Wsrtjtyk

I have a query that returns a list of events in a date range.

string EOOmessage = "";[enter image description here][2]

string eventText = "";

DateTime js = DateTime.Now;

DateTime je = DateTime.Now;

var itCompareDay = (from h in db.DailyGPSTables

                    where (h.EventDateTime >= startDate

                          && h.EventDateTime <= endDate)

                    select h).ToList();

I want to check the time for each event to make sure its in the proper sequence. For example JE(Job End) cannot be before JS(Job Start). I have tried many ways but this is my latest. It checks for a matching JE tag correctly but it doesn't account for which day it is in.

int rowNumber = -1;

foreach (DailyGPSTable e in itCompareDay)

{

    if (e.EventType == "JS")

    {

        js = e.EventDateTime.Value;

    }

    if (e.EventType == "JE")

    {

        je = e.EventDateTime.Value;

    }

    if (je < js)

    {

        EOOmessage = " On " + e.EventDateTime.Value.ToShortDateString() + " Job end is before Job Start " + eventText;

        errorList.Add(EOOmessage);

        errorListRow.Add(rowNumber);

    }

    rowNumber = rowNumber + 1;

}

Is there a way to check each day for out of sequence events and if found report them if not go to the next day?

Using an extension method that scans sequentially and groups while a test is true (or false) named GroupByWhile based on my extension method for scanning by pairs:

public static class IEnumerableExt {

    // TKey combineFn((TKey Key, T Value) PrevKeyItem, T curItem):

    // PrevKeyItem.Key = Previous Key

    // PrevKeyItem.Value = Previous Item

    // curItem = Current Item

    // returns new Key

    public static IEnumerable<(TKey Key, T Value)> ScanPair<T, TKey>(this IEnumerable<T> src, TKey seedKey, Func<(TKey Key, T Value), T, TKey> combineFn) {

        using (var srce = src.GetEnumerator()) {

            if (srce.MoveNext()) {

                var prevkv = (seedKey, srce.Current);



                while (srce.MoveNext()) {

                    yield return prevkv;

                    prevkv = (combineFn(prevkv, srce.Current), srce.Current);

                }

                yield return prevkv;

            }

        }

    }



    // bool testFn(T prevItem, T curItem)

    // returns groups by sequential matching bool

    public static IEnumerable<IGrouping<int, T>> GroupByWhile<T>(this IEnumerable<T> src, Func<T, T, bool> testFn) =>

        src.ScanPair(1, (kvp, cur) => testFn(kvp.Value, cur) ? kvp.Key : kvp.Key + 1)

           .GroupBy(kvp => kvp.Key, kvp => kvp.Value);

}

You can select out the interesting event types (JS/JE) ordered by EventDateTime and then group by JS followed by JE and throw out matching pairs:

var itCompareDay = (from h in db.DailyGPSTables

                    where (h.EventDateTime >= startDate

                          && h.EventDateTime <= endDate)

                    orderby h.EventDateTime

                    select h).ToList();



var errEvents = itCompareDay

                    .Select((ev, rowNum) => new { ev.EventType, ev.EventDateTime, rowNum })

                    .Where(cd => cd.EventType == "JS" || cd.EventType == "JE")

                    .GroupByWhile((pd, cd) => pd.EventType == "JS" && cd.EventType == "JE" && pd.EventDateTime.Date == cd.EventDateTime.Date)

                    .Where(cdg => cdg.Count() != 2)

                    .SelectMany(cdg => cdg.Select(cd => new { cd.rowNum, ErrMsg = cd.EventType == "JE" ? "JE without preceding JS" : "JS without following JE" }));

Note that rowNum is 0 based but you could add 1 in the first Select if desired.