Automating Define Projection within Python script tool?

Question

How would I automate the Define Projection tool so that I can just enter my layer each time?

I have it as a script in toolbox, but I am unsure how to set it so I can just input my layer as GetParameterAsText

Here is the script. I want to replace the "forest.shp" with a layer of my own choosing each time

 # set local variables
 inDataset = "forest.shp"
 coordinateSystem ="GEOGCS['GCS_WGS_1984',DATUM['D_WGS_1984',SPHEROID['WGS_1984',6378137.0,298.257223563]],PRIMEM['Greenwich',0.0],UNIT['Degree',0.0174532925199433]]"
arcpy.DefineProjection_management(inDataset, coordinateSystem)

• MLowry: You could make the input to your tool a Model Parameter. Upon running the tool, it will ask for you input just like when you run it from the Toolbox. Do you know the you can run it as a "batch" as well by right clicking on the Define Projection tool.

Answer 1

You can do it in python by adding

inDataset = arcpy.GetParameterAsText(0)

here is that example.

Understanding_script_tool_parameters

Then add as a script tool. Adding_a_script_tool

Or just set the model param as MLowry suggested. That is probably quicker and easier.

Answer 2

your .py file must be :

import arcpy 
try:
 coordinateSystem ="GEOGCS['GCS_WGS_1984',DATUM['D_WGS_1984',SPHEROID['WGS_1984',6378137.0,298.257223563]],PRIMEM['Greenwich',0.0],UNIT['Degree',0.0174532925199433]]"
 fc = arcpy.GetParameterAsText(0) #your featureclass file
 dessr = arcpy.Describe(fc)
 srr = dessr.spatialReference
 arcpy.AddMessage("Your previous projection: %s" % (srr))
 arcpy.DefineProjection_management(fc, coordinateSystem)
 arcpy.AddMessage("Your process finished...")
except:
 arcpy.AddMessage("Cant trasformed new projection")

and then follow theJones direction....