

Dmitri Custurov:

Here is my code. In the initialization it creates one record in the table. In the OnTick body it should immediately return an error, because I try to add a record with the same PRIMARY KEY, and after that the base closes immediately. But at the same time I should see at least that first record when I open it, but when I run it in the tester it's not there. And even the table is not created. If I just open it in the terminal, everything is normal. The first record is there.

Once again I am convinced that the tester and the terminal itself are different hypostases...

[Kang Feng]

HistorySelect(xxx,TimeCurrent()) miss the latest history order / deal sometimes. Now you have to use HistorySelect(xxx,TimeCurrent()+1) To get a more accurate result.

[Vladimir Karputov]

tickfenix:

It has long been recommended to add one day toTimeCurrent(). It's just that now, in response to your not quite correct code, the terminal is giving you advice.