topic Re: Python: Using sys.argv[1] in Update Cursor in Geoprocessing Questions

Python: Using sys.argv[1] in Update Cursor

JamesHood — Sun, 12 Dec 2021 16:01:48 GMT

Hello,

I would like to create tool for multiple users with multiple datasets from multiple sources. Each dataset contains the same data, it's just stored differently, mostly just different field names and input locations etc...

Is it possible to insert a variable into an Update Cursor to give the tool more flexibility with multiple users?

For example:

InAge = sys.argv[1]

rows = gp.UpdateCursor("c:\temp\test.dbf")
row = rows.Next()
while row:
    if row.InAge == 25:
        row.Range = "Mid"

Will InAge work as a variable? Or will the cursor look for a field called "InAge" ?

Is this even possible ?

Thanks!

Re: Python: Using sys.argv[1] in Update Cursor

JasonScheirer — Sat, 11 Dec 2021 06:38:59 GMT

Use the getattr builtin:

InAge = gp.GetParameterAsText(0)

rows = gp.UpdateCursor("c:\temp\test.dbf")
row = rows.Next()
while row:
    if getattr(row, InAge) == 25:
        row.Range = "Mid"

Re: Python: Using sys.argv[1] in Update Cursor

JamesHood — Sat, 11 Dec 2021 06:39:01 GMT

I ran a test on that and it works like a charm!

I tried to take it a step further though and I found that I can't use the getattr ( , ) function to allow the user to define what the input field name will be.

InAge = gp.GetParameterAsText(0)
OutField = gp.GetParameterAsText(1)

rows = gp.UpdateCursor("c:\temp\test.dbf")
row = rows.Next()
while row:
    if getattr(row, InAge) == 25:
        getattr(row, OutField) = "Mid" #<-- DOES NOT WORK: RETURNS SYNTAX ERROR AT THIS LINE
        #row.Range = "Mid"

"ERROR: Failed to check - syntax error - can't assign to function call (test.py, line 23)"

I guess the reason it fails is this: In the if line " if getattr(row, InAge) == 25:" we are assigning a user value to the variable then asking IF it equals 25, do the following:

Then in the following, we assigning another user value to the variable to be the FieldName, but then immediately trying to re-assign a new value, changing the FieldName, to the input value for that field. Then python gets confused and screwy.

Unless there is some kind of list or tuple or something that would allow the storage of more than one value in the attribute to be used in this circumstance, I don't know if it would ever work...

Thanks jscheirer,

- James

Re: Python: Using sys.argv[1] in Update Cursor

JasonScheirer — Tue, 10 Aug 2010 16:13:54 GMT

Use setattr:

setattr(row, OutField, "Mid")

Re: Python: Using sys.argv[1] in Update Cursor

ChrisSnyder — Tue, 10 Aug 2010 16:56:03 GMT

Jason:

So is getattr() and setattr() preferable to the esri cursor methods of getvalue() and setvalue(). That is to say, are they faster or for some other reason better? Regardless, seems pretty cool!

Re: Python: Using sys.argv[1] in Update Cursor

JasonScheirer — Wed, 11 Aug 2010 00:49:26 GMT

Functionally they are the same, just getattr and setattr will work on any Python object, not just row objects.