Concatenate multiple string / text fields some of which may have NULL values ArcGIS

Question

I am trying to repeat the behavior of this code from the ESRI website.

I want to replicate the output example in ALL_Type field, so that it concatenates a field but it deals (ignores) any that have NULL values.

Unfortunately this example no longer works at 10.2.2 because all example of NULL return a "None" text. Instead I just want a blank to show.

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And here is the code.

 "*args" allows this routine to accept any number of field values.
# the values are passed as a Python tuple, essentially a
# non-editable list
#
def concat(*args):
 # Initialize the return value to an empty string,
 # then set the separator character
 #
 retval = ""
 sep = "_"
 # For each value passed in...
 #
 for t in args:
 # Convert to a string (this catches any numbers),
 # then remove leading and trailing blanks
 #
 s = str(t).strip()
 # Add the field value to the return value, using the separator
 # defined above
 #
 if s <> '':
 retval += sep + s
 # Strip of any leading separators before returning the value
 #
 return retval.lstrip(sep)

• Erica: Try if s <> '' and s is not None:
• user21053: Thanks I just tried your suggestion, i also tried the following but none of them worked if (s <> '' and s is not None): if s <> '' and s is not "None":
• Erica: How about conditional if t is not None: before it converts t to a string s = str(t).strip() --- or if s <>'' and s <> 'None':
• user21053: yep that worked now with the 'None' - it needed the quotations, as it is text - THANKS.

Answer 1

I think this should do what you want:

def concat(*args):
 sep = "_"
 nonnull_args = [str(arg).strip() for arg in args if arg] # Filter NULLs
 good_args = [arg for arg in nonnull_args if arg] # Filter blanks
 retval = sep.join(good_args)
 return retval

The args just get passed through a couple filters and joined by sep at the end.

• user21053: just tested this and it works as well -many thanks!