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Search Cursor Structure

JamesSmith7

I am using a SearchCursor to return a value from a selected attribute field. But, the cursor does not work or create an error. The ValueGain filed is a Long field type that is has not been set to a string. I am only using the SearchCursor to return a value in the tool dialog window.

arcpy.SelectLayerByAttribute_management(lyr, "NEW_SELECTION", whereClause) df.extent = lyr.getSelectedExtent() df.scale = df.scale*1.1 arcpy.AddMessage(str(whereClause))  cursor = arcpy.da.SearchCursor("Land", ["ValueGain"]) for row in cursor:  arcpy.AddMessage(str(ValueGain))  del row  del cursor

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Accepted answers

ArkadiuszMatoszka

Hi,

When using arcpy.da.SearchCursor() each row is returned as list of values, correct call to get attribute value for row would be:

arcpy.SelectLayerByAttribute_management(lyr, "NEW_SELECTION", whereClause)  df.extent = lyr.getSelectedExtent()  df.scale = df.scale*1.1  arcpy.AddMessage(str(whereClause))   cursor = arcpy.da.SearchCursor("Land", ["ValueGain"])  for row in cursor:   arcpy.AddMessage(str(row[0])) # row[0] = first element of list that represents row  del row  del cursor

In case from your code:

arcpy.AddMessage(str(ValueGain))

ValueGain is unassigned variable, so you will get error.
Regards
Arek

All comments

ChrisSnyder

each row is returned as list of values

To be more precise, each row is returned as a Python tuple... which is similar to a Python list, but one that can't be rearanged/sorted (aka an imutable list).

In Python:

tupleExample = (1,2,3,4)
listExample = [1,2,3,4]

JamesSmith7

Thanks for the quick response. Your suggestion worked.

ArkadiuszMatoszka

Hi,

When using arcpy.da.SearchCursor() each row is returned as list of values, correct call to get attribute value for row would be:

arcpy.SelectLayerByAttribute_management(lyr, "NEW_SELECTION", whereClause)  df.extent = lyr.getSelectedExtent()  df.scale = df.scale*1.1  arcpy.AddMessage(str(whereClause))   cursor = arcpy.da.SearchCursor("Land", ["ValueGain"])  for row in cursor:   arcpy.AddMessage(str(row[0])) # row[0] = first element of list that represents row  del row  del cursor

In case from your code:

arcpy.AddMessage(str(ValueGain))

ValueGain is unassigned variable, so you will get error.
Regards
Arek

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