Advanced python labeling in ArcMap - working with null values

Question

I'm trying to label certain features using a specific field (osm_name_58_en). However, when this field is null, I want to label the feature with (som_english_32_name). If both are null then I want to label with the (amenity) field.

This is the code I'm trying but I'm not getting anything in return. Maybe I'm completely out to left field? I'm a python and advanced labeling newbie.

def FindLabel ( [amenity], [osm_english_32_name], [osm_name_58_en] ):
    if not ([osm_name_58_en] is None):
        return [osm_name_58_en]
    elif ([osm_name_58_en] is None and not([osm_english_32_name] is None)):
        return [osm_english_32_name] + '\n' + [amenity] 
    else:
        return [amenity];

Answer 1

The Correct form of your code is :

def FindLabel ( [amenity], [osm_english_32_name], [osm_name_58_en] ):
    if not ([osm_name_58_en] is None):
        return [osm_name_58_en]
    elif not([osm_english_32_name] is None):
        return [osm_english_32_name] + '\n' + [amenity] 
    else:
        return [amenity]

The semicolon in the last line is removed. and your elif statement is repaired

Answer 2

The code presented in your question doesn't match what is asked for in the question.

"I'm trying to label certain features using a specific field (osm_name_58_en). However, when this field is null, I want to label the feature with (som_english_32_name). If both are null then I want to label with the (amenity) field."

This sentence implies that you only want one field for any given label.

If this is the case the following code will do what you want.

def FindLabel ( [amenity], [osm_english_32_name], [osm_name_58_en] ):
    if not [osm_name_58_en] is None:
        return [osm_name_58_en]
    elif not [osm_english_32_name] is None:
        return [osm_english_32_name]
    elif not [amenity] is None:
        return [amenity]  

Now, if you want to get the code in the question working correctly here is what you need.

def FindLabel ( [amenity], [osm_english_32_name], [osm_name_58_en] ):
    if not ([osm_name_58_en] is None):
        return [osm_name_58_en]
    elif not([osm_english_32_name] is None):
        return [osm_english_32_name] + '\n' + [amenity] 
    else:
        return [amenity]