Joining one field from multiple feature classes to another feature class

Question

I've got 19 feature classes, with a single field in each one that I am interested in. I want to pull that field from each one (index 63 on each feature class), and join those fields to a single feature class (inDWR). In the workspace, I've got numerous fc's, and the 19 aforementioned feature classes all end with 'EVTP' in their file name. So, I've distilled a list accordingly (extractList):

import arcpy
from arcpy import env
from arcpy.sa import *
env.workspace = 'C:\\LaPlata\\LaPlataFmTops.gdb'
inDWR = env.workspace + '\\DWR_ConstructedAbandonedReplaced'
tempList = arcpy.ListFeatureClasses() # This contains too many files, some of which I'm not interested in
extractList = []
for fc in tempList:
 if fc.endswith ('EVTP'): 
 extractList.append(fc) 
print (extractList) #contains only the fc's I'm interested in
for fc in extractList:
 fieldList = arcpy.ListFields(fc)
 joinField = fieldList[4] #this is == 'Permit', and is the join field for the input table and the fc
 fieldValue = fieldList[63] #field I want to join from each fc to inDWR
 arcpy.JoinField_management (inDWR, joinField, fc, joinField, fieldValue)

I keep getting this error:

Runtime error 
Traceback (most recent call last):
 File "<string>", line 6, in <module> #This would be the arcpy.JoinField_management line
 File "c:\program files (x86)\arcgis\desktop10.6\arcpy\arcpy\management.py", line 6593, in JoinField
 raise e
RuntimeError: Object: Error in executing tool

Answer 1

I suspect your problem is:

fieldList = arcpy.ListFields(fc)
joinField = fieldList[4] 
fieldValue = fieldList[63]

joinField and fieldValue will be field objects (look a code sample below help text) not field names which join field wants. Extract name by:

joinField = fieldList[4].name
fieldValue = fieldList[63].name

In my experice Join Field can be very slow. I would create a dictionary using da.SearchCursor and then update your fc with da.UpdateCursor.

Untested:

import arcpy, os
arcpy.env.workspace = r'C:\LaPlata\LaPlataFmTops.gdb'
inDWR = os.path.join(env.workspace, 'DWR_ConstructedAbandonedReplaced')
extractlist = [f for f in arcpy.ListFeatureClasses() if f.endswith('EVTP')]
for fc in extractList:
 fieldList = arcpy.ListFields(fc)
 joinField = fieldList[4] #Now i want Field object to later extract name, type etc. from
 fieldValue = fieldList[63]
 d = {joinField:fieldValue for joinField,fieldValue in arcpy.da.SearchCursor(fc,[joinField.name,fieldValue.name])}
 arcpy.AddField_management(in_table=inDWR, field_name=fieldValue.name, field_type=fieldValue.type) #You might also need a field_length=fieldValue.length if you have a text field.
 with arcpy.da.UpdateCursor(inDWR, [joinField.name,fieldValue.name]) in cursor:
 for row in cursor:
 if row[0] in d:
 row[1] = d[row[0]] #Fetch value from dictionary
 cursor.updateRow(row)
 else:
 #row[1] = 'MISSING'
 pass #Or just skip it