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IDProjectCategoryView StatusLast Update
0003461JEDI VCL00 JVCL Componentspublic2008-02-21 03:26
ReportermooreAssigned To 
Status closedResolutionsuspended 
Product Version3.10 
Target VersionFixed in Version 
Summary0003461: Bug en MemoryData when in CalcFields events field = Dataset.RecNo
DescriptionPut a JvMemorydata and add some fields, one of them calculated, now put in the OnCalcFields event the following:
calcfield.AsInteger := Dataset.RecNo;
run and add 2 rows, all is normal, when you want to add the 3 record, rare effect;
if in the OnCalcFields event you add other instructions, it behaves normally;
it ocurrs also with standard DBGrid..
attached a zip file
TagsNo tags attached.


related to 0003973 resolvedobones JvMemoryDataset, troubles with .RecNo 


2006-01-21 11:54 (1,798 bytes)


2006-04-04 09:07

administrator   ~0008909

Clearly, it's because (or related) to the call to UpdateCursorPos in GetRecNo, but I can't figure out why it's so bad, especially when FRecords.Count has the correct value (3)


2006-10-30 12:47

developer   ~0010397

Remco, U-C-P is under most suspicion (because other components avoid using it)
As well, it is not caught red-handed yet.

And this is true, since internals of TDataSet is one of most undocumented and twisting parts of VCL.

Sure, FRecords.Count is correct. The mess is with Buffers.
try quick look across help for TDataset.BuffersCount, .ActiveRecord, .CurrentRecord

Then do watch for ActiveRecord and CurrentRecord

Somewhere after .SetCurrentRecord there is a loop mixing .GetPriorRecord and .GetNextRecord
This methods work on some subtle nuances, never documented and perhaps erroneously implemented.

Somewhere within this loop ActiveRecord got crazy and runs up to the BuffersCount.


2008-02-21 03:26

administrator   ~0014223

This issue is too old, many changes have been done in between. Should this still be applicable, please create a new issue after having tested using the latest JVCL

Issue History

Date Modified Username Field Change
2006-01-21 11:53 moore New Issue
2006-01-21 11:54 moore File Added:
2006-04-04 09:07 obones Note Added: 0008909
2006-04-04 09:07 obones Status new => confirmed
2006-10-30 12:37 Arioch Relationship added related to 0003973
2006-10-30 12:47 Arioch Note Added: 0010397
2008-02-21 03:26 obones Status confirmed => closed
2008-02-21 03:26 obones Note Added: 0014223
2008-02-21 03:26 obones Resolution open => suspended