PythonCaller input loop

I suspect this question would be more suitable in a Python forum.

Anyway, it's difficult to help unless you post the whole code and tell us precisely what you want to achieve.

def input(self,feature):

	...

	myAnswerField = [('Echelle1', None), ('Echelle2', None)] 	if '01' in feature.getAttribute('id_reseau'):
            scale1 = feature.getAttribute('echellesortieplanprincipal')
            myAnswerFields.remove(('Echelle1', None))
            myAnswerFields.append(('Echelle1', scale1))
        if '02' in feature.getAttribute('id_reseau'):
            scale2 = feature.getAttribute('echellesortieplanprincipal')
            myAnswerFields.remove(('Echelle2', None))
            myAnswerFields.append(('Echelle2', scale2))

 

with this database : 

 

I thought it was a PythonCaller problem actually. Maybe I misunderstood.

 

The way the PythonCaller works is pretty simple and it is coherent with the way Python (and most OOP languagues) work in this type of pattern:

 

 

• Before the first feature arrives: call __init__() once
• For each feature: call input() once per feature
• After the last feature has passed: call close() once

You may want to read up a bit on Python objects and particulary on scope, e.g. here. I agree with @verdoodtdries that it looks like a scoping error.

 

 

I do not quite understand what you really want to achieve, but I suspect you want to make myAnswerField an object instance variable (rather than a local variable, as it is now). You can do this by initalizing myAnswerField in __init__() and prefixing it with "self." whenever you reference it.

 

 

As it is you are effectively resetting (redefining) myAnswerField for every incoming feature, that may not be what you want?

The way the PythonCaller works is pretty simple and it is coherent with the way Python (and most OOP languagues) work in this type of pattern:

 

 

• Before the first feature arrives: call __init__() once
• For each feature: call input() once per feature
• After the last feature has passed: call close() once

You may want to read up a bit on Python objects and particulary on scope, e.g. here. I agree with @verdoodtdries that it looks like a scoping error.

 

 

I do not quite understand what you really want to achieve, but I suspect you want to make myAnswerField an object instance variable (rather than a local variable, as it is now). You can do this by initalizing myAnswerField in __init__() and prefixing it with "self." whenever you reference it.

 

 

As it is you are effectively resetting (redefining) myAnswerField for every incoming feature, that may not be what you want?

Ok, it's seems that I should have just one feature in the input instead of 2. A colleague of mine helped me on that. So problem solved.

 

Thanks anyway. I have a better understanding of the PythonCller thanks to you.