topic Python Script Running in Model Builder before another Operation Starts in ModelBuilder Questions

Python Script Running in Model Builder before another Operation Starts

ClintonCooper1 — Mon, 14 Sep 2015 19:09:22 GMT

I have a built a rather large Model in Model Builder that process several
million records. Part of the model includes running an update cursor
script before it does a Dissolve on that dataset. I have gotten the
python script run, but not in the right order. In fact, it only runs at
the very end of the whole model. As I am new to Model Builder, I cannot
figure out how to get it to run in the proper order, before the Dissolve
process and not at the very end of the whole model. Thanks for your
help in advance!!

I am running ArcGIS 10.3

Re: Python Script Running in Model Builder before another Operation Starts

WesMiller — Mon, 14 Sep 2015 19:19:58 GMT

Try setting your preconditions. A quick tour of using preconditions—Help | ArcGIS for Desktop

Re: Python Script Running in Model Builder before another Operation Starts

ClintonCooper1 — Mon, 14 Sep 2015 19:25:15 GMT

Thanks/ When I try t set the precondition, I get a pop up that says: Can only Connect a Variable to a Process.

The script is just a .py file that I have imported into my toolbox. Do I need to set up anything within that text file to get it to be set as a precondition?

Re: Python Script Running in Model Builder before another Operation Starts

WesMiller — Mon, 14 Sep 2015 19:31:54 GMT

Does your script have any input output variables you could then set the precondition of the process following the script to wait for the script.

Re: Python Script Running in Model Builder before another Operation Starts

ClintonCooper1 — Mon, 14 Sep 2015 19:35:29 GMT

It does not. It just simply runs an update cursor calculation on a dataset updating a bunch of fields.

here is my script:

import arcpy, collections
fc = r"E:\MATCH_WARD"

fields = ('AMOUNT','PARTY_IDEOLOGY','UNK','REP','DEM','CONT_DEM_NUM','CONT_REP_NUM','CONT_UNK_NUM')

with arcpy.da.UpdateCursor(fc, fields) as cursor:
   for row in cursor:
     if row[1] == "UNK":
         row[2]=row[0]
         row[7]=1
     else:
         row[2]=0
         row[7]=0

     if row[1] == "REP":
         row[3]=row[0]
         row[6]=1
     else:
         row[3]=0
         row[6]=0

     if row[1] == "DEM":
         row[4]=row[0]
         row[5]=1
     else:
         row[4]=0
         row[5]=0

cursor.updateRow(row)
del row
del cursor

Re: Python Script Running in Model Builder before another Operation Starts

WesMiller — Mon, 14 Sep 2015 19:41:27 GMT

You may have to export your model to python and put your update cursor script in, where you need it to go or change your script to have a dummy output that you could use for preconditions.

Re: Python Script Running in Model Builder before another Operation Starts

ClintonCooper1 — Mon, 14 Sep 2015 19:50:25 GMT

Can you give an example of what a dummy ouput would look like and how to connect the script to the dummy ouput and then to the next process in Model builder? Thanks again!!

Re: Python Script Running in Model Builder before another Operation Starts

WesMiller — Sun, 12 Dec 2021 10:01:45 GMT

Add this code to your script in your tool set a variable as derived and as text

import arcpy
dvariable = "Dummy"
arcpy.SetParameterAsText(0,dvariable)

Re: Python Script Running in Model Builder before another Operation Starts

ClintonCooper1 — Mon, 14 Sep 2015 20:08:14 GMT

Thank you so much for your help and patience with me! I fully understand about adding the text within my script and all that, my trouble is understanding what I need to do in model builder. Can you give a bit more detailed instruction for what I need to do within model builder such as setting a variable as derived and as text? thanks !!!!!!!!

Re: Python Script Running in Model Builder before another Operation Starts

WesMiller — Mon, 14 Sep 2015 20:29:37 GMT

Once you've added the code to your script you'll need to fix your tool to show your changes. Right click your tool in catalog and select properties then set your tool like below you may need to remove and reload into your model

Re: Python Script Running in Model Builder before another Operation Starts

ClintonCooper1 — Tue, 15 Sep 2015 00:20:48 GMT

THAT WORKED PERFECTLY, THANK YOU SO MUCH!!!!