UpdateCursor Script Tool

Well, I can't even get past this line of code:

rows1 = gp.UpdateCursor("PS_lyr")

"PS_lyr" is the joined table. I have since exported the .csv to a .dbf to see if that fixed the problem, but it hasn't. I have imported lmpy and everything seems to be fine. It displays all the fields in the joined table with the proper table precursor.fieldname.

I am starting to think I am going to have to come at this from a different direction.

ChrisSnyder

1) Here's how to figure out if a field value is NULL in a searchcursor:

searchRows = gp.searchcursor(fc):
searchRow = searchRows.next()
while searchRow:
   if searchRow.FIELDNAME == None: #or inverse of "... != None:"
      print "It's NULL!"
   searchRow = searchRows.next()
del searchRow
del searchRows

2) A searchcursor is used to simply reterieve (e.g. read) field/record values (read cursor = read access). An updatecursor is used to change existing field/record values in a table. Note that you can't change values in a lookup table (only the join to table) if you are dealing with a joined table situation (updatecursor = write access). An updatecursor has all the functionality of a readcursor, but with the added ability to alter the field/record values. An insertcursor is used to write (aka insert) new records (and field values) into a table.

So here's some things to try:

1. Instead of using the .csv file directly, convert it to a table (.dbf, PGDB, FGDB, etc.) via ArcGIS. That way it will be garannteed to generate an OBJECTID field. I think this is where things are going wrong for you.

2. Just a note: You line of code:

for i in range(0,numSchools):

should probably be

for i in range(0,numSchools + 1):

because:

for i in range (0,5):
print i
0
1
2
3
4

Alright, I have made a couple of changes and still no success. But, maybe the results will be enlightening. I was originally using a gp.SearchCursor function instead of an UpdateCursor function (I don't really know what the difference is). Since changing to the UpdateCursor function, the script crashes at that line if I pass in a joined table. Is it possible that UpdateCursor doesn't work with a join? It did not crash when I passed in only the feature class.

Thanks.

The the following line of code was how I tried to trap for NULL values.

if M[0][1] > 0:

Realizing this may not work, I changed it to

if M[0][1] <> "NULL":

However, it still doesn't work.

My join seems to be working fine and the value I am trying to transfer is a string. As I mentioned in my previous post, this function does not seem to work even without a join. I tried to just set the value to "xyz", but got the same error.

ChrisSnyder

I assume your .csv file has the necessary OID field, right?

It would be very useful to look at the field values to make sure the join is happening the way you think it is. A while back I wrote a sort of helper python module that among other things, can help diagnose things like this: http://arcscripts.esri.com/details.asp?dbid=15290

Basically all you have to do is copy the lmpy.py file your C:\Python2x\Lib folder.

Then in PythonWin, IDLE, etc.:

import lmpy
lmpy.listRecords("my_feature_layer")

This will list the field names and field values of the 1st 25 records such as: (note my example doesn't have a joined table).

RECORD #1
----------------------------------------------------------------------------------------------------
OBJECTID: 1
Shape: <geoprocessing describe geometry object object at 0x00C1A188>
Shape_Length: 393.699999988
Shape_Area: 9687.48062441
ACRES: 0.222393953728

RECORD #2
----------------------------------------------------------------------------------------------------
OBJECTID: 2
Shape: <geoprocessing describe geometry object object at 0x00C1A9F8>
Shape_Length: 393.699999988
Shape_Area: 9687.48062441
ACRES: 0.222393953728

RECORD #3
----------------------------------------------------------------------------------------------------
OBJECTID: 3
Shape: <geoprocessing describe geometry object object at 0x00C1A188>
Shape_Length: 393.700000018
Shape_Area: 9687.48062588
ACRES: 0.222393953762

Are the field values in your join table what you expected? Are some of the joined field values NULL? If so, you will need to exclude the NULLs (the "can't update field values to NULL" bug is a long standing issue that was finally fixed with v10).

Also, take a look at the lmpy.listfields() function. Could it be you are trying transfer a text field into a integer field or something to that effect?

That doesn't work, I already tried it. I am actually joining a .csv to a shapefile. The String variable does represent a field in the "parent" join table.

