when columns have the same name, styling with the first one does not work

[qgib]

Author Name: Paolo Cavallini (@pcav)
Original Redmine Issue: 12713
Affected QGIS version: 3.0.0
Redmine category:vectors

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new description:

#20819 (comment)

old description:

This file:
http://www.faunalia.eu/~paolo/qgis/result.zip
resulting from
processing.runalg("saga:gridstatisticsforpolygons","/tmp/RESULT.tif","/path/municipalities.shp",False,False,True,False,True,False,False,False,0,None)
seems impossible to thematize on the basis of the Calculated column.
If saved as a new shapefile, it is OK. Possibly SAGA produces a wrong dbf?

[qgib]

Author Name: Even Rouault (@rouault)

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Examination with ogrinfo shows that there are in fact 2 columns with same name "Calculated" (and with different values), which must confuse QGIS.

[qgib]

Author Name: Paolo Cavallini (@pcav)

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Merci Even for checking. So this should be either an issue of Processing, not giving appropriate column names, or upstream (saga).

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• fixed_version_id was configured as Future Release - High Priority
• category_id was changed from Symbology to Processing/SAGA

[qgib]

Author Name: Giovanni Manghi (@gioman)

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There are two issues here, but the real one seems a qgis issue.

The SAGA module gridstatisticsforpolygons creates an output shapefile where the statistics are placed into columns that are called "nameoftheinputraster [nameofthestatistics]" and this is very likely to hit the 10 char limit for column names. So the result is likely to have different columns that have the exactly same name (the first 10 chars of input raster), and this is confirmed by ogrinfo of course.

When opening a shapefile with at least two columns with the exact same name, ex: "columnname", qgis "changes" the name of the 2nd, 3rd... to "columnname_1", "columnname_2", etc. Styling using the values for this "renamed" columns works, but not for the first one.

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• version was changed from 2.8.1 to master
• status_id was changed from Open to Feedback
• category_id was changed from Processing/SAGA to Vectors
• subject was changed from Shp cannot be stylized to shapefile cannot be stylized when columns have the same name

[qgib]

Author Name: Giovanni Manghi (@gioman)

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• status_id was changed from Feedback to Open

[qgib]

Author Name: Giovanni Manghi (@gioman)

---

• subject was changed from shapefile cannot be stylized when columns have the same name to when columns have the same name, styling with the first one does not work

[qgib]

Author Name: Giovanni Manghi (@gioman)

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• regression was configured as 0
• easy_fix was configured as 0

[qgib]

Author Name: Jürgen Fischer (@jef-n)

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• description was changed from new description:

https://issues.qgis.org/issues/12713#note-3

old description:

This file:
http://www.faunalia.eu/~paolo/qgis/result.zip
resulting from
processing.runalg("saga:gridstatisticsforpolygons","/tmp/RESULT.tif","/path/municipalities.shp",False,False,True,False,True,False,False,False,0,None)
seems impossible to thematize on the basis of the Calculated column.
If saved as a new shapefile, it is OK. Possibly SAGA produces a wrong dbf? to new description:

#20819 (comment)

old description:

This file:
http://www.faunalia.eu/~paolo/qgis/result.zip
resulting from
processing.runalg("saga:gridstatisticsforpolygons","/tmp/RESULT.tif","/path/municipalities.shp",False,False,True,False,True,False,False,False,0,None)
seems impossible to thematize on the basis of the Calculated column.
If saved as a new shapefile, it is OK. Possibly SAGA produces a wrong dbf?

[qgib]

Author Name: Paolo Cavallini (@pcav)

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Still true in QGIS 3.

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• version was changed from master to 3.0.0

[Pedro-Murteira]

@pcav Hello, the link to the file is unreachable. Did you by any chance come across this issue in the more recent versions of QGIS?

[github-actions]

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[github-actions]

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