[GIS] Displaying raised error messages to user in ArcGIS Geoprocessing Results window

arcgis-10.0arcpygeoprocessing

Can print statements raised from a custom exception be displayed in the Geoprocessing Results window?

I modified a script that I found that takes two inputs from a user, finds the associated feature, then zooms to the feature. The tool works fine. I am trying to make it more user-friendly by automatically formatting the inputs to have the correct amount of characters. I added a messagebox that tells the user if they have too many characters in the input box, but I used easygui to create that (a Python library for GUIs). Instead, I would like to use the gp results window to display the message. I thought that I formatted the raise and except statements correctly but the tool runs and I get a completed result and not my error message. I tried the arcpy help from esri and did not get the results I was looking for.

class BadInputError(Exception):
    pass

# Import arcpy module
import arcpy, sys, string
from arcpy import env

try:
    def checkInput(inp):
        mNCount = len(inp)
        trigger = 0
        while trigger == 0:
            if  mNCount == 4:
                trigger = 1
            elif mNCount > 4:
                inp = ''
                trigger = -1
                raise BadInputError
            elif mNCount == 3:
                inp = '0' + inp
                trigger = 1
            elif mNCount == 2:
                inp = '00' + inp
                trigger = 1
            elif mNCount == 1:
                inp = '000' + inp
                trigger = 1
        return inp


    # Script arguments
    MapNumber = arcpy.GetParameterAsText(0)
    MapNumber = checkInput(MapNumber)
    ParcelNumber = arcpy.GetParameterAsText(1)
    ParcelNumber = checkInput(ParcelNumber)

    Expression = (""" "MAP" = '%s' AND "PARCEL" = '%s'""") %(MapNumber,ParcelNumber)

    # Local variables:
    GISData_GISDATA_CAD_PARCEL2009_WHOLE = "Database Connections\\GISUser.sde\\GISData.GISDATA.CAD_PARCEL2009_WHOLE"
    Output_Layer_Name = Expression
    Output_Layer = "ParcelSelection"

    # Process: Select Layer By Attribute
    arcpy.SelectLayerByAttribute_management("2009 Parcel Points", "NEW_SELECTION", Expression)

    # Zoom to Selected Features
    mxd = arcpy.mapping.MapDocument('CURRENT') 
    df = arcpy.mapping.ListDataFrames(mxd, "Layers") [0] 
    df.zoomToSelectedFeatures()
    df.scale = 8000
    arcpy.RefreshActiveView()

except BadInputError:
    print "Too many characters.  Run again"

except Exception, e:
    # If an error occurred, print line number and error message  
    import traceback, sys
    tb = sys.exc_info()[2]
    print "Line %i" % tb.tb_lineno
    print e.message

Best Answer

I think you're looking for arcpy.AddMessage.

The four ArcPy functions for writing messages are as follows:

  • AddMessage("message")—For general informative messages (severity = 0).
  • AddWarning("message")—For warning (severity = 1).
  • AddError("message")—For errors (severity = 2).
  • AddIDMessage(MessageType, MessageID, AddArgument1, AddArgument2)—Used for both errors and warnings (the MessageType argument determines severity).
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