ArcPy updating fields from another table

Question

I'm trying to update missing values in one .shp from another .shp. I'm using SelectLayerByLocation to identify the properties which lie within the boundaries of a suburb and then using a UpdateCursor to update the properties list with the suburbs. The code below doesn't iterate through the list correctly so all I get is the first value from the initial SearchCursor updating the properties list.

fc_P = propertyDataset
fc_S = suburbsDataset
LOCALITYList = []
query = '"LOCALITY" =\'\''
field_P = ["LOCALITY"]
field_S = ["ADMINAREA"]

arcpy.MakeFeatureLayer_management(fc_S,"Suburbs_layer")
arcpy.MakeFeatureLayer_management(fc_P,"Properties_layer", query)

arcpy.SelectLayerByLocation_management("Properties_Layer", "WITHIN", 
"Suburbs_Layer")

with arcpy.da.SearchCursor("Suburbs_layer",field_S) as Srow:
    for row in Srow:
        Suburb = Srow[0]



with arcpy.da.UpdateCursor("Properties_layer", field_P) as Ucursor:
    for Urow in Ucursor:
        Urow[0] = Suburb
        Ucursor.updateRow(Urow)

del Ucursor
del Srow

Answer 1

I think you should try using spatial join instead. That way you dont need to iterate Select Layer By Location and multiple cursors. The output can be written to in_memory so that it not saved to disk and the output is used to create a dictionary of objectids and their suburb.

Try code below, I have no data to try it on so you might get some errors:

import arcpy

propfc = 'Properties'
subfc = 'Suburbs'
propfc_suburbfield = 'LOCALITY'
subfc_suburbfield = 'ADMINAREA'

#Create feature layer of properties with LOCALITY shorter than 2 charachters
sql = "CHAR_LENGTH({0})<2".format(arcpy.AddFieldDelimiters(propfc, propfc_suburbfield))
arcpy.MakeFeatureLayer_management(in_features=propfc, out_layer='proplyr', where_clause=sql)

#Spatial join suburbs to properties layer
tempspatjoin = r'in_memory\spatjoin'
arcpy.SpatialJoin_analysis(target_features='proplyr', join_features=subfc, out_feature_class=tempspatjoin, join_type='KEEP_COMMON',\
                           match_option='WITHIN')

#Create a dictionary of property objectids and what suburb they are in
updatedictionary = {k:v for k,v in arcpy.da.SearchCursor(tempspatjoin,['TARGET_FID',subfc_suburbfield])}

#Update proplyr with suburbs from dictionary
with arcpy.da.UpdateCursor('proplyr',['OID@',propfc_suburbfield]) as cursor:
    for row in cursor:
        if row[0] in updatedictionary: #If this rows oid is in dictionary
            row[1] = updatedictionary[row[0]] #Update with suburb
            cursor.updateRow(row)