Merge Selected Features - warn user in advance when merged geometry type does not match layer geometry type

[qgib]

Author Name: Peteris Bruns (@peterisb)
Original Redmine Issue: 16974

Redmine category:editing
Assignee: Giovanni Manghi

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In case when merged geometry type does not match layer geometry type warning should appear already in Merge Selected Features dialogue, not after several 10 object merge on Save receive surprise message. This makes bad user experience since in message is not possible to identify wrong geometry/feature.

Solution would be to warn user already in Merge Selected Features dialogue in case when merged feature final geometry type is not equal to target layer geometry type.

As in example.png

• ShapeFile/PostGIS layer with geometry type LineString.
• several Linestring features.
• try to merge 2 features without common start/end points, result is MultiLineString (in dialogue should be as minimum warning, probably disabled OK button while resulting geometry is not compatible with target layer geometry type)

In cases when user has merged several features, a+b=a Linestring, c+d=c Multilinestring on save both changes from QGIS is received message
"Could not commit changes to layer LineString Layer Errors: ERROR: 2 feature(s) not added - geometry type is not compatible with the current layer." but this message does not help to identify wrong feature and fix it. Usually user cancels edit and loses all work without save and repeats feature merge again while faces the problematic features and fixes.

Related to issues #23663 #24691

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• example.png (Peteris Bruns)
• vokoscreen-2017-08-08_21-47-26.mkv (Peteris Bruns)
• bug_examples.gpkg (Peteris Bruns)

[qgib]

Author Name: Giovanni Manghi (@gioman)

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Actually this WAS the way QGIS used to work.

In fact in QGIS 2.14 trying to create a multi part geometry in a non multi part layer resulted in CLEAR message BEFORE the user clicked on "save edits".

See #23663 (comment)

if this not fixed as the above ticket suggest than #23663 must be reopened.

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• easy_fix was changed from 1 to 0
• status_id was changed from Open to Feedback

[qgib]

Author Name: Peteris Bruns (@peterisb)

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Thanks for pointing #23663 (comment), in QGIS 2.18.11 I can't see message and behavior as described in #23663 (comment).

Testing with QGIS 2.18.11, linestring layer (GPKG, ESRI ShapeFile, memory layer). Attached data example and video.

First merges is OK, the 2nd is buggy.

In this case is visually clear wich merge is buggy, but if user has made several, 10 and more, similar merge actions before save, then from save message is impossible to identify where is bug. Cancel all edits and start again.

So far seems that #23663 must be reopened.

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• 11321 was configured as bug_examples.gpkg
• 11320 was configured as vokoscreen-2017-08-08_21-47-26.mkv

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• bug_examples.gpkg (Peteris Bruns)
• vokoscreen-2017-08-08_21-47-26.mkv (Peteris Bruns)

[qgib]

Author Name: Peteris Bruns (@peterisb)

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#23663 must be reopened.

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• assigned_to_id was configured as Giovanni Manghi

[qgib]

Author Name: Giovanni Manghi (@gioman)

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done.

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• status_id was changed from Feedback to Closed
• resolution was changed from to duplicate