I need help on the Update Cursor function

[OLANIYANOLAKUNLE]

Im trying to update a field called "GENERATED" with an attribute called "GENERATED" every time i autogenerate a map, i constructed this script and it is not updating and i didnt see an error(s)

rows = arcpy.UpdateCursor("Parcels",'[OBJECTID] = "1"')
row = rows.next()
while row:
    row.setvalue(GENERATED, GENERATED)
    rows.updateRow(row)
    row = rows.next()

Please any suggestions. Im desperate. Thanks

[ChristopherThompson · Accepted solution]

I suspect the naming is throwing it off, if GENERATED is the field name, it looks like you're trying to set the value equal to itself.  Perhaps this will work:

row.setvalue(GENERATED, 'GENERATED')

That way the function can distinguish between a field and a value.
I've also had success with:

row.GENERATED = 'GENERATED'

[MathewCoyle]

Try this.

rows = arcpy.UpdateCursor("Parcels", "[OBJECTID] = 1")

for row in rows:
    row.setValue("GENERATED", "GENERATED")
    rows.updateRow(row)

You shouldn't have quotes around your objectid query selection. Also not sure if you have assigned GENERATED as a variable, but if you haven't you will need quotes. Also make sure you are using the right field delimiters for your OBJECTID field.

[markdenil]

First off, with an arcpy cursor you don't use .next() in a while loop,
you simply itterate the cursor:

for row in rows:
    ...do stuff

Your query string looks problematic
'[OBJECTID] = "1"'
should be something like
'"OBJECTID" = \'1\''
using double quotes on the field instead of bracket delimiters and
single quotes on the string (or no quotes it it is not a string)
The single quotes around the string have to be escaped with a backslash so
you can wrap the whole query in single quotes.
OR you could wrap it all in tripple quotes and not escape....

...three simultaneous answers. that must get some sort of prize.

[MathewCoyle]

...three simultaneous answers. that must get some sort of prize.

The trifecta crown.

[ChrisSnyder]

I might add that your original sytax of .setvalue should in fact be .setValue (case now matters in v10.0 +!!!). also, I think your SQL in the cursor statement was incorrect. Note you ONLY need to use the .setValue() method if your field name is a variable.

This should work:

rows = arcpy.UpdateCursor("Parcels", "OBJECTID = 1")
for row in rows:
    row.GENERATED = 'GENERATED'
    rows.updateRow(row)
del row, rows

Alternately, this should also work, and demonstates the proper use of the .setValue() method:

generatedFieldName = "GENERATED"
rows = arcpy.UpdateCursor("Parcels", "OBJECTID = 1")
for row in rows:
    row.setValue(generatedFieldName) = 'GENERATED'
    rows.updateRow(row)
del row, rows

[ChrisSnyder]

For SAG's (American slang), here's the v10.1 equivalent using the new "data access" update cursor syntax:

fieldList = ["GENERATED"] #list of the field names you want the cursor to return... order is important
rows = arcpy.da.UpdateCursor("Parcels", fieldList, "OBJECTID = 1")
for row in rows:
    row[0] = 'GENERATED' #fields are now refered to in terms of their index in the fieldList
    rows.updateRow(row)

[OLANIYANOLAKUNLE]

Thanks for all your response, but can i start an edit session automatically with arcpy script? Thanks

[MathewCoyle]

Thanks for all your response, but can i start an edit session automatically with arcpy script? Thanks

No, that would require ArcObjects.

[OLANIYANOLAKUNLE]

This is the new code i constructed:


rows = arcpy.UpdateCursor("Parcels", "FID = 0")
>>> for row in rows:
...     row.setvalue("GENERATED", "GENERATED")
...     rows.updateRow(row)
...    

and this is the error message i received:

Runtime error
Traceback (most recent call last):
  File "<string>", line 2, in <module>
  File "C:\Program Files (x86)\ArcGIS\Desktop10.1\arcpy\arcpy\arcobjects\_base.py", line 28, in __getattr__
    raise AttributeError("%s" % attr)
AttributeError: setvalue