In order to make sure there wasn't an issue with trying to calculate a joined field, I took the function and tried to set the value of the row in the original shapefile. It still doesn't work and I am getting an error that says

[INDENT]ERROR 999999: Error executing function[/INDENT]

ChrisSnyder

How about getting rid of the square brackets, since you are referencing a field name and not actual SQL? I'm assuming this is a PGDB data source that has some other table joined to it. Note that the field name that the 'String' variable represents must be in the "parent" join table, and not the look up table.

row.SetValue("ScenarioTemplate_1011." + String, school)

Since you were able to understand and help in this thread, I thought I would post my question here. The section of code that is failing is:

rows = gp.SearchCursor("PS_lyr")
row = rows.next()

try:
    while row:
        for i in range(0,numSchools):
            school = row.GetValue(Elem)
            M[1] = school

        M.sort(lambda x, y: cmp(x[1], y[1]))
        M.reverse()

        if M[0][1] > 0:
            school = M[0][0]
            row.SetValue("[ScenarioTemplate_1011." + String + "]", school)

        gp.AddMessage("You made it through the if statement")
        rows.UpdateRow(row)
        row = rows.next()

except:
    gp.AddError("Failed to set the value of new scenario field to new school assignment")

Specifically, it is failing on the row.SetValue line. Any thoughts?

Thanks.

******
Could there be some kind of lock or permission on the FC in the personal geodatabase that is keeping the field SUBDIV from being updated?

I'm not real familiar with personal geodatabase (mdb's). I created one just to test the code but I don't use them otherwise. Perhaps you could convert your two tables to a File Geodatabase to test your theory.

I know the code works because I've ran it here and it updated the field "SUBDIV". I have to think it's something simple
like a misspelled field name (in the data or the code) or improper indenting or something like that.

******
Could there be some kind of lock or permission on the FC in the personal geodatabase that is keeping the field SUBDIV from being updated?

I know the code works because I've ran it here and it updated the field "SUBDIV". I have to think it's something simple
like a misspelled field name (in the data or the code) or improper indenting or something like that.

I will double-check everything.

I added in a few more print commands to see where the code is failing...it looks like the following code is not working for some reason.....maybe it doesn't like using a variable. Like earlier the code runs without any errors but it still doesn't change the name in the SUBDIV field in the FC....I'm stumped.

row2.SUBDIV = p

I know the code works because I've ran it here and it updated the field "SUBDIV". I have to think it's something simple
like a misspelled field name (in the data or the code) or improper indenting or something like that.

OK,
1.) copy & paste my code
2.) edit these 3 to match your mdb and file names:
gp.Workspace = "C:/junk/temp.mdb"
InputFC = "A"
TAB = "B"
3.) Let me know what happens.

I added in a few more print commands to see where the code is failing...it looks like the following code is not working for some reason.....maybe it doesn't like using a variable. Like earlier the code runs without any errors but it still doesn't change the name in the SUBDIV field in the FC....I'm stumped.

row2.SUBDIV = p

OK,
1.) copy & paste my code
2.) edit these 3 to match your mdb and file names:
gp.Workspace = "C:/junk/temp.mdb"
InputFC = "A"
TAB = "B"
3.) Let me know what happens.

Does your code look something like this (other than I changed the table names and mdb name so I would test here).

This code works:

import arcgisscripting
gp = arcgisscripting.create()

gp.Workspace = "C:/junk/temp.mdb"

inputFC = "A"
TAB = "B"

#Table Loop
cur1 = gp.SearchCursor(TAB)
row1 = cur1.Next()
while row1:
    
    #Get the values from the fields(tab)
    c = row1.GetValue("CATEGORY")
    s = row1.GetValue("SUBNO")
    p = row1.GetValue("PROJECT")    

    print "\nc = "+str(c)
    print "s = "+str(s)
    print "p = "+str(p)

    #fc loop
    cur2 = gp.UpdateCursor(inputFC)
    row2 = cur2.Next()
    while row2:
        #Get the values from the fields(fc)
        t = row2.GetValue("Category")
        l = row2.GetValue("LISTNUM")
        n = row2.GetValue("SUBDIV")

        print "t = "+t
        print "l = "+l
        print "n = "+str(n)

        #Populate field in the fc based on a match
        if t == c and l == s:
            row2.SUBDIV = p            

        #Execute the new value to the fc
        cur2.UpdateRow(row2)
        #fc next
        row2 = cur2.Next()

    #table next
    row1 = cur1.Next()

del cur2
del cur1

print "\nDone. \n"

Here's mine.....

import win32com.client

gp = win32com.client.Dispatch("esriGeoprocessing.GpDispatch.1")

gp.Workspace = "C:\\GISProjects\\ProjectListUpdate.mdb"

