How to concatenate values of two fields with update cursor with ArcPy?

Question

I have a small block of code where I concatenate two date fields and use field calculator to calculate a the values of a third field. My date fields are ORIGDTDATE and ORIGDTTIME.

How can I change the block of code that is below to concatenate the fields if the value for the row in emergency_overdue is NULL?

import arcpy 
calcExpression = "!ORIGDTDATE!+\" \"+ !ORIGDTTIME!" 

arcpy.CalculateField_management(self.line_ticket_feature_class,"emergency_overdue",calcExpression,"PYTHON_9.3")

arcpy.CalculateField_management(self.poly_ticket_feature_class,"emergency_overdue",calcExpression,"PYTHON_9.3")

• FelixIP: Select by attribute, apply 1st, switch selection, apply second. I would replace it with da. Update Cursor, works much faster

Answer 1

You can create an update cursor with a where clause for only rows where emergency_overdue is null. The code below is a straight concatenation of the date and time fields, you may want to use a separator like "ORIGDTDATE" + ":" + "ORIGDTTIME".

with arcpy.da.UpdateCursor(self.line_ticket_feature_class, ["ORIGDTDATE", "ORIGDTTIME", "emergency_overdue"], "emergency_overdue IS NULL") as ucur:
 for row in ucur:
 row[2] = row[0] + row[1]
 ucur.updateRow(row)