delphi - How to recreate exceptions of recurring appointment in the proper order? -

i have following issue:

• assume recurring event on 15, 19, 23, 27... february
• in exchange '19' occurrence moved 21
• next, '15' occurrence moved 20. moves past original start date (19) of 2nd occurrence

now if want recreate recurring event in exchange first create master event, i.e. automatically regular occurrences, , must modify of these create exceptions in same order. if don't , first create '15->20' occurrence, fail, because modified date past regular '19' occurrence.
exchange give me modified occurrence crossing or overlapping adjacent occurrence error.

but how determine order? in simple test case getitem call master event not give me modifiedoccurrences in order in created:

 <t:modifiedoccurrences>     <t:occurrence>        <t:itemid id="aamka[snip]pqaaea==" changekey="dwa[snip]bix"/>        <t:start>2016-02-20t09:00:00z</t:start>        <t:end>2016-02-20t10:30:00z</t:end>        <t:originalstart>2016-02-15t09:00:00z</t:originalstart>     </t:occurrence>     <t:occurrence>        <t:itemid id="aamka[snip]pqaaea==" changekey="dwa[snip]bix"/>        <t:start>2016-02-21t09:00:00z</t:start>        <t:end>2016-02-21t10:30:00z</t:end>        <t:originalstart>2016-02-19t09:00:00z</t:originalstart>     </t:occurrence>  </t:modifiedoccurrences> 

if getitem 2 exceptions see no appointment property can use determine order in created:

• lastmodifiedtime not anything, exceptions may have been modified repeatedly.
• originalstart or recurrenceid (a date equal originalstart) don't work, because process goes in both directions (the exceptions can back in time).
• i see no other properties in calenderitem documentation seem usable.

i tried create master with exceptions in 1 step, inserting same modifiedoccurrences block in createitem call gives schema validation error because have supply itemids (but exchange creates those.)

so how can determine in order must recreate these exceptions (or did overlook , is possible create master event exceptions in 1 step)?

found answer. crucial remark in question was:

originalstart or recurrenceid (a date equal originalstart) don't work, because process goes in both directions (the exceptions can in time).

if split forward , backward occurrence moves , handle them in 2 blocks, works. actually, 3 blocks:

1. remove deleted occurrences

2. create occurrences moved forward (start > originalstart) last date first date

3. create occurrences moved backward (start < originalstart) first date last date

essential parts of (delphi xe2) code using developer express components:

type     tiddate = class                 forgstart,                 fstart   : tdatetime;                 findex   : integer;                 constructor create(aorgstart,astart: tdatetime; aindex: integer);              end;  constructor tiddate.create(aorgstart,astart: tdatetime; aindex: integer); begin    forgstart := aorgstart;    fstart    := astart;    findex    := aindex; end;  function tdatamodulesyncexchange.insertexchangemasterevent(amasterevent: tcxschedulerevent; var amasteritemid, amasterentryid: string): boolean; var    lexchoccurrence: tcxschedulerevent;                 : integer;    ldatelist      : tobjectlist;    liddate        : tiddate;    leventlist     : tcxschedulereventlist;  begin { main insertexchangemasterevent }    [snip]    leventlist := amasterevent.getrecurrencechain;  // devex code     // 1. deleted occurrences     := 0 leventlist.count-1    begin       lexchoccurrence := leventlist.items[i];       if lexchoccurrence.eventtype = etexception          deleteexchangeitem(loccuritemid);  // own code elsewhere    end;     // 2. occurrences moved forward (start > originalstart) last date first date    ldatelist := tobjectlist.create(true);    := 0 leventlist.count-1    begin       lexchoccurrence := leventlist.items[i];       if lexchoccurrence.eventtype = etcustom       begin          liddate := tiddate.create(lexchoccurrence.getoriginaldate,lexchoccurrence.start,i);          ldatelist.add(liddate);       end;    end;    ldatelist.sortlist(function (item1, item2: pointer): integer                       var ldt1,ldt2: tdatetime;                       begin                          ldt1 := tiddate(item1).forgstart;                          ldt2 := tiddate(item2).forgstart;                          if ldt1 > ldt2                             result := 1                          else                             if ldt1 < ldt2                                result := -1                             else                               result := 0;                       end);     := ldatelist.count-1 downto 0       tiddate(ldatelist[i])          if fstart > forgstart             createoccurrence(findex,loccurchangekey);   // own code elsewhere     // 3. occurrences moved backward (start < originalstart) first date last date    := 0 ldatelist.count-1       tiddate(ldatelist[i])          if fstart < forgstart             createoccurrence(findex,loccurchangekey);   // own code elsewhere     ldatelist.free;