[Shapelib] can't DBFAddField after DBFCloneEmpty

[Frank Warmerdam]

Jeff D. Hamann wrote:
> shapelib'ers:
> 
> I have been trying to use the DBFAddField() after calling 
> DBFCloneEmpty() with little success. I have been able to generate empty 
> files with new fields, but what I need to accomplish to append and 
> populate fields to an existing shapefile.
> 
> hDBF_Soln = DBFCreate( "results/shapes/test.dbf" );
> bid_idx         = DBFAddField( hDBF_Soln, "bid",        FTInteger,  3, 0 );
> period_idx      = DBFAddField( hDBF_Soln, "period",     FTInteger,  3, 0 );
> 
> works fine:
> 
> hDBF_Soln = DBFCloneEmpty( hDBF, "results/shapes/test.dbf" );
> period_idx      = DBFAddField( hDBF_Soln, "period",     FTInteger,  3, 0 );
> 
> does not. Shouldn't these be the same if the original shapefile only 
> contains one field names "bid"?


Jeff,

Shapelib's dbf code does not support adding fields to .dbf files with
records already in the file.  You will either need to create a new file,
with the old + new fields, and copy over the existing records or use
something else.

I will note it wouldn't be that hard to modify DBFAddField() to reshuffle
the file to add in fields in a file with records.  So if you are skilled,
and so inclined feel free to take a crack at the code.

Best regards,
-- 
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I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
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