singlepart to multipart broken in QGIS 2.0/master

[qgib]

Author Name: Giovanni Manghi (@gioman)
Original Redmine Issue: 8625
Affected QGIS version: master
Redmine category:processing/qgis

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tested on both Linux and Windows

An error has occured while executing Python code:

Traceback (most recent call last):
  File "C:\\OSGeo4W\\apps\\qgis-dev\\python\\plugins\\fTools\\tools\\doGeometry.py", line 324, in run
    success = self.single_to_multi()
  File "C:\\OSGeo4W\\apps\\qgis-dev\\python\\plugins\\fTools\\tools\\doGeometry.py", line 384, in single_to_multi
    if idVar.strip() == i.strip() or merge_all:
AttributeError: 'QPyNullVariant' object has no attribute 'strip'

Python version:
2.7.4 (default, Apr  6 2013, 19:54:46) [MSC v.1500 32 bit (Intel)]


QGIS version:
2.1.0-Master Master, 773e0d4

Python path: ['C:/OSGeo4W/apps/qgis-dev/./python/plugins\\\\sextante', 'C:/OSGeo4W/apps/qgis-dev/./python/plugins\\\\processing', 'C:/OSGeo4W/apps/qgis-dev/./python', u'C:\\\\Users\\\\giovanni/.qgis2/python', u'C:\\\\Users\\\\giovanni/.qgis2/python/plugins', 'C:/OSGeo4W/apps/qgis-dev/./python/plugins', 'C:\\\\Python27', 'C:\\\\mapnik-v2.2.0\\\\python\\\\2.7\\\\site-packages', 'C:\\\\OSGeo4W\\\\bin', 'C:\\\\OSGeo4W\\\\bin\\\\python27.zip', 'C:\\\\OSGeo4W\\\\apps\\\\Python27\\\\DLLs', 'C:\\\\OSGeo4W\\\\apps\\\\Python27\\\\lib', 'C:\\\\OSGeo4W\\\\apps\\\\Python27\\\\lib\\\\plat-win', 'C:\\\\OSGeo4W\\\\apps\\\\Python27\\\\lib\\\\lib-tk', 'C:\\\\OSGeo4W\\\\apps\\\\Python27', 'C:\\\\OSGeo4W\\\\apps\\\\Python27\\\\lib\\\\site-packages', 'C:\\\\OSGeo4W\\\\apps\\\\Python27\\\\lib\\\\site-packages\\\\PIL', 'C:\\\\OSGeo4W\\\\apps\\\\Python27\\\\lib\\\\site-packages\\\\win32', 'C:\\\\OSGeo4W\\\\apps\\\\Python27\\\\lib\\\\site-packages\\\\win32\\\\lib', 'C:\\\\OSGeo4W\\\\apps\\\\Python27\\\\lib\\\\site-packages\\\\Pythonwin', 'C:\\\\OSGeo4W\\\\apps\\\\Python27\\\\lib\\\\site-packages\\\\wx-2.8-msw-unicode', 'C:\\\\OSGeo4W\\\\apps\\\\qgis-dev\\\\python\\\\plugins\\\\fTools\\\\tools']

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• sample_data_ftools.zip (Salvatore Larosa)

[qgib]

Author Name: Andrey Isakov (@Andrey-VI)

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QGIS 2.0.1
Same error.
Vector -> Geometry Tools -> Singleparts to multipart

An error has occured while executing Python code:

Traceback (most recent call last):
  File "/usr/share/qgis/python/plugins/fTools/tools/doGeometry.py", line 325, in run
    success = self.single_to_multi()
  File "/usr/share/qgis/python/plugins/fTools/tools/doGeometry.py", line 385, in single_to_multi
    if idVar.strip() == i.strip() or merge_all:
AttributeError: 'float' object has no attribute 'strip'

Python version:
2.7.5+ (default, Sep 17 2013, 15:33:59) 
[GCC 4.8.1]


