[QGIS-Developer] Clear exception messages in algorithms

Wed May 29 03:43:27 PDT 2019

Dear list,

I'm currently developing a plugin that adds algorithms that query an API.
There are some very clear issues that may arise, such as hitting an API
quota limit.

However, I couldn't find a way to provide clear error message to the user.

This is what I have in my processAlgorithm(...) method :

if limit_reached:
feedback.reportError("API usage limit reached", fatalError=True)
raise QgsProcessingException("API usage limit warning")

It works well, but the error is hidden in the middle of a potentially long
trace (see below) that is so cryptic for the typical user that he will miss
the important message (which is "API usage limit reached").

I tried to play a bit around with things like `raise QgsException(...) from
None` or other things, but could find a way to provide better output for
the user. And since it's from an algorithm, it's not possible to use
iface.pushMessage() or any other UI mean to do so...

Any pointer would be greatly appreciated !

Cheers,

Olivier

Example output log :

Processing algorithm…

Algorithm 'Time Map - Simple' starting…

Input parameters:

{ 'INPUT_SEARCHES' :
'memory?geometry=Point&crs=EPSG:4326&field=full_id:string(0,0)&field=osm_id:string(0,0)&field=osm_type:string(0,0)&field=amenity:string(0,0)&field=name:string(0,0)&field=cuisine:string(0,0)&field=addr:housenumber:string(0,0)&field=addr:postcode:string(0,0)&field=addr:street:string(0,0)&field=diet:gluten_free:string(0,0)&field=diet:vegetarian:string(0,0)&field=phone:string(0,0)&field=wheelchair:string(0,0)&field=addr:city:string(0,0)&field=fhrs:id:string(0,0)&field=source:addr:string(0,0)&field=alt_name:string(0,0)&field=fhrs:authority:string(0,0)&field=fhrs:inspectiondate:string(0,0)&field=fhrs:rating:string(0,0)&field=addr:housename:string(0,0)&field=addr:unit:string(0,0)&field=dontimport:fhrs:addrline1:string(0,0)&field=dontimport:fhrs:addrline2:string(0,0)&field=dontimport:fhrs:businesstype:string(0,0)&field=opening_hours:string(0,0)&field=email:string(0,0)&field=website:string(0,0)&field=contact:phone:string(0,0)&field=wheelchair:description:string(0,0)&field=toilets:wheelchair:string(0,0)&field=toilets:string(0,0)&field=toilets:access:string(0,0)&field=opening_hours:url:string(0,0)&field=takeaway:string(0,0)&field=fhrs:confidence_management:string(0,0)&field=fhrs:hygiene:string(0,0)&field=fhrs:local_authority_id:string(0,0)&field=fhrs:structural:string(0,0)&field=outdoor_seating:string(0,0)&field=source:postcode:string(0,0)&field=wikidata:string(0,0)&field=payment:american_express:string(0,0)&field=old_name:string(0,0)&field=source:addr:postcode:string(0,0)&field=diet:raw:string(0,0)&field=diet:vegan:string(0,0)&field=facebook:string(0,0)&field=warning:string(0,0)&field=currency:XLT:string(0,0)&field=payment:cash:XLT-BXTP:string(0,0)&field=payment:text:XLT-BXTP:string(0,0)&field=postal_code:string(0,0)&field=addr:country:string(0,0)&field=brand:string(0,0)&field=brand:wikidata:string(0,0)&field=brand:wikipedia:string(0,0)&field=contact:website:string(0,0)&field=capacity:string(0,0)&field=operator:string(0,0)&field=smoking:string(0,0)&field=level:string(0,0)&field=postcode:string(0,0)&field=layer:string(0,0)&field=delivery:string(0,0)&field=contact:email:string(0,0)&field=addr:floor:string(0,0)&field=description:floor:string(0,0)&field=old_fhrs:id:string(0,0)&field=old_fhrs:local_authority_id:string(0,0)&field=addr:suburb:string(0,0)&field=wifi:string(0,0)&field=drive_in:string(0,0)&field=microbrewery:string(0,0)&field=branch:string(0,0)&field=tourism:string(0,0)&field=note:name:ko:string(0,0)&field=wikipedia:string(0,0)&field=name:en:string(0,0)&field=url:string(0,0)&field=name:zh:string(0,0)&field=old_cuisine:string(0,0)&field=diet:pescetarian:string(0,0)&field=seats:string(0,0)&field=bar:string(0,0)&field=type:string