What might happen when user is saving into shapefile a dataset with attributes
like "long_attribute_name_01" and "long_attribute_name_02"? Truncating names
to suit the .dbf format would yield to identical names. This is how GDAL
behaves:
Attribute names can only be up to 10 characters long. Longer names will be
silently truncated. This may result in non-unique column names, which will
definitely cause problems later.
Starting with version 1.7, the OGR Shapefile driver tries to generate unique
field names. Successive duplicate field names, including those created by
truncation to 10 characters, will be truncated to 8 characters and appended
with a serial number from 1 to 99.
For example:
a → a, a → a_1, A → A_2;
abcdefghijk → abcdefghij, abcdefghijkl → abcdefgh_1
Taken from http://gdal.org/ogr/drv_shapefile.html
-Jukka Rahkonen-
________________________________________
Lähettäjä: SourceForge.net [nore...@sourceforge.net]
Lähetetty: 10. tammikuuta 2012 23:28
Vastaanottaja: SourceForge.net
Aihe: [JPP-Devel] [ jump-pilot-Bugs-3472008 ] AssertionFailedException with
two identical attribute name
Bugs item #3472008, was opened at 2012-01-10 13:28
Message generated for change (Tracker Item Submitted) made by michaudm
You can respond by visiting:
https://sourceforge.net/tracker/?func=detail&atid=679906&aid=3472008&group_id=118054
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Category: OpenJUMP - Menu - Edit
Group: None
Status: Open
Resolution: None
Priority: 5
Private: No
Submitted By: michael michaud (michaudm)
Assigned to: Nobody/Anonymous (nobody)
Summary: AssertionFailedException with two identical attribute name
Initial Comment:
How can two identical attribute names happen ?
- with a sql query : ex. select geom, name, name, name from city
(although I don't think a plain table can have duplicate names)
- it can be saved/read to/from a shapefile, a jml (with different results !)
- feature schema edition tool pevent such a schema edition
What happens ?
- a AssertionFailedException is thrown by plugins like
* combine selected layers
* clip map to fence
* there are other problems if one try to change an attribute value using its
name...
What to do ?
The minimum would be to throw a clearer message
Maybe sufficient, automatic renaming seems a bit dangerous
Refusing data loading maybe frustrating (although getting a yellow warning
light be useful)
Michaël
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