QGIS version:
2.0.1-Dufour Dufour, exported

Python path: ['/usr/share/qgis/python/plugins/processing', '/usr/share/qgis/python', '/home/andrey/.qgis2/python', '/home/andrey/.qgis2/python/plugins', '/usr/share/qgis/python/plugins', '/usr/lib/python2.7', '/usr/lib/python2.7/plat-x86_64-linux-gnu', '/usr/lib/python2.7/lib-tk', '/usr/lib/python2.7/lib-old', '/usr/lib/python2.7/lib-dynload', '/usr/local/lib/python2.7/dist-packages', '/usr/lib/python2.7/dist-packages', '/usr/lib/python2.7/dist-packages/PIL', '/usr/lib/python2.7/dist-packages/gtk-2.0', '/usr/lib/pymodules/python2.7', '/home/andrey/.qgis2/python/plugins/mmqgis/forms', '/usr/share/qgis/python/plugins/fTools/tools'] 

[qgib]

Author Name: Salvatore Larosa (@slarosa)

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This seems to happen when the layer has @null@ attribute values, I had proposed a "patch":#783 (comment) which
has not been applied because this commit cba57fa by Matthias solved the issue with @null@ values reported in the same PR, but I am still getting a QPyNullVariant error here.

Can anyone test the tool with the attached sample data?

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• 6625 was configured as sample_data_ftools.zip
• tag was configured as easy

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• sample_data_ftools.zip (Salvatore Larosa)

[qgib]

Author Name: Giovanni Manghi (@gioman)

---

Salvatore Larosa wrote:

but I am still getting a QPyNullVariant error here.

confirmed

An error has occured while executing Python code:

Traceback (most recent call last):
  File "/usr/share/qgis/python/plugins/fTools/tools/doGeometry.py", line 326, in run
    success = self.single_to_multi()
  File "/usr/share/qgis/python/plugins/fTools/tools/doGeometry.py", line 386, in single_to_multi
    if idVar.strip() == i.strip() or merge_all:
AttributeError: 'QPyNullVariant' object has no attribute 'strip'

[qgib]

Author Name: Matthias Kuhn (@m-kuhn)

---

Can confirm.

Some comments:

• Just to be sure: What is the result expected to be? Should NULL values be grouped? From a database perspective it seems like "yes, but it is an edge-case":http://en.wikipedia.org/wiki/Null_%28SQL%29#When_two_nulls_are_equal:_grouping.2C_sorting.2C_and_some_set_operations
• What about the option of removing the .strip() altogether? From a database perspective this would not be used (" a " is distinct from "a") but I can perfectly see that it may help new users to cover their data inconsistencies. What about making it an option, checked by default?
• Your patch will lead to conflicts, when the user actually has the string u"NULL" as a value in his attributes. For my part, I'd like to get away from this substitute strings as good as possible.

[qgib]

Author Name: Giovanni Manghi (@gioman)

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• Just to be sure: What is the result expected to be? Should NULL values be grouped? From a database perspective it seems like "yes, but it is an edge-case":http://en.wikipedia.org/wiki/Null_%28SQL%29#When_two_nulls_are_equal:_grouping.2C_sorting.2C_and_some_set_operations

from a user point of view I would say "yes", group them. But if it is hard then a warning message (and ask to fill properly the null records) would be enough.

[qgib]

Author Name: Andrey Isakov (@Andrey-VI)

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Matthias Kuhn wrote:

• Just to be sure: What is the result expected to be? Should NULL values be grouped? From a database perspective it seems like "yes, but it is an edge-case":http://en.wikipedia.org/wiki/Null_%28SQL%29#When_two_nulls_are_equal:_grouping.2C_sorting.2C_and_some_set_operations

In some cases YES, in other — NO. So, I think we need an additional check-box for NULL values.

[qgib]

Author Name: Matthias Kuhn (@m-kuhn)

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Fixed in changeset "e4f410b589c43ce346930fd2523b815741c6257a".

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• status_id was changed from Open to Closed

[qgib]

Author Name: Giovanni Manghi (@gioman)

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The "ftools" category is being removed from the tracker, changing the category of this ticket to "Processing/QGIS" to not leave the category orphaned.