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update an attribute if record found in a query

MatthewWalker1

I am trying to update an attribute in one table, if that record is found in a MakeQuery table (I made a table view of all records not yet processed, and once processed, I want to turn the 'Processed' flag to 'Y').

rows = arcpy.UpdateCursor("Assets") for row in rows:  if row.Processed == "N" and row.Asset_ID == "Asset_Unprocessed.Asset_ID":   row.Processed = "Y"   rows.updateRow(row) del row del rows

I am trying to update in the Assets table the 'Processed' flag to 'Y', IF the Assets key is found in the 'Assets_Unprocessed' table. This does not throw an error, it just does not find and update my test data properly. The issue is the comparison to the Assets_Unprocessed table (the rest of the code works), and I've tried several different ways to type that table (full path, brackets, etc.) and can't seem to get that part to work.

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Accepted answers

jskinner

Hi Matthew,

Try the following:

table = 'assets_unprocessed' assetIDList = []  rows = arcpy.SearchCursor(table) for row in rows:     assetIDList.append(row.Asset_ID)  del row, rows  table2 = 'assets'  for ID in assetIDList:     rows = arcpy.UpdateCursor(table2)     for row in rows:         if row.Asset_ID == ID:             row.Processed = 'Y'             rows.updateRow(row)  del row, rows print 'finished'

All comments

MatthewWalker1

Booya! It finally worked! I noticed that in Jake's last reply that in the SearchCursor function in the append command it reads "...(row.Asset_ID)" rather than "...auRows.Asset_ID)" and that allowed me to get through that bit of code. The rest of Jake's code for running the UpdateCursor worked and the attribute 'Processed' flag did get changed to 'Y'! thanks a million guys!

The one thing I am noticing though, is that I cannot run my entire code all at once (i.e. I can't copy and paste the whole code in the ArcMap Python screen) or I will get an error stating, "Runtime error <type 'exception.NameError'>: name 'row' is not defined". If I run all the code down to the 'del row, rows' section, then after everything runs run that code, no errors, and then I can paste in the UpdateCursor section with no errors, just not all at the same time. I will eventually want to run this from an executable or in batch and not within ArcMap, and am wondering if I will get the same error or not. Any ideas why this error occurs with the whole code, but not if fed in sections?

Again, I really appreciate all the help on this! Now I just have to work on how to make these records spatial, at their measure values, a whole other can of worms!

FYI: final code that seems to work for me, at least piecemeal:

import arcpy
from arcpy import env
import datetime
import os
env.workspace = "c:\Users\matt\Desktop\Projects\Assets\Assets.mdb"

#Make a TableView of Non-Spatial Asset records that need to be processed
arcpy.MakeQueryTable_management (["Assets"], "Asset_Line", "ADD_VIRTUAL_KEY_FIELD", "",[["Asset_ID"], ["Ditch_ID"], ["Begin_Station"], ["End_Station"]], "[Assets.Processed] <> 'Y'")

#Add queried data to Assets_Unprocessed table-to be used by ArcObjects utility to create spatial features
arcpy.Append_management ("Asset_Line", "Assets_Unprocessed")

#Copy attribute data to spatial Asset features

#Call ArcObjects utility to snap 'out of ditch' linear features to spatial Asset features

#Call ArcObjects utility to snap related assets to spatial Asset features

au = "Assets_Unprocessed"
lstIds = []
fld = "Asset_ID"

auRows = arcpy.SearchCursor(au)
for row in auRows:
 lstIds.append(row.Asset_ID)
del row, auRows


table2 = "Assets"
for ID in lstIds:
 rows = arcpy.UpdateCursor(table2)
 for row in rows:
  if row.Asset_ID == ID:
   row.Processed = 'Y'
   rows.updateRow(row)

Zeke

Not sure what to tell you. Worked for me. Are you importing arcpy?

Jake, your method works, but is looping through the table n times in the inner loop the best way to go?

The latest reply mentioned using a SearchCursor without the with...as statement, but I cannot get that to work either (error returns 'Cursor' object has no attribute 'Asset_ID' when I run the SearchCursor code:

Capture.PNG

jskinner

Hi Matthew,

Try the following:

table = 'assets_unprocessed' assetIDList = []  rows = arcpy.SearchCursor(table) for row in rows:     assetIDList.append(row.Asset_ID)  del row, rows  table2 = 'assets'  for ID in assetIDList:     rows = arcpy.UpdateCursor(table2)     for row in rows:         if row.Asset_ID == ID:             row.Processed = 'Y'             rows.updateRow(row)  del row, rows print 'finished'

MatthewWalker1

and FYI, I am running Arc 10.0 SP5 and running my python code within an ArcMap arcpy session.

