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TSQLClientDataSet Eof

Posted on 2006-07-13
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Last Modified: 2010-04-05
After I do TSQLClientDataSet.SaveToFile, Eof is true after LoadFromFile even the XML file have data content inside.

What seems to be the problem ?

Andrew
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Question by:andrewyu
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Russell Libby earned 25 total points
ID: 17101618

Andrew,
I am guessing that the SaveToFile method walks the records during the save, leaving the current row pointer at the end. Sounds like you should issue a call to the DataSet First method in order to reset the cursor location.

Regards,
Russell
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by:andrewyu
ID: 17105070
What do you meant by that ?
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by:Russell Libby
ID: 17105206
?? I am assuming you have some experience with datasets...

If the dataset is at EOF, then the dataset's cursor (current record) is located AFTER the last record in the dataset. The cause of this is most likely the SaveToFile performing something like:

DataSet.First;
while not(DataSet.Eof) do
begin
  ... export the record
  Dataset.Next;
end;

At the end of this, the DataSet's cursor is at the EOF marker. Meaning, you need to call TSQLClientDataSet.First in order to reset the cursor to the first record again.



Russell
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Author Comment

by:andrewyu
ID: 17105278
So, you suggest to call DataSet.First; before import and and export first. am i correct ?
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by:Russell Libby
ID: 17105395

Yes on the after part...
As to the before part, I would imagine that the person (who wrote the export routine) already considered this and is doing it already. The easiest way to tell is to call the DataSet's .Last method, run the SaveToFile, and confirm that all the data is written out.

Russell
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LVL 26

Expert Comment

by:Russell Libby
ID: 17105477

Btw, I didnt mean to infer that calling .First both before AND after would cause any problem. While it may be unnecessary calling it before the export, it should not hurt anything either.
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