topic Re: FieldMap and FieldMappings arrgh.... in Python Questions

FieldMap and FieldMappings arrgh....

JoeBorgione — Sun, 12 Dec 2021 01:26:45 GMT

I'm trying to get FieldMappings—Help | ArcGIS Desktop to work. The need is to append records from one table to records of a different table with the NO_TEST option as the two don't have the same schemas. I've tried with a table to table append, and also with a feature class to feature class append. In both cases I can get the records from one table to append to the target table, and feature geometry to append to the target feature class. But.... None of the attribute values come over in either case. This has to be one of the most complex processes I've ever seen, and I cannot for the life of me see where the issue is. Below is the python script I'm using to do it; pretty much right out of the help page. If anyone has had this work for them, perhaps your second set of eyes is what I need....

import arcpy

in_file1 = r'C:\Replicas\Replicas.gdb\MasterStreetNameFC'
#arcpy.MakeTableView_management(view1,in_file1)
#output_file = r'C:\Replicas\Replicas.gdb\CoordOverlapErrors'
output_file = r'C:\Replicas\Replicas.gdb\Points'

fm_streetname = arcpy.FieldMap()
fm_type = arcpy.FieldMap()
fm_housedir = arcpy.FieldMap()
fm_begrange = arcpy.FieldMap()
fm_endrange = arcpy.FieldMap()
fm_begcoord = arcpy.FieldMap()
fm_endcoord = arcpy.FieldMap()
fm_streetdir = arcpy.FieldMap()
fm_cityjurs = arcpy.FieldMap()
fm_zipcode = arcpy.FieldMap()
fm_oid = arcpy.FieldMap()

fms = arcpy.FieldMappings()

##s_name = 'StreetName'
##s_type = 'Type'
##s_housedir = 'HouseDir'
##s_begrange = 'BegRange'
##s_endrange = 'EndRange'
##s_begcoord = 'BegCoord'
##s_endcoord = 'EndCoord'
##s_streetdir = 'StreetDir'
##s_cityjurs = 'CityJurs'
##s_zipcode = 'ZipCode'
##s_oid = 'OBJECTID'
##
## These variables are commented out
## as I used the actual field names below
## thinking maybe the variables were the problem...


fm_streetname.addInputField(in_file1,'StreetName')
fm_type.addInputField(in_file1, 'Type')
fm_housedir.addInputField(in_file1, 'HouseDIr')
fm_begrange.addInputField(in_file1, 'BegRange')
fm_endrange.addInputField(in_file1, 'EndRange')
fm_begcoord.addInputField(in_file1, 'BegCoord')
fm_endcoord.addInputField(in_file1, 'EndCoord')
fm_streetdir.addInputField(in_file1, 'StreetDir')
fm_cityjurs.addInputField(in_file1, 'CityJurs')
fm_zipcode.addInputField(in_file1, 'ZipCode')
fm_oid.addInputField(in_file1, 'OBJECTID')

StreetName1 = fm_streetname.outputField
Type1 = fm_type.outputField
HouseDir1 = fm_housedir.outputField
BegRange1 = fm_begrange.outputField
EndRange1 = fm_endrange.outputField
BegCoord1 = fm_begcoord.outputField
EndCoord1 = fm_endcoord.outputField
StreetDir1 = fm_streetdir.outputField
CityJurs1 = fm_cityjurs.outputField
Zip1  = fm_zipcode.outputField
OID1 = fm_oid.outputField
#
StreetName2 = fm_streetname.outputField
Type2 = fm_type.outputField
HouseDir2 = fm_housedir.outputField
BegRange2 = fm_begrange.outputField
EndRange2 =  fm_endrange.outputField
BegCoord2 = fm_begcoord.outputField
EndCoord2 =  fm_endcoord.outputField
StreetDir2 = fm_streetdir.outputField
CityJurs2 = fm_cityjurs.outputField
Zip2 = fm_zipcode.outputField
OID2 = fm_oid.outputField

fms.addFieldMap(fm_streetname)
fms.addFieldMap(fm_type)
fms.addFieldMap(fm_housedir)
fms.addFieldMap(fm_begrange)
fms.addFieldMap(fm_endrange)
fms.addFieldMap(fm_begcoord)
fms.addFieldMap(fm_endcoord)
fms.addFieldMap(fm_streetdir)
fms.addFieldMap(fm_cityjurs)
fms.addFieldMap(fm_zipcode)
fms.addFieldMap(fm_oid)

arcpy.Append_management(in_file1,output_file,'NO_TEST',fms)
‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

Re: FieldMap and FieldMappings arrgh....

JamesMacKay3 — Tue, 27 Feb 2018 18:57:12 GMT

I'm not sure if it's strictly necessary or if it's possible to achieve the equivalent result without it, but when creating the FieldMappings object in the past I've called the addTable method immediately after creation, passing in the input dataset(s).

