[SOLVED] Obtain the DataType of selected grid column?
lazarus / 16-Databases

----------------------------------------------------------------------
Elmug · 2012-06-29 06:49

Hi everyone,

SQLite3, Windows7, SQLite3Connection:

I would like to detect the datatype of the selected or current grid
column.

Since we have DBGrid1.SelectedColumn.FieldName and I have used it
alredy, is there perhaps a similar equivalent, perhaps like
DBGrid1.SelectedColumn.DataType?

If so, I would appreciate info on it, or a way to obtain the DataType
of the current column in the Grid.

Thanks a lot!

----------------------------------------------------------------------
Lacak2 · 2012-06-29 08:03

Quote from: Elmug on June 29, 2012, 08:49:35 amSince we have
DBGrid1.SelectedColumn.FieldName and I have used it alredy, is there
perhaps a similar equivalent, perhaps like
DBGrid1.SelectedColumn.DataType?
Exactly

----------------------------------------------------------------------
BigChimp · 2012-06-29 08:27

Long live autocompletion (type a period after your object, then ctrl-
space - it shows you all possible properties and methods/functions of
an object)... or F1 or right click, show declaration...

----------------------------------------------------------------------
Elmug · 2012-06-29 08:34

Thank you a lot, Lacak2 and BigChimp.

I think this will solve what I needed in relation to doing some
dynamics to tables with Memos.

With what you are expaining now, BigChimp, I will at least now be on a
bycicle, rather than on foot. I really needed to know that.

Best of all to all.

----------------------------------------------------------------------
BigChimp · 2012-06-29 08:42

Yep - not being able to find these things out yourselves can be
incredibly annoying...

----------------------------------------------------------------------
Elmug · 2012-06-29 10:00

Hi, fellows, again:

Unfortunately, it seems that DataType is not available as wished.

I added this line:
Edit1.Text := DBGrid1.SelectedColumn.DataType; 
and the error message is:
identifier idents no menber "DataType"


Also, the autocomplete does show the member FieldName, but does not
show "DataType" as available .

I would appreciate some other suggestions.

Thanks again!

----------------------------------------------------------------------
ludob · 2012-06-29 13:19

And what about
Code: [Select]DBGrid1.SelectedField.DataType; 
Documentation is here: http://lazarus-
ccr.sourceforge.net/docs/lcl/dbgrids/tcustomdbgrid.html

----------------------------------------------------------------------
Elmug · 2012-06-29 19:03

Quote from: ludob on June 29, 2012, 03:19:59 pmAnd what about
Code: [Select]DBGrid1.SelectedField.DataType; 
Documentation is here: http://lazarus-
ccr.sourceforge.net/docs/lcl/dbgrids/tcustomdbgrid.html

Hi Ludob, much appreciation for the tip.

SelectedField.DataType is available, and likely can solve what I am
trying to do.

I am off to studying how to deal with TranslateString types, for this,
and will report back.

Thanks!

----------------------------------------------------------------------
Elmug · 2012-06-30 07:37

Hi everyone,

I got it working now, as follows:

// This procedure puts the datatype of TDBGrid's current cell into a
TEdit box
PROCEDURE TForm1.DBGrid1ColEnter(Sender: TObject);
VAR X: TFieldType;
BEGIN
   X:= DBGrid1.SelectedField.DataType; //X here obtains datatype of
Grid's selected cell
   //So, use FldToStr function, placed at implementation section,
   //to get datatype in text-readable form, and put it into a TEdit
box
     E_FieldDataType.Text :=  FldToStr(X); {E_FieldDataType is the
TEdit box}
END;            
//Note: Function FldToStr (USES Unit Db) was used exactly as found
from: 

