Calculate date difference between current date and previous date using Arcade with ArcGIS Pro

Question

I can't find the error in my code. I am trying to calculate the difference between the current date and a previous inspection date. I want the difference to be calculated in days. I am using ArcGIS Pro's field calculator for this task and am using Arcade code.

Field Calculator verifies the "Expression is valid" but when I run the code in Field Calculator for the 'Days_Since_Last_Inspection' field, the attribute table is not populated with any values and there are no errors... but the field still reads <Null> for each attribute in the 'Days_Since_Last_Inspection' field.

var startDate=Date($feature.Last_Inspection_Date)
var endDate=Now()
var result=DateDiff(endDate,startDate,'days')
return result

I have also tried adding a separate field to host todays date value. Therefore, the alternate code I have tried is:

var startDate=Date($feature.Last_Inspection_Date)
var endDate=Date($feature.Today_Date)
var result=DateDiff(endDate,startDate,'days')
return result

And field calculator is still not producing a calculated result between the two dates.

I am using ArcGIS Pro version 2.9.5, the 'Last_Inspection_Date' field is a date field formatted as yyyy-M-d, and the 'Days_Since_Last_Inspection' field is formatted as numeric with a Short data type. I have tried creating a text field thinking it might be the data type of the field preventing the calculation but that has not worked either. I have tried the similar questions asked on the topic and can't figure out why the code runs but does not produce the desired output.

Example Data:

Last Inspection Date	Days Since Inspection
2021-8-1	<Null>
2019-3-30	<Null>
2013-7-30	<Null>

Additional Information: I populated the 'Last_Inspection_Date' field with random dates using the following python code:

random_dates("2010-1-1", "2024-1-26")

def random_dates(start, end):
    import random
    from datetime import datetime
    frmt = '%Y-%m-%d'
    
    stime = time.mktime(time.strptime(start, frmt))
    etime = time.mktime(time.strptime(end, frmt))
    
    ptime = stime + random.random() * (etime - stime)
    random_date = datetime.fromtimestamp(time.mktime(time.localtime(ptime)))
    
    return random_date

Answer 1

The error was within the field calculation I performed for the 'Last_Inspection_Date' field:

random_dates("2010-1-1", "2024-1-26")

def random_dates(start, end):
    import random
    from datetime import datetime
    frmt = '%Y-%m-%d'
    
    stime = time.mktime(time.strptime(start, frmt))
    etime = time.mktime(time.strptime(end, frmt))
    
    ptime = stime + random.random() * (etime - stime)
    random_date = datetime.fromtimestamp(time.mktime(time.localtime(ptime)))
    
    return random_date

This code was including the local time within the date. I was thinking since the field was formatted for yyyy-M-d and since the code was formatted for %Y-%m-%d it would override the time series in my recycled code. However, from reading through technical details for datetime I realized the default format includes time, unless you specifically code for date only. The full code below generated a random date only. This then allowed me to use the original arcade code posted in the question above to calculate the difference between 'Last_Inspection_Date' and today's date in days.

def random_dates(start, end):
    import random
    from datetime import datetime
    frmt = '%Y-%m-%d'
    
    stime = datetime.strptime(start, frmt)
    etime = datetime.strptime(end, frmt)
    
    ptime = stime + random.random() * (etime - stime)
    random_date = ptime
    
    return random_date