Sdfdataset Component
lazarus / 31-LCL

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vonskie · 2014-03-05 16:02

Have the following text file all fields are tab delimited

First line is the column name
Second line is the measurement type
third line data starts

How would I set up the component?

Would I tell it the first line is the schema?

How would I setup fielddefs?

What does filtered setting do?

How would the schema look for the tstring box?

I can find no example or faq on its use or no doc.

Please assist.

Time           Date            CH1        CH2        CH3         
      °C         °C         °C         °C          
08:49:57   3/4/2014    4.2000e+000    1.9300e+001   -1.4800e+001   
09:04:57   3/4/2014    4.6000e+000    1.8900e+001   -1.4900e+001   
09:19:57   3/4/2014    4.4000e+000    1.8400e+001   -1.5200e+001   
09:34:57   3/4/2014    4.6000e+000    1.8900e+001   -1.5000e+001   
09:49:57   3/4/2014    4.5000e+000    1.9000e+001   -1.5200e+001

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howardpc · 2014-03-05 20:41

Quote from: vonskie on March 05, 2014, 05:02:53 pmHow would I set up
the component?
Code: [Select]  sdf.FirstLineAsSchema:=True;
  sdf.FileMustExist:=True;
  sdf.Delimiter:=#9;
  sdf.FileName:='yourfilename.txt'; 

QuoteWould I tell it the first line is the schema?
Yes. However, note that your second line of data is really metadata,
and would be part of a more complex schema if 'schema' were not
restricted to one line. So although the TSDFDataset will read the
second line data OK, if displayed in a DBGrid the values shown would
not correspond to the column titles.

QuoteHow would I setup fielddefs?
There is no need to do this since you provide a schema, so the
TSDFDataset component parses the first data line and sets up fielddefs
for you.

QuoteWhat does filtered setting do?
It enables you to make use of the OnFilterRecord event to process in-
memory data

QuoteHow would the schema look for the tstring box?
I don't understand your question.

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BigChimp · 2014-03-06 10:29

Quote from: vonskie on March 05, 2014, 05:02:53 pmI can find no
example or faq on its use or no doc.
http://wiki.freepascal.org/Lazarus_Database_Overview#TSdfDataset_and_T
FixedDataset

No idea if the linked example is current/needs updates. It seems to
set both schema as well as get the schema from the file, which as
Howard says shouldn't be necessary.