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I need to count how many times I executed a Pyhthon script in QGIS and I would like to do so by using a project variable as counter. However, I can only create them as string, thus I can't perform mathematical operations with them (count = count + 1).
Is it possible to change their type to integer or to create a counter using pygqis?
prj = QgsProject.instance()
QgsExpressionContextUtils.setProjectVariable(prj,'counter',"0")
counter=int(QgsExpressionContextUtils.projectScope(prj).variable('counter'))
QgsExpressionContextUtils.setProjectVariable(prj,'counter',counter+1)
The first line finds the current project (needed for QGIS >= 3). The next line initializes to zero, the last 2 lines read and set the counter incremented by one.
str conversion instead of what I suspect is a coercion somewhere to string in your last line. But yay it works!
Jun 24, 2019 at 17:37
Convert between strings and integers with str and int:
>>> x = "1"
>>> str(int(x) + 1)
'2'
>>>
So you'll be storing the string representation of your count as a string. Convert back to int when you retrieve it, and convert back to string when you store it.
Beware of errors if converting non-valid strings to ints:
>>> int("s")
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
ValueError: invalid literal for int() with base 10: 's'
