OGR processing of scratch layers doesn't work

[qgib]

Author Name: Tobias Wendorff (Tobias Wendorff)
Original Redmine Issue: 17287
Affected QGIS version: 2.18.13
Redmine category:processing/ogr
Assignee: Giovanni Manghi

---

I've created a point on a scratch layer (EPSG:4326) and want to create an ogr2ogr buffer using "processing".
The result is an error, as you can see on the animated gif attached.

---

• qgis3_bug_gdal_scratch.gif (Tobias Wendorff)

[qgib]

Author Name: Tobias Wendorff (Tobias Wendorff)

---

Copy of the error message:

Algorithm 'Buffer vectors' starting...
Input parameters:
{ 'INPUT' : 'Point?crs=EPSG:4326&uid={fb3f5b3a-77ef-461f-876b-8e13f9e20cf4}', 'GEOMETRY' : 'geometry', 'DISTANCE' : 10, 'FIELD' : '', 'DISSOLVE' : False, 'EXPLODE_COLLECTIONS' : False, 'OPTIONS' : '', 'OUTPUT' : 'C:/Users/test/AppData/Local/Temp/processing_b3eeb99e5a0c4e5f990f7c7b7d49a8d6/beb3eb9ca76546efa9be8f327ce40fa4/OUTPUT.shp' }

GDAL command:
ogr2ogr "C:/Users/test/AppData/Local/Temp/processing_b3eeb99e5a0c4e5f990f7c7b7d49a8d6/beb3eb9ca76546efa9be8f327ce40fa4/OUTPUT.shp" C:/Users/test/AppData/Local/Temp/processing_b3eeb99e5a0c4e5f990f7c7b7d49a8d6/0db7b207ed4a459799cd887f39ac6a98/INPUT.shp -dialect sqlite -sql "SELECT ST_Union(ST_Buffer(geometry, 10.0)) AS geometry, FROM 'INPUT'" -f "ESRI Shapefile"
GDAL command output:
ERROR 1: In ExecuteSQL(): sqlite3_prepare_v2(SELECT ST_Union(ST_Buffer(geometry, 10.0)) AS geometry, FROM 'INPUT'): 
near "FROM": syntax error 
Execution completed in 0.64 seconds
Results:
{'OUTPUT': <QgsProcessingOutputLayerDefinition {'sink':C:/Users/test/AppData/Local/Temp/processing_b3eeb99e5a0c4e5f990f7c7b7d49a8d6/beb3eb9ca76546efa9be8f327ce40fa4/OUTPUT.shp, 'createOptions': {'fileEncoding': 'System'}}>}

Loading resulting layers
Algorithm 'Buffer vectors' finished

Seems like the comma is wrong :)

[qgib]

Author Name: Tobias Wendorff (Tobias Wendorff)

---

Argh... of course the comma is wrong. It expects a field! But this isn't needed...

[qgib]

Author Name: Nyall Dawson (@nyalldawson)

---

Does it work correctly if you add a field to the memory layer?

I suspect this issue isn't related to the use of a memory layer, but rather that the algorithms don't work correctly with layers with no fields. In which case it's likely also an issue in 2.x

---

• status_id was changed from Open to Feedback

[qgib]

Author Name: Tobias Wendorff (Tobias Wendorff)

---

Nyall Dawson wrote:

Does it work correctly if you add a field to the memory layer?

Yes it does.

I suspect this issue isn't related to the use of a memory layer, but rather that the algorithms don't work correctly with layers with no fields. In which case it's likely also an issue in 2.x

It didn't work in 2.x:

cannot concatenate 'str' and 'NoneType' objects See log for more details

But it should work in ogr2ogr! Without the comma, I'm getting the correct result.

Could you perhaps add the comma only, if fields.length > 0 ?

[qgib]

Author Name: Nyall Dawson (@nyalldawson)

---

• version was changed from master to 2.18.13

[qgib]

Author Name: Giovanni Manghi (@gioman)

---

isn't this duplicate of #24430 ?

[qgib]

Author Name: Tobias Wendorff (Tobias Wendorff)

---

Giovanni Manghi wrote:

isn't this duplicate of #24430 ?

No, I'm using the core function and my processing doesn't start at all, since the OGR commandline breaks.

[qgib]

Author Name: Giovanni Manghi (@gioman)

---

• status_id was changed from Feedback to Open
• assigned_to_id was changed from Victor Olaya to Giovanni Manghi

[qgib]

Author Name: Giovanni Manghi (@gioman)

---

• subject was changed from QGIS3: OGR processing of scratch layers doesn't work to OGR processing of scratch layers doesn't work

[qgib]

Author Name: Giovanni Manghi (@gioman)

---

I have a fix in the works for master/qgis3 (for the buffer tool at least), for qgis2 I really think that the issue is the same of #24430 : in Processing scratch layers (with or without fields) are not supported.

[qgib]

Author Name: Giovanni Manghi (@gioman)

---

A better and more complete fix for master #5436

[qgib]

Author Name: Alexander Bruy (@alexbruy)

---

Applied in changeset 4a51c40.

---

• done_ratio was changed from 0 to 100
• status_id was changed from Open to Closed