(0,0)&field=former_name:string(0,0)&field=food:string(0,0)&field=disused:string(0,0)&field=operator:wikidata:string(0,0)&field=disused:name:string(0,0)&field=addr:place:string(0,0)&field=contact:fax:string(0,0)&field=fax:string(0,0)&field=note:name:en:string(0,0)&field=note:name:zh:string(0,0)&field=alcohol:string(0,0)&field=entrance:string(0,0)&field=internet_access:fee:string(0,0)&field=brewery:string(0,0)&field=note:name:string(0,0)&field=instagram:string(0,0)&field=twitter:string(0,0)&field=building:level:string(0,0)&field=internet_access:string(0,0)&field=description:string(0,0)&field=trendy:string(0,0)&field=colour:string(0,0)&field=erected_by:string(0,0)&field=historic:string(0,0)&field=inscription:string(0,0)&field=memorial:string(0,0)&field=openplaques:id:string(0,0)&field=scheme:string(0,0)&field=addr:full:string(0,0)&field=number:string(0,0)&field=contact:twitter:string(0,0)&field=name:es:string(0,0)&field=name:gl:string(0,0)&field=uri:string(0,0)&field=indoor_seating:string(0,0)&field=music:string(0,0)&field=product:string(0,0)&field=contact:facebook:string(0,0)&field=ref:NPLG:UPRN:1:string(0,0)&field=drink:coffee:string(0,0)&field=drink:soft_drink:string(0,0)&field=drink:tea:string(0,0)&field=source:name:string(0,0)&field=wikimedia_commons:string(0,0)&field=access:string(0,0)&field=barrier:string(0,0)&field=building:string(0,0)&field=payment:bitcoin:string(0,0)&field=start_date:string(0,0)&field=shop:units:string(0,0)&field=source:position:string(0,0)&field=survey:date:string(0,0)&field=payment:cash:string(0,0)&field=payment:credit_cards:string(0,0)&field=payment:debit_cards:string(0,0)&field=camera:mount:string(0,0)&field=camera:type:string(0,0)&field=man_made:string(0,0)&field=surveillance:string(0,0)&field=surveillance:type:string(0,0)&field=surveillance:zone:string(0,0)&field=disused:amenity:string(0,0)&field=shop:string(0,0)&field=checkfirst:suggested:name:string(0,0)&field=source:date:string(0,0)&field=addr:interpolation:string(0,0)&field=diet:halal:string(0,0)&field=note_1:string(0,0)&field=designation:string(0,0)&field=addr:flat:string(0,0)&field=addr:flats:string(0,0)&field=organic:string(0,0)&field=memorial:type:string(0,0)&field=max_level:string(0,0)&field=min_level:string(0,0)&field=fhrs:name:string(0,0)&field=diet:string(0,0)&field=construction:string(0,0)&field=old_amenity:string(0,0)&field=happycow:id:string(0,0)&field=drive_through:string(0,0)&field=contact:instagram:string(0,0)&field=payment:mastercard:string(0,0)&field=payment:visa:string(0,0)&field=drink:wine:string(0,0)&field=payment:jcb:string(0,0)&field=contact:google_plus:string(0,0)&field=name:gsw:string(0,0)&field=drink:cider:string(0,0)&field=reservation:string(0,0)&field=name:ru:string(0,0)&field=name:nl:string(0,0)&field=name:lt:string(0,0)&field=name:ja:string(0,0)&field=name:ar:string(0,0)&field=name:it:string(0,0)&field=website:en:string(0,0)&field=name:pt:string(0,0)&field=amenity_1:string(0,0)&field=self_service:string(0,0)&field=highway:string(0,0)&field=lamp_mount:string(0,0)&field=name:pl:string(0,0)&field=stars:string(0,0)&field=drink:beer:string(0,0)&field=drink:lemonade:string(0,0)&field=drink:water:string(0,0)&field=breakfast:string(0,0)&field=drink:natural_wine:string(0,0)&field=name:ro:string(0,0)&field=drink:cola:string(0,0)&field=disused:shop:string(0,0)&field=not:addr:postcode:string(0,0)&field=source:addr:housenumber:string(0,0)&field=camera:direction:string(0,0)&field=real_ale:string(0,0)&field=not:addr:street:string(0,0)&field=baby_change:string(0,0)&field=name:fr:string(0,0)&field=automatic_door:string(0,0)&field=door:string(0,0)&field=serves_cars:bool(0,0)&field=is_drive_through:bool(0,0)&uid={98191443-a039-467a-a0c6-4dbfb08707cf}',
'INPUT_SEARCH_TYPE' : 0, 'INPUT_TIME' : '2019-05-29T12:00:00',
'INPUT_TRAVEL_TIME' : 15, 'INPUT_TRNSPT_TYPE' : 0, 'OUTPUT' : 'memory:',
'OUTPUT_RESULT_TYPE' : 0 }

