#property description "Example of using the CalendarValueLastByEvent function"
#property description " for tracking the release of the Nonfarm Payrolls report."
#property description "To achieve this, get the current change ID"
#property description " of the Calendar database. Then, use this ID to receive"
#property description " only new events via the timer survey"
//+------------------------------------------------------------------+
//| Expert initialization function |
//+------------------------------------------------------------------+
int OnInit()
{
//--- create timer
EventSetTimer(60);
//---
return(INIT_SUCCEEDED);
}
//+------------------------------------------------------------------+
//| Expert deinitialization function |
//+------------------------------------------------------------------+
void OnDeinit(const int reason)
{
//--- destroy timer
EventKillTimer();
}
//+------------------------------------------------------------------+
//| Expert tick function |
//+------------------------------------------------------------------+
void OnTick()
{
//---
}
//+------------------------------------------------------------------+
//| Timer function |
//+------------------------------------------------------------------+
void OnTimer()
{
//--- Calendar database change ID
static ulong calendar_change_id=0;
//--- first launch attribute
static bool first=true;
//--- event ID
static ulong event_id=0;
//--- event name
static string event_name=NULL;
//--- event value array
MqlCalendarValue values[];
//--- perform initialization - get the current calendar_change_id
if(first)
{
MqlCalendarEvent events[];
//--- country code for USA (ISO 3166-1 Alpha-2)
string USA_code="US";
//--- get events for USA
int events_count=CalendarEventByCountry(USA_code,events);
//--- position of a necessary event in the 'events' array
int event_pos=-1;
//--- display USA events in the Journal
if(events_count>0)
{
PrintFormat("%s: USA events: %d",__FUNCTION__,events_count);
for(int i=0;i<events_count;i++)
{
string event_name_low=events[i].name;
//--- change an event name to lower case
if(!StringToLower(event_name_low))
{
PrintFormat("StringToLower() returned %d error",GetLastError());
//--- exit the function ahead of time
return;
}
//--- look for the "Nonfarm Payrolls" event
if(StringFind(event_name_low,"nonfarm payrolls")!=-1)
{
//--- event found, remember its ID
event_id=events[i].id;
//--- write the "Nonfarm Payrolls" event name
event_name=events[i].name;
//--- remember the events' position in the 'events[]' array
event_pos=i;
//--- keep in mind that the Calendar features several events containing "nonfarm payrolls" in their names
PrintFormat("Event \"Nonfarm Payrolls\" found: event_id=%d event_name=%s",event_id,event_name);
//--- view all the events by commenting out the 'break' operator to better understand this example
break;
}
}
//--- reduce the list by deleting events after "Nonfarm Payrolls"
ArrayRemove(events,event_pos+1);
//--- leave 9 events before "Nonfarm Payrolls" for more convenient analysis
ArrayRemove(events,0,event_pos-9);
ArrayPrint(events);
}
else
{
PrintFormat("%s: CalendarEventByCountry(%s) returned 0 events, error code=%d",
USA_code,__FUNCTION__,GetLastError());
//--- operation completed in a failure, try again during the next call of the timer
return;
}
//--- get the Calendar database change ID for the specified event
if(CalendarValueLastByEvent(event_id,calendar_change_id,values)>0)
{
//--- this code block cannot be executed during the first launch but let's add it anyway
PrintFormat("%s: Received the Calendar database current ID: change_id=%d",
__FUNCTION__,calendar_change_id);
//--- set the flag and exit before the timer's next event
first=false;
return;
}
else
{
//--- data are not received (this is normal for the first launch), check for an error
int error_code=GetLastError();
if(error_code==0)
{
PrintFormat("%s: Received the Calendar database current ID: change_id=%d",
__FUNCTION__,calendar_change_id);
//--- set the flag and exit before the timer's next event
first=false;
//--- now we have the calendar_change_id value
return;
}
else
{
//--- and this is really an error
PrintFormat("%s: Failed to get values for event_id=%d",__FUNCTION__,event_id);
PrintFormat("Error code: %d",error_code);
//--- operation completed in a failure, try again during the next call of the timer
return;
}
}
}
//--- we have the last known value of the Calendar change ID (change_id)
ulong old_change_id=calendar_change_id;
//--- check for a new Nonfarm Payrolls event value
if(CalendarValueLastByEvent(event_id,calendar_change_id,values)>0)
{
PrintFormat("%s: Received new events for \"%s\": %d",
__FUNCTION__,event_name,ArraySize(values));
//--- display data from the 'values' array in the Journal
ArrayPrint(values);
//--- display the values of the previous and new Calendar IDs in the Journal
PrintFormat("%s: Previous change_id=%d, new change_id=%d",
__FUNCTION__,old_change_id,calendar_change_id);
/*
write your code that is to handle "Nonfarm Payrolls" data release here
*/
}
//---
}
/*
Result:
OnTimer: USA events: 202
Event "Nonfarm Payrolls" found: event_id=840030016 event_name=Nonfarm Payrolls
[id] [type] [sector] [frequency] [time_mode] [country_id] [unit] [importance] [multiplier] [digits] [source_url] [event_code] [name] [reserved]
[0] 840030007 1 4 2 0 840 1 1 0 1 "https://www.bls.gov" "consumer-price-index-yy" "CPI y/y" 0
[1] 840030008 1 4 2 0 840 1 1 0 1 "https://www.bls.gov" "consumer-price-index-ex-food-energy-yy" "Core CPI y/y" 0
[2] 840030009 1 4 2 0 840 0 1 0 3 "https://www.bls.gov" "consumer-price-index-nsa" "CPI n.s.a." 0
[3] 840030010 1 4 2 0 840 0 1 0 3 "https://www.bls.gov" "consumer-price-index-ex-food-energy" "Core CPI" 0
[4] 840030011 1 4 2 0 840 1 1 0 1 "https://www.bls.gov" "import-price-index-mm" "Import Price Index m/m" 0
[5] 840030012 1 4 2 0 840 1 1 0 1 "https://www.bls.gov" "import-price-index-yy" "Import Price Index y/y" 0
[6] 840030013 1 4 2 0 840 1 1 0 1 "https://www.bls.gov" "export-price-index-mm" "Export Price Index m/m" 0
[7] 840030014 1 4 2 0 840 1 1 0 1 "https://www.bls.gov" "export-price-index-yy" "Export Price Index y/y" 0
[8] 840030015 1 3 2 0 840 1 2 0 1 "https://www.bls.gov" "unemployment-rate" "Unemployment Rate" 0
[9] 840030016 1 3 2 0 840 4 3 1 0 "https://www.bls.gov" "nonfarm-payrolls" "Nonfarm Payrolls" 0
OnTimer: Received the Calendar database current ID: change_id=33986560
*/
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