update.da.cursor question about fields

[CW-GIS]

Hi everyone,

I'm stuck on a situation that I feel I'm making more complicated than it needs to be.

Situation: 

I have a database (700K records) that updates daily, I convert it to a spatial dataframe. I have a hosted feature layer (points) that updates daily. Right now I truncate and append the entire thing, but having it empty for a while isn't ideal.

I want to basically this:

• For each row in the database, search for the same 'key' in the hosted.
• If return clause = 1
• If any of the fields have different values, then update that field (or just the entire row)
• else 
• If return clause = 0
• insert cursor to insert that row
• else next row

Where I am getting confused is, does the da.cursor just use field position to insert values? row[19] will update the 19th column. But what if someone inserts a new column in the database, would everything get screwed up? Can I instead just match the field names with a field map?

[DanPatterson]

Fields are always added to the end.

If you want to get the field names prior to processing you can, and then produce an index to the name.

A simple example

fc0 = r'C:\\arcpro_npg\\Project_npg\\tests.gdb\\sq2'
from arcpy.da import SearchCursor
with SearchCursor(fc0, "*") as cursor:
    fld_names = cursor.fields
    n = len(fld_names)
    rpt = list(zip(range(0, n), fld_names))
    print(f"{rpt}")
    for row in cursor:
        print(f'{row[0]}')
        
[(0, 'OBJECTID'), (1, 'Shape'), (2, 'ids'), (3, 'CENTROID_X'),
 (4, 'CENTROID_Y'), (5, 'INSIDE_X'), (6, 'INSIDE_Y'),
 (7, 'PART_COUNT'), (8, 'PNT_COUNT'), (9, 'Sort_'),
 (10, 'Shape_Length'), (11, 'Shape_Area'), (12, 'Text')
, (13, 'Long_'), (14, 'Float_')]
1
2
3
4
5
6
9

There is limited information that you can get from the cursor

dir(cursor)
['__class__', '__delattr__', '__dir__', '__doc__', '__enter__', '__eq__',
 '__esri_toolinfo__', '__exit__', '__format__', '__ge__', '__getattribute__',
 '__getitem__', '__getstate__', '__gt__', '__hash__', '__init__',
 '__init_subclass__', '__iter__', '__le__', '__lt__', '__ne__', '__new__',
 '__next__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__',
 '__sizeof__', '__str__', '__subclasshook__',
 '_as_narray', '_dtype',
 'fields', 'next', 'reset']

# -- example
cursor._dtype
dtype([('OBJECTID', '<i4'), ('Shape', '<f8', (2,)), ('ids', '<i4'),
       ('CENTROID_X', '<f8'), ('CENTROID_Y', '<f8'), ('INSIDE_X', '<f8'),
       ('INSIDE_Y', '<f8'), ('PART_COUNT', '<f8'), ('PNT_COUNT', '<f8'),
       ('Sort_', '<i4'), ('Shape_Length', '<f8'), ('Shape_Area', '<f8'),
       ('Text', '<U20'), ('Long_', '<i4'), ('Float_', '<i4')])

the _as_narray can't be used if the fields includes the geometry, in such cases, you can use arcpy's FeatureClassToNumPyArray or TableToNumPyArray