Making multiple fields NULL using Python in ArcGIS?

Question

I have a repetitive task here at work. It requires that I make multiple fields NULL as I update the geodatabase. Is there a script I can write that I can input the fields and the feature class. Then make all those fields NULL. This script must not make everything NULL in the feature class, only the fields designated. import arcpy

fc = "N:\Updates\CarsonCityNV\CarsonCityNV.gdb\J_POC_S_Studies_Ln"
with arcpy.da.UpdateCursor(fc, ("C1_GAGE", "C2_DISCH", "C3_MODEL", "C4_FCSTR", "C5_CHANN", "C6_HSTR, "C7_SCOUR", "S1_REGEQ", "S2_REPLO", "S3_IMPAR", "S4_HSTR", "S5_CHIMP", "S6_TOPO", "S7_VEGLU", "S9_HWMS", "S10_REGEQ", "CE_TOTAL", "SE_TOTAL", "A1_TOPO", "A2_HYDRO", "A3_IMPAR", "A4_TECH", "A5_FOAPASS")) as cursor:
 for row in cursor:
 row[0] = None
 row[1] = None
 row[2] = None
 row[3] = None
 row[4] = None
 row[5] = None
 row[6] = None
 row[7] = None
 row[8] = None
 row[9] = None
 row[10] = None
 row[11] = None
 row[12] = None
 row[13] = None
 row[14] = None
 row[15] = None
 row[16] = None
 row[17] = None
 row[18] = None
 row[19] = None
 row[20] = None
 row[21] = None
 row[22] = None
 cursor.updateRow(row)

I'm getting a parsing error on line 5.

Answer 1

Just change the path of fc to your feature class, and change YourField to the field name.

import arcpy
fc = "C:\\Temp\\Data.gdb\\FeatureClass"
with arcpy.da.UpdateCursor(fc, ("YourField")) as cursor:
 for row in cursor:
 row[0] = None
 cursor.updateRow(row)

To do multiple fields, just add another field to the tuple and set the row equal to None:

import arcpy
fc = "C:\\Temp\\Data.gdb\\FeatureClass"
with arcpy.da.UpdateCursor(fc, ("YourField", "YourField2")) as cursor:
 for row in cursor:
 row[0] = None
 row[1] = None
 cursor.updateRow(row)

• Christopher Harrod: You are awesome man, just saved me loads of time. I will try it out. Can I also use this to populate fields with something other than null?
• ianbroad: @ChristopherHarrod yeah, instead of setting the row equal to None, just set it to whatever value you want that fits the field type. If it's a text field, you need to enclose the text in quotes, such as row[0] = "This is my text"
• Christopher Harrod: If I have a thousand rows, will I have to declare each one? i.e. row [0] row [1] row [2]... and so on.
• ianbroad: No, row[0] is actually identifying a field in the tuple. In the example above, row[0] is "YourField", and row[1] is "YourField2". So, it is populating None for every row in each field that you designate - this might explain it better: gis.stackexchange.com/questions/158958/…
• Christopher Harrod: Ok, great, I will give it a go.