Filter and Locate does not function?
lazarus / 16-Databases

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tatamata · 2009-09-21 13:25

I don't know whether I am crazy...but it seems that Filter property
and Locate method do not work in recent snapshots. Could anybody check
this?

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tatamata · 2009-09-24 19:38

In fact, it does not work for SdfDataset and MemDataset. Could it be
because there are no indexes for these two type of datasets?
In Delphi, I think, Locate does not need indexes....

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tatamata · 2009-09-28 16:27

Definitely, for both MemDataset and SdfDataset, Locate and Filters are
not implemented, so I switched to TBufDataSet which implements both
funcionalities.
I think that lack of filters and Locate method is a huge disandvantage
of SdfDataset and MemDataset...
Anyway, it would be nice if TBufDataset is published as a component in
DataAccess page...Would it be hard to do? Is there an easy way to do
it myself?

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cdbc · 2009-09-29 14:56

Nice... questions AND answers. keep up the good work.

Can't you write a descendant memds and then look in TBufDataset source
for implementation specifics. Put it in a package and install it in
the ide? (and maybe submit it to lazarus community as a patch)

Regards Benny

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tatamata · 2009-10-08 10:04

Hello.
TMemDataSet lacks Filter and Locate functionalities, so I started to
use TBufDataSet instead.
Though I can create BufDataSets through code (add FieldDefs,
CreateDataset...) I wanted to design it through IDE (mostly because of
event properties).
So, I packaged TBufDataSet as component and published it into the IDE.
Now, I can define FieldDefs in the IDE, but, Fields collection does
not reflects FieldDefs collection. So, I create FieldDefs, but Fields
are not automatically created according to newly created FieldDefs.
Therefore, Dataset1.FieldDefs.Count=7, Dataset1.Fields.Count=0....
Any tips how to synchronize FieldDefs and Fields???

Thanks,

Zlatko