Using the Calculate Value Tool and messaging in Model Builder

Hornbydd

All,

I came across this blog about using the Calculate Value tool. The blog is for ArcGIS 10 but I was able to adapt an example to 9.3.

I found this blog really useful as I never knew about this particular tool and being able to write if then else logic but still within model builder is extremely useful as it avoids the need for having to build scripts that are ultimately files that sit outside a toolbox.

So I created a simple python function that tested for the existence of a field and output a boolean which is a precondition for what ever. It all worked great.

Now my question is simple, how do you write a message to the output window when a model is running? If you look at the code below I've tried two methods but it nevers writes anything, is it possible?

The code block contained the following code for the Calculate Value tool:

def test(f):
import arcgisscripting
gp = arcgisscripting.create(9.3)
desc = gp.Describe(f)
fi = desc.FieldInfo
f = fi.FindFieldByName("RIVER")
if f == -1:
return "False"
else:
gp.Addmessage("Hello world")
print "Hello Word"
return "True"

The output in the model dialog is:

Executing (Calculate Value): CalculateValue test("%FC%") "def test(f):\n import arcgisscripting\n gp = arcgisscripting.create(9.3)\n desc = gp.Describe(f)\n fi = desc.FieldInfo\n f = fi.FindFieldByName("RIVER")\n if f == -1:\n return "False"\n else:\n gp.Addmessage("Hello world")\n print "Hello Word"\n return "True"" Boolean true
Start Time: Thu Jun 30 17:06:39 2011
Value = True
Executed (Calculate Value) successfully.
End Time: Thu Jun 30 17:06:39 2011 (Elapsed Time: 0.00 seconds)
Executing (Get Count): GetCount "Base data\NRFA_Gauge_Locations" 1661
Start Time: Thu Jun 30 17:06:39 2011
Row Count = 1661
Executed (Get Count) successfully.
End Time: Thu Jun 30 17:06:39 2011 (Elapsed Time: 0.00 seconds)

As you can see I never see Hello World in the output.

Duncan

curtvprice

The ability to create script tools ("embed them in a toolbox") has been around since 9.0.  If you're on 9.3, you can start with this help topic : An overview of creating script tools

Dale, thanks for the link.

What we're talking about here is embedding a script into a toolbox so a separate .py file is not needed. This is a new (and welcome) functionality in 10.0. From the What's" rel="nofollow" target="_blank">http://help.arcgis.com/en/arcgisdesktop/10.0/help/index.html#/What_s_new_for_geoprocessing_in_ArcGIS_10/00qp0000000q000000/]What's New in ArcGIS 10:

...you can import your .py file into the tool (in fact, you must do this to password protect a script tool). This means you don't have to deliver a separate .py file for your script tool to work, the .py will be saved within the toolbox.