http://www.codepedia.com/1/FieldToStr

and am including it below, for convenience:
Code: [Select]function FldToStr: String;  //(const Value : TFieldType)
: String;
begin
   Case Value of
   ftUnknown    :  FldToStr := 'Unknown';
   ftString     :  FldToStr := 'String';
   ftSmallint   :  FldToStr := 'SmallInt';
   ftInteger    :  FldToStr := 'Integer';
   ftWord       :  FldToStr := 'Word';
   ftBoolean    :  FldToStr := 'Boolean';
   ftFloat      :  FldToStr := 'Float';
   ftCurrency   :  FldToStr := 'Currency';
   ftBCD        :  FldToStr := 'BCD';
   ftDate       :  FldToStr := 'Date';
   ftTime       :  FldToStr := 'Time';
   ftDateTime   :  FldToStr := 'DateTime';
   ftBytes      :  FldToStr := 'Bytes';
   ftVarBytes   :  FldToStr := 'VarBytes';
   ftAutoInc    :  FldToStr := 'AutoInc';
   ftBlob       :  FldToStr := 'Blob';
   ftMemo       :  FldToStr := 'Memo';
   ftGraphic    :  FldToStr := 'Graphic';
   ftFmtMemo    :  FldToStr := 'FmtMemo';
   ftParadoxOle :  FldToStr := 'ParadoxOle';
   ftDBaseOle   :  FldToStr := 'DBaseOle';
   ftTypedBinary: FldToStr := 'TypedBinary';
   ftCursor     :  FldToStr := 'Cursor';
   ftFixedChar  :  FldToStr := 'FixedChar';
   ftWideString :  FldToStr := 'WideString';
   ftLargeint   :  FldToStr := 'LargeInt';
   ftADT        :  FldToStr := 'ADT';
   ftArray      :  FldToStr := 'Array';
   ftReference  :  FldToStr := 'Reference';
   ftDataSet    :  FldToStr := 'DataSet';
   ftOraBlob    :  FldToStr := 'OraBlob';
   ftOraClob    :  FldToStr := 'OraClob';
   ftVariant    :  FldToStr := 'Variant';
   ftInterface  :  FldToStr := 'Interface';
   ftIDispatch  :  FldToStr := 'IDispatch';
   ftGuid       :  FldToStr := 'GUID';
   ftTimeStamp  :  FldToStr := 'TimeStamp';
   ftFMTBcd     :  FldToStr := 'FMTBcd';
   end;
end;

Thank you all for helping me resolve this!

----------------------------------------------------------------------
ludob · 2012-06-30 08:10

QuoteI got it working now, as follows:Good 

Shorter:
Code: [Select]E_FieldDataType.Text:=Fieldtypenames[dbgrid1.SelectedFie
ld.DataType];
Documentation: http://www.freepascal.org/docs-
html/fcl/db/fieldtypenames.html

----------------------------------------------------------------------
Elmug · 2012-06-30 09:06

Quote from: ludob on June 30, 2012, 10:10:37 amQuoteI got it working
now, as follows:Good 

Shorter:
Code: [Select]E_FieldDataType.Text:=Fieldtypenames[dbgrid1.SelectedFie
ld.DataType];
Documentation: http://www.freepascal.org/docs-
html/fcl/db/fieldtypenames.html

BEAUTIFUL!

I just tested your MUCH shorter way and worked the first time and will
use it instead.
Its like from bicycle to airplane!  (It took me 2 days the long way).

Thanks!

----------------------------------------------------------------------
ludob · 2012-06-30 09:55

QuoteIt took me 2 days the long way.It took me 5 minutes to look it up
in the documentation. Perhaps you should start there

----------------------------------------------------------------------
KpjComp · 2012-06-30 12:41

There is another trick you can use too.

Say if Fieldtypenames array had not been defined, you could use type
info.

eg.
Code: [Select]function FieldTypeToString(f:TFieldType):string;
begin
  result := copy( getenumname(typeinfo(TFieldType),ord(f)), 3, 100);
end;

----------------------------------------------------------------------
Elmug · 2012-06-30 17:09

Quote from: ludob on June 30, 2012, 11:55:05 amQuoteIt took me 2 days
the long way.It took me 5 minutes to look it up in the documentation.
Perhaps you should start there

Unfortunately, I always have to start from where I am (most of the two
days was READING documentation and all the web would show).

Now I am a little further, though, and I appreciate the help.

----------------------------------------------------------------------
Elmug · 2012-06-30 17:16

Quote from: KpjComp on June 30, 2012, 02:41:08 pmThere is another
trick you can use too.

Say if Fieldtypenames array had not been defined, you could use type
info.

eg.
Code: [Select]function FieldTypeToString(f:TFieldType):string;
begin
  result := copy( getenumname(typeinfo(TFieldType),ord(f)), 3, 100);
end;

Thanks KpjComp.

Good tip.....I think the array is predefined by the Unit DB, so the
doing just takes the one-line ludob gives, with no need to define a
function. I had no need to define any array.

----------------------------------------------------------------------
KpjComp · 2012-06-30 18:48

QuoteI think the array is predefined by the Unit DB

Yes, that's why I said "Say if Fieldtypenames array had not been
defined,".
I only pointed out for future reference, where you might want to get
the Names of other Enums.

----------------------------------------------------------------------
Elmug · 2012-06-30 21:59

Quote from: KpjComp on June 30, 2012, 08:48:23 pmQuoteI think the
array is predefined by the Unit DB

Yes, that's why I said "Say if Fieldtypenames array had not been
defined,".
I only pointed out for future reference, where you might want to get
the Names of other Enums.

I do find your tip very helpful and useful and as guide to many other
possibilities, and for my further studying and understanding.

Thank you.