FC = "Lines"
TAB = "PROJECTLIST"

#Table Loop
cur1 = gp.SearchCursor(TAB)
row1 = cur1.Next()
while row1:
    #Get the values from the fields(tab)
    c = row1.GetValue("CATEGORY")
    s = row1.GetValue("SUBNO")
    p = row1.GetValue("PROJECT")

    print "Table Category ="+str(c)
    print "Table Subno ="+str(s)
    print "Table Project Name ="+str(p)

    #fc loop
    cur2 = gp.UpdateCursor(FC)
    row2 = cur2.Next()
    while row2:
        #Get the values from the fields(fc)
        t = row2.GetValue("Category")
        l = row2.GetValue("LISTNUM")
        n = row2.GetValue("SUBDIV")

        #Populate field in the fc based on a match
        if t == c and l == s:
            row2.SUBDIV = p

        #Execute the new value to the fc
        cur2.UpdateRow(row2)
        #fc next
        row2 = cur2.Next()

    #table next
    row1 = cur1.Next()

del cur2
del cur1

print "\nDone. \n"

Does your code look something like this (other than I changed the table names and mdb name so I would test here).

This code works:

import arcgisscripting
gp = arcgisscripting.create()

gp.Workspace = "C:/junk/temp.mdb"

inputFC = "A"
TAB = "B"

#Table Loop
cur1 = gp.SearchCursor(TAB)
row1 = cur1.Next()
while row1:
    
    #Get the values from the fields(tab)
    c = row1.GetValue("CATEGORY")
    s = row1.GetValue("SUBNO")
    p = row1.GetValue("PROJECT")    

    print "\nc = "+str(c)
    print "s = "+str(s)
    print "p = "+str(p)

    #fc loop
    cur2 = gp.UpdateCursor(inputFC)
    row2 = cur2.Next()
    while row2:
        #Get the values from the fields(fc)
        t = row2.GetValue("Category")
        l = row2.GetValue("LISTNUM")
        n = row2.GetValue("SUBDIV")

        print "t = "+t
        print "l = "+l
        print "n = "+str(n)

        #Populate field in the fc based on a match
        if t == c and l == s:
            row2.SUBDIV = p            

        #Execute the new value to the fc
        cur2.UpdateRow(row2)
        #fc next
        row2 = cur2.Next()

    #table next
    row1 = cur1.Next()

del cur2
del cur1

print "\nDone. \n"

Is it printing the word "Match" and not writing anything or is it not getting into the if statement at all?

It looks like it is this part of the code that is not working for some reason. It's not updating the FC field called SUBDIV with the information that is in variable p.
When I open the FC it still has the old info in it. Thanks.

#Execute the new value to the fc
cur2.UpdateRow(row2)
#fc next
row2 = cur2.Next()

Any ideas on why the new SUBDIV data does not show in the FC?

Is it printing the word "Match" and not writing anything or is it not getting into the if statement at all?

Tested this morning the code runs without any errors....however it doesn't replace the SUBDIV in the FC with the data from the table.

#Populate field in the fc based on a match
        if t == c and l == s:
            print "Match"
            row2.SUBDIV = p

        #Execute the new value to the fc
        cur2.UpdateRow(row2)
        #fc next
        row2 = cur2.Next()

Any ideas on why the new SUBDIV data does not show in the FC?

I think I see it, the cursor on your FC needs to be a UpdateCursor (not a SearchCursor).

Tested this morning the code runs without any errors....however it doesn't replace the SUBDIV in the FC with the data from the table.

#Populate field in the fc based on a match
        if t == c and l == s:
            print "Match"
            row2.SUBDIV = p

        #Execute the new value to the fc
        cur2.UpdateRow(row2)
        #fc next
        row2 = cur2.Next()

I think I see it, the cursor on your FC needs to be a UpdateCursor (not a SearchCursor).

That seems to be it...thanks . I will run it on some test data tomorrow.

Thanks Again.

I think I see it, the cursor on your FC needs to be a UpdateCursor (not a SearchCursor).

What sort of error are you getting?

