Add CSV file, join to feature class, field calculate and save output using ArcPy?

Question

I am having some difficulty conceptualizing how the code should work for a custom ArcPy Script tool. Currently our work flow involves QA/QC and taking a csv file and joining it to a feature class. From there we calculate each field individually based on the values in the csv. This takes a tremendous amount of time. I am trying to automate this with a script. I am looking to create a tool allows one input (the csv file) and the tool will read the csv, join it to the feature class and then populates the fields automatically. I would also like to have some errors thrown if there is not able to join/calculate etc. I am not sure how this should flow.

import arcpy
import csv


def bringincsv(csv):
  with open(arcpy.GetParameterAsText(0), "rb") as csv:
   reader = csv.reader(csv, delimiter=",")
  next(reader):
  for row in reader:
   facilityid = str(row[0])
   diameter = double(row[1])
   hyperlink_cctv = string(row[2])
   hyperlink_rpt = string(row[3])


try:
 arcpy.env.workspace = 'CURRENT'
 inspection = arcpy.GetParameterAsText(0)
 arcpy.MakeTableView_management(in_table=inspection, out_view= 'Inspection')
 arcpy.AddJoin_management('Memphis.GIS.ssGravityMain', 'FACILITYID', 
 'Inspection', facilityid, 'KEEP_COMMON')


arcpy.CalculateField_management('Memphis.GIS.ssGravityMain', diameter, ##The 
csv files diameter)
arcpy.CalculateField_management('Memphis.GIS.ssGravityMain', hyperlink_cctv, 
 ##The csv files values)
 arcpy.CalculateField_management('Memphis.GIS.ssGravityMain', hyperlink_rpt, 
 ##The csv files values)

Answer 1

You can use a dictionary instead of joining them and the da.UpdateCursor instead of three field calculators. I am assuming that the first "column" in the csv is the field to match on.

import arcpy, csv

fc = r"C:\Test\Regions.shp"
idfield = 'IDFIELDNAME'
fields_to_update = ['F1','F2','F3'] #Add/remove fields here

csvfile = r"C:\Test\MoreData.csv"

with open(csvfile, mode='r',) as infile:
    reader = csv.reader(infile, delimiter=';') #Change delimiter to match your csv
    reader.next() #Skip header
    d = {r[0]:r[1:] for r in reader}

fields_to_update.append(idfield)
with arcpy.da.UpdateCursor(fc, fields_to_update) as cursor:
    for row in cursor:
        if row[-1] in d:
            row[0], row[1], row[2] = d[row[-1]] #Add/remove to match field count
            cursor.updateRow(row)
        else:
            print '{0} not found in csv, no update'.format(row[-1])

You can Place all this in a function with feature class and csv as inputs if you want to.