MatthewWalker1

I have attached a file geodb containing the Assets table and Assets_Unprocessed that I am trying to query and update. The Asset table is queried in a MakeQueryTable for records that have not been processed, and dumped into the table Assets_Unprocessed, to be used by other utilities. Once these records have been processed, I need to flag them as such by changing the 'N' to 'Y' in the Processed attribute within the Assets table.

The latest reply mentioned using a SearchCursor without the with...as statement, but I cannot get that to work either (error returns 'Cursor' object has no attribute 'Asset_ID' when I run the SearchCursor code:

au = "Assets_Unprocessed"
lstIds = []
fld = "Asset_ID"

auRows = arcpy.SearchCursor(au)
for row in auRows:
 lstIds.append(auRows.Asset_ID)

Assets.gdb.zip

jskinner

Greg,

Thanks for the input, I see how that could resolve my issue. I tried running that SearchCursor section of code you supplied, but an error was returned:

Runtime error <type 'exceptions.AttributeError'>: 'Cursor' object has no attribute '__exit__'

I am unfamiliar with the with...as statement so I'm not sure what is missing or needed here. I understand the process of building a list of Asset_ID's from Assets_Unprocessed then searching for records in Assets with those Asset_ID's, but it seems I'm having difficulty in first building that list with the SearchCursor and the use of the with...as statement.

Can you upload a small sample of each dataset in a zipped File Geodatabase?

Zeke

Do you have any Nulls or empty fields in the Asset_ID field? Maybe add an if statement checking for them before appending to the list. What version of Arc are you running?

You may want to modify the SearchCursor arguments to include just the Asset_ID field as well, and make sure someone else isn't accessing the data and putting a lock on it. Or maybe lstIds.append(row.getValue("Asset_ID")). I use arcpy.da, which is a slightly different syntax.

The with...as syntax just provides for automatic garbage collection, so you don't have to manually delete rows or row. Maybe the version in your setup doesn't support with for a SearchCursor, so you could try going back to your original syntax. for that. In that case, consider wrapping it in a try/except block. This is actually what I'd try first. The with...as expects an __exit__ attribute, so if it's not there you'll get this error.


au = "Assets_Unprocessed"
fld = "Asset_ID" 
lstIds = []  

auRows = arcpy.SearchCursor(au) 
for row in auRows:     
    lstIds.append(auRows.Asset_ID)

del auRows
del row 

try:     
    aRows = arcpy.UpdateCursor("Assets") 
    for row in aRows:         
        if row.Processed == "N" and row.Asset_ID in lstIds:             
            row.Processed = "Y"             
            aRows.update(row)
except Exception as e:
     print e.message
     #do whatever

del aRows
del row

MatthewWalker1

Greg,

Thanks for the input, I see how that could resolve my issue. I tried running that SearchCursor section of code you supplied, but an error was returned:

Runtime error <type 'exceptions.AttributeError'>: 'Cursor' object has no attribute '__exit__'

I am unfamiliar with the with...as statement so I'm not sure what is missing or needed here. I understand the process of building a list of Asset_ID's from Assets_Unprocessed then searching for records in Assets with those Asset_ID's, but it seems I'm having difficulty in first building that list with the SearchCursor and the use of the with...as statement.

Zeke

You don't show where you're looping through Asset_Unprocessed. Unless the actual value of Asset_ID is the string "Asset_Unprocessed.Asset_ID", no matches will be found. This isn't an error in the coding; it's doing exactly what it's told to do.

If what you want is to update Assets if there is a match in the ID fields of the two tables, one solution would be to first run a SearchCursor on Assets_Unprocessed and populate a list with all that table's ids. Then run an UpdateCursor on Assets and check if the id value is in the list. Or, if the tables are joined as Jake asks, instead, change your code to check row.Assets_Unprocessed.Asset_ID, or whatever field name the join gave it. However, this wouldn't catch instances where Assets_Unprocessed.Asset_ID wasn't in the row for the matching id, if there are any. Yet another way would be to run the UpdateCursor in a nested loop in a SearchCursor loop, but I think I read somewhere that ESRI discourages nested cursors.

Something like (untested):
au = "Assets_Unprocessed" lstIds = [] # with... syntax automaticalyy deletes auRows, row with arcpy.SearchCursor(au) as auRows: for row in auRows: lstIds.append(auRows.Asset_ID) with arcpy.UpdateCursor("Assets") as aRows: for row in aRows: if row.Processed == "N" and row.Asset_ID in lstIds: row.Processed = "Y" arows.update(row)

jskinner

Hi Matthew,

Are you joining the 'Asset_Unprocessed' table to the 'Assets' table?

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