[QGIS-Developer] QGIS3 plugin migration issue

[Nyall Dawson]

On 31 March 2018 at 14:06, André William <wss.andre at gmail.com> wrote:
> After some digging, I found that while the textShortHelp object is not
> directly available in the AlgorithmDialog class anymore, i was able to
> access it like this:
>>
>> shortHelpObj = dlg.findChild(QTextBrowser, 'textShortHelp')
>
> Is this the expected behavior?

None of this is in stable API, so can change between QGIS versions
(including within minor versions/patch releases).

Stable API for processing is:
- the classes within the core library (unless they are explicitly
marked as non-stable, e.g.  the modeler related classes)
- the base GUI "WidgetWrapper" class (NOT any of its subclasses)
- some methods from the processing namespace:
    - processing.algorithmHelp()
    - processing.run()
    - processing.runAndLoadResults()
    - processing.createAlgorithmDialog()
    - processing.execAlgorithmDialog()

So, in short, unfortunately this approach is always going to be
fragile. Better wrap it in a big try block! ;)

I gather you're trying to force the "help" panel to resize when the
dialog is opened. Is there a particular reason why you need to do
this?

Nyall


>
> André W.
>
> 2018-03-30 18:54 GMT-03:00 André William <wss.andre at gmail.com>:
>>
>> Hi all,
>>
>> I'm porting an existing Geoprocessing Algorithm plugin to QGIS 3 and I'm
>> having some trouble customizing the default dialog.
>> On QGIS 2.x the following code worked:
>>
>>> class TestAlgorithm(GeoAlgorithm):
>>>     INPUT = 'INPUT'
>>>     OUTPUT = 'OUTPUT'
>>>
>>>
>>>
>>>     def getCustomParametersDialog(self):
>>>         customDialog = AlgorithmDialog(self)
>>>         customDialog.textShortHelp.setFixedWidth(450)
>>>         return customDialog
>>
>>
>> On QGIS 3 however, the getCustomParametersDialog() method is gone. I
>> assumed it was replaced by the new createCustomParametersWidget(), but
>> unfortunately this method doesn't seem to get called by the parent class:
>>
>>>     def createCustomParametersWidget(self, parent):
>>>         customDialog = AlgorithmDialog(self)
>>>         customDialog.textShortHelp.setFixedWidth(450)
>>>         return customDialog
>>
>>
>> I also tried manually creating the dialog, but I get a message saying that
>> the 'AlgorithmDialog' object has no attribute 'textShortHelp'.
>>
>>> alg =
>>> QgsApplication.processingRegistry().algorithmById('test:testAlgorithm')
>>> dlg = AlgorithmDialog(alg)
>>> dlg.textShortHelp.setFixedWidth(450)
>>> dlg.show()
>>
>>
>> Any thoughts?
>>
>> Thanks in advance!
>> André
>
>
>
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