Re: FieldMap and FieldMappings arrgh....

JoeBorgione — Sun, 12 Dec 2021 01:26:47 GMT

Thanks for your reply, but I don't quite follow what you are suggesting. FWIW, it appears I missed this section provided in the help:

# Set the output field properties for both FieldMap objects 
type_name = fm_type.outputField 
type_name.name = 'Veg_Type' 
fm_type.outputField = type_name 
diam_name = fm_diam.outputField 
diam_name.name = 'Veg_Diam' 
fm_diam.outputField = diam_name‍‍‍‍‍‍‍

I'm hoping that's all it is....

Re: FieldMap and FieldMappings arrgh....

JamesMacKay3 — Sun, 12 Dec 2021 01:26:50 GMT

If that doesn't work, try adding this second line after your line 20:

fms = arcpy.FieldMappings()
fms.addTable(in_file1)‍‍

Re: FieldMap and FieldMappings arrgh....

MicahBabinski — Tue, 27 Feb 2018 19:48:10 GMT

Hey Joe,

If you don't want to hard code your field mappings, here's a way to store the info in a table that then you can then use as a parameter in a custom tool. It will build the field mappings object for you and then append the data as specified in your table.

https://community.esri.com/thread/182353-build-arcpy-field-mapping-object-from-table

Micah

Re: FieldMap and FieldMappings arrgh....

JoeBorgione — Tue, 27 Feb 2018 19:55:12 GMT

Hey mbabinski1988‌ ; that looks promising for my application. Thanks for the tip!

Re: FieldMap and FieldMappings arrgh....

KevinBell1 — Tue, 27 Feb 2018 23:06:09 GMT

I've never been a big fan of the fieldmapping quagmire, probably because I'm much too lazy to read the docs. If I were appending to a table NO_TEST style, I'd read the data from the origin table w/ a search cursor and then simply use an insert cursor on the append table and keep my fields straight.

Re: FieldMap and FieldMappings arrgh....

JamesMacKay3 — Tue, 27 Feb 2018 23:21:24 GMT

I usually stick with cursors as well but I've found using off-the-shelf tools and field mappings typically provide better performance than cursors... So if it's something I'm going to be running regularly and performance matters, I bite the bullet and get into mappings.

Re: FieldMap and FieldMappings arrgh....

JoeBorgione — Tue, 27 Feb 2018 23:41:35 GMT

Kev- couldn't agree with you more: field mapping is indeed a quagmire. In this particular case though a cursor is probably going be sluggish at best.

Re: FieldMap and FieldMappings arrgh....

KevinBell1 — Tue, 27 Feb 2018 23:47:26 GMT

My code usually runs off-hours, so I'll take a performance hit for the sake of more simple code. Has anyone bench marked the difference? I thought da.xCursors were super fast!

Re: FieldMap and FieldMappings arrgh....

JoeBorgione — Wed, 28 Feb 2018 01:32:11 GMT

I've applied the da.search cursor in similar situations and they are too slow, if you have a user waiting for the results. However, this particular application may well be served as an over-nighter.

Re: FieldMap and FieldMappings arrgh....

XanderBakker — Sun, 12 Dec 2021 01:26:53 GMT

I'm not a big fan of Field Mappings. I normally prefer using cursors. Perhaps this could work (although I haven't tested it):

import arcpy

in_file1 = r'C:\Replicas\Replicas.gdb\MasterStreetNameFC'
output_file = r'C:\Replicas\Replicas.gdb\Points'

# keys are input field, values are the matching output fields
dct_fields = {'StreetName': 'Street_Name', 'Type': 'StreetType',
               'HouseDIr':'House_Dir', 'BegRange': 'Start_Range',
               'EndRange': 'End_Range', 'BegCoord': 'Start_Coord',
               'EndCoord': 'End_Coord', 'StreetDir': 'Street_Dir',
               'CityJurs': 'City_Jurs', 'ZipCode': 'ZIPcode'}

flds_in = dct_fields.keys()
flds_in.insert(0, 'SHAPE@') # add the geometru field
flds_out = dct_fields.values()
flds_out.insert(0, 'SHAPE@')

with arcpy.da.InsertCursor(output_file, flds_out) as curs_out:
    with arcpy.da.SearchCursor(in_file1, flds_in) as curs_in:
        for row_in in curs_in:
            row_out = tuple(list(row_in))
            curs_out.insertRow(row_out)
‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

Re: FieldMap and FieldMappings arrgh....

JoeBorgione — Wed, 28 Feb 2018 14:56:58 GMT

Let me give that a shot Xander. Thanks!

xander_bakker‌