Starting TimeMapSimpleAlgorithm...

Calling subcommand with following parameters...

{'INPUT_DEPARTURE_SEARCHES': <qgis._core.QgsVectorLayer object at
0x00000249EB1ADCA8>, 'INPUT_DEPARTURE_TRNSPT_TYPE': "'cycling'",
'INPUT_DEPARTURE_TIME': "'2019-05-29T12:00:00'", 'OUTPUT_RESULT_TYPE': 0,
'OUTPUT': 'memory:results', 'INPUT_DEPARTURE_TRAVEL_TIME': '900',
'INPUT_DEPARTURE_TRNSPT_WALKING_TIME': '900'}

Starting TimeMapAlgorithm...

Checking API limit warnings...

API usage limit reached !

Traceback (most recent call last):
File
"C:/Users/Olivier/AppData/Roaming/QGIS/QGIS3\profiles\default/python/plugins\travel_time_platform_plugin\algorithms\advanced.py",
line 383, in processAlgorithm
slices = self.processAlgorithmGetSlices(parameters, context, feedback)
File
"C:/Users/Olivier/AppData/Roaming/QGIS/QGIS3\profiles\default/python/plugins\travel_time_platform_plugin\algorithms\advanced.py",
line 234, in processAlgorithmGetSlices
self.processAlgorithmEnforceLimit(len(slices), parameters, context,
feedback)
File
"C:/Users/Olivier/AppData/Roaming/QGIS/QGIS3\profiles\default/python/plugins\travel_time_platform_plugin\algorithms\base.py",
line 245, in processAlgorithmEnforceLimit
raise QgsProcessingException("API usage limit reached ") from None
_core.QgsProcessingException: API usage limit reached

There were errors executing the algorithm.

Traceback (most recent call last):
File
"C:/Users/Olivier/AppData/Roaming/QGIS/QGIS3\profiles\default/python/plugins\travel_time_platform_plugin\algorithms\simple.py",
line 111, in processAlgorithm
sub_id, sub_parameters, context=context, feedback=feedback
File
"C:/OSGEO4~1/apps/qgis-ltr/./python/plugins\processing\tools\general.py",
line 105, in run
return Processing.runAlgorithm(algOrName, parameters, onFinish, feedback,
context)
File
"C:/OSGEO4~1/apps/qgis-ltr/./python/plugins\processing\core\Processing.py",
line 183, in runAlgorithm
raise QgsProcessingException(msg)
_core.QgsProcessingException: There were errors executing the algorithm.

Execution failed after 0.16 seconds

Loading resulting layers

Algorithm 'Time Map - Simple' finished
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