>>> Table Category =D
Table Subno =5865
Table Project Name =McDermott Road, East from Coit Road.
Traceback (most recent call last):
File "C:\Python25\Lib\site-packages\pythonwin\pywin\framework\scriptutils.py", line 325, in RunScript
exec codeObject in __main__.__dict__
File "C:\Student\MyFolder\test1.py", line 37, in <module>
cur2.UpdateRow(row2)
File "<COMObject <unknown>>", line 2, in UpdateRow
com_error: (-2147352567, 'Exception occurred.', (0, u'DAO.TableDefs', u'Item not found in this collection.', u'jeterr40.chm', 5003265, -2147467259), None)
>>>

What sort of error are you getting?

rdharles, still not working...any ideas? Thanks.

import win32com.client

gp = win32com.client.Dispatch("esriGeoprocessing.GpDispatch.1")

gp.Workspace = "C:\\GISProjects\\ProjectListUpdate.mdb"

FC = "Lines"
TAB = "PROJECTLIST"

#Table Loop
cur1 = gp.SearchCursor(TAB)
row1 = cur1.Next()
while row1:
    #Get the values from the fields(tab)
    c = row1.GetValue("CATEGORY")
    s = row1.GetValue("SUBNO")
    p = row1.GetValue("PROJECT")

    print "Table Category ="+str(c)
    print "Table Subno ="+str(s)
    print "Table Project Name ="+str(p)

    #fc loop
    cur2 = gp.SearchCursor(FC)
    row2 = cur2.Next()
    while row2:
        #Get the values from the fields(fc)
        t = row2.GetValue("Category")
        l = row2.GetValue("LISTNUM")
        n = row2.GetValue("SUBDIV")

        #Populate field in the fc based on a match
        if t == c and l == s:
            row2.SUBDIV = p

        #Execute the new value to the fc
        cur2.UpdateRow(row2)
        #fc next
        row2 = cur2.Next()

    #table next
    row1 = cur1.Next()

del cur2
del cur1

print "\nDone. \n"

rdharles, thanks for the quick post. I am a novice at this and it's been a few years since I have taken the intro class so it might take me a while to incorporate my information into the code to test. This should give me a really good start.

Thanks Again

Below is my last attempt before I gave up last time.

import win32com.client

gp = win32com.client.Dispatch("esriGeoprocessing.GpDispatch.1")

gp.Workspace = "C:\\GISProjects\\ProjectListUpdate.mdb"

inputFC = "Lines"
TAB = "PROJECTLIST"

cur1 = gp.SearchCursor(TAB)

row1 = cur1.Next()

c = row1.GetValue("CATEGORY")
s = row1.GetValue("SUBNO")
p = row1.GetValue("PROJECT")

print c
print s
print p

cur2 = gp.SearchCursor(inputFC)
row2 = cur2.Next()

t = row2.GetValue("Category")
l = row2.GetValue("LISTNUM")
n = row2.GetValue("SUBDIV")
field = "SUBDIV"

print t
print l
print n

print c
print s
print p

if "Category" == c and "LISTNUM" == s:
    cur = gp.UpdateCursor(inputFC)
    row2 = cur2.Next()
while row2:
    row2.SetValue(field, row2.SUBDIV, row1.PROJECT)
    cur2.UpdateRow(row2)
    row2 = cur2.Next()
else:
    row1 = cur1.Next()




del cur

rickyl15,
Here's an example of reading from a table (dbf file) and writing to fc (shapefile).
The SearchCursor reads the dbf, the UpdateCursor writes to the fc.
This should give you a pretty good start.

## Read the dbf and populate the shp.

import arcgisscripting, sys, os
gp = arcgisscripting.create()

gp.workspace = os.getcwd()

dbf = "Apr.dbf"
shp = "Apr2009.shp"

# dbf loop
rows = gp.SearchCursor(dbf)
row = rows.Next()
while row:
    
    # Get the value from the field(dbf)
    value = row.GetValue("ID_NUM")
    
    print "Processing ID_NUM = "+str(value)
        
    # shp loop    
    rows2 = gp.UpdateCursor(shp)
    row2 = rows2.Next()
    while row2:
        # Get the value from the field (shp)
        value2 = row2.GetValue("ID_NUM")

        # Populate field in shp based on a match        
        if value2 < 1740:            
            row2.city_legal = "Lower"      
        if value2 > 1739:            
            row2.city_legal = "Higher"

        # Execute the new value to the shp
        rows2.UpdateRow(row2)            
        # shp next
        row2 = rows2.Next()         
    
    # dbf next
    row = rows.Next()

del rows2
del rows

print "\nDone.\n"

Corey,

Glad I could help.

I prefer using only "if" statements. That way each statement is evaluated individually instead of the whole thing being tied together in an if/elif/else.

Not sure if they are bringing back the credit/completed/points system. I thought I read somewhere that they were but it appears it is not working now.