ArcPy Cursor iteration update

Question

I'm trying to get the cursor to iterate through rows and fields looking for blank or null values and change them to 999999 but it's not changing anything.

fc = "C:\Users\\bbrock\Documents\ArcGIS\Ports.shp"

# Create a search cursor 
#
rows = arcpy.SearchCursor(fc) 

# Create a list of string fields
fields = arcpy.ListFields(fc, "", "String")

for row in rows:
    for field in fields:
        if field.type != "Geometry":
            if row.getValue(field.name) == '':
                row.setValue(field.name, '999999')              
                print "%s: Value = %s" % (field.name, row.getValue(field.name))

            if row.isNull(field.name):
                row.setValue(field.name, '999999')              
                print "%s: Value = %s" % (field.name, row.getValue(field.name))             

Answer 1

A SearchCursor is read-only. You want to use an UpdateCursor. Also don't forget to call the cursor's updateRow method after setting a row's values.

See Accessing data using cursors in the help for more information.

Answer 2

You are using arcpy.SearchCursor which is not able to update values. You need to use an arcpy.UpdateCursor. There are a number of other issues with this code but I will just stick to answering your specific question.

Answer 3

Here is a final working copy of my code using with arcpy.da.updateCursor as... as recommended.

fc = "C:/Users/bbrock/Documents/ArcGIS/Default.gdb/Ports_Admin_Join"

fields = arcpy.ListFields(fc, "", "String")

for field in fields:
    with arcpy.da.UpdateCursor(fc, field.name) as rows:
        for row in rows:
            if field.type != "geometry" and field.length > 5:
                if row[0] == None or row[0] == ' ':
                    row[0] = '999999'
                    rows.updateRow(row)    
                    print "%s: Value = %s" % (field.name, row[0])