I'm trying to use the ToolValidator function to update the content of the drop down lists. I've followed the steps from https://blogs.esri.com/esri/arcgis/2011/08/25/generating-a-choice-list-from-a-field/ but need to take it a step further and populate the 'HA' drop down list with the values in the 'HarvestArea' field that start with the 'ForestID'.
Any help on how to format this in the ToolValidator script (see below) would be much appreciated!
import arcpy
class ToolValidator(object):
"""Class for validating a tool's parameter values and controlling
the behavior of the tool's dialog."""
def __init__(self):
"""Setup arcpy and the list of tool parameters."""
self.params = arcpy.GetParameterInfo()
self.fcfield = (None, None)
def initializeParameters(self):
"""Refine the properties of a tool's parameters. This method is
called when the tool is opened."""
return
def updateParameters(self):
"""Modify the values and properties of parameters before internal
validation is performed. This method is called whenever a parmater
has been changed."""
if self.params[0].value and self.params[1].value:
fc, col = str(self.params[0].value), str(self.params[1].value)
if self.fcfield != (fc, col):
self.fcfield = (fc, col)
self.params[2].filter.list = [str(val) for val in
sorted(
set(
row.getValue(col)
for row in arcpy.SearchCursor(fc,
fields=col)
)
)
]
if self.params[2].value not in self.params[2].filter.list:
self.params[2].value = self.params[2].filter.list[0]
def updateMessages(self):
"""Modify the messages created by internal validation for each tool
parameter. This method is called after internal validation."""
return
Accepted Solutions
I looked at the blog post mentioned in your post. I believe you need to add an additional parameter for the name of the second field. The following code gives you an idea of what to add/modify in the validator section. Once you have the value of the first field, it will be used in a where clause to filter the results of the second field selection. Note that the code does not check for field types, so the where clause may not be properly formed.
import arcpy
class ToolValidator(object):
"""Class for validating a tool's parameter values and controlling
the behavior of the tool's dialog."""
def __init__(self):
"""Setup arcpy and the list of tool parameters."""
self.params = arcpy.GetParameterInfo()
self.fcfld_1 = (None, None)
self.fcfld_2 = (None, None)
def initializeParameters(self):
"""Refine the properties of a tool's parameters. This method is
called when the tool is opened."""
return
def updateParameters(self):
"""Modify the values and properties of parameters before internal
validation is performed. This method is called whenever a parameter
has been changed."""
if self.params[0].value and self.params[1].value and self.params[2].value and self.params[3].value: # get second field and value list
fc, c_2 = str(self.params[0].value), str(self.params[3].value)
if self.fcfld_2 != (fc, c_2):
self.fcfld_2 = (fc, c_2)
wc = "{} = {}".format(self.params[1].value, str(self.params[2].value)) # where clause does not check field type
self.params[4].filter.list = [str(val) for val in sorted(set(row.getValue(c_2) for row in arcpy.SearchCursor(fc,fields=c_2, where_clause=wc)))]
if self.params[4].value not in self.params[4].filter.list:
self.params[4].value = self.params[4].filter.list[0]
elif self.params[0].value and self.params[1].value: # get first field and value list
fc, c_1 = str(self.params[0].value), str(self.params[1].value)
if self.fcfld_1 != (fc, c_1):
self.fcfld_1 = (fc, c_1)
self.params[2].filter.list = [str(val) for val in sorted(set(row.getValue(c_1) for row in arcpy.SearchCursor(fc,fields=c_1)))]
if self.params[2].value not in self.params[2].filter.list:
self.params[2].value = self.params[2].filter.list[0]
return
def updateMessages(self):
"""Modify the messages created by internal validation for each tool
parameter. This method is called after internal validation."""
returnHope this helps.
I looked at the blog post mentioned in your post. I believe you need to add an additional parameter for the name of the second field. The following code gives you an idea of what to add/modify in the validator section. Once you have the value of the first field, it will be used in a where clause to filter the results of the second field selection. Note that the code does not check for field types, so the where clause may not be properly formed.
import arcpy
class ToolValidator(object):
"""Class for validating a tool's parameter values and controlling
the behavior of the tool's dialog."""
def __init__(self):
"""Setup arcpy and the list of tool parameters."""
self.params = arcpy.GetParameterInfo()
self.fcfld_1 = (None, None)
self.fcfld_2 = (None, None)
def initializeParameters(self):
"""Refine the properties of a tool's parameters. This method is
called when the tool is opened."""
return
def updateParameters(self):
"""Modify the values and properties of parameters before internal
validation is performed. This method is called whenever a parameter
has been changed."""
if self.params[0].value and self.params[1].value and self.params[2].value and self.params[3].value: # get second field and value list
fc, c_2 = str(self.params[0].value), str(self.params[3].value)
if self.fcfld_2 != (fc, c_2):
self.fcfld_2 = (fc, c_2)
wc = "{} = {}".format(self.params[1].value, str(self.params[2].value)) # where clause does not check field type
self.params[4].filter.list = [str(val) for val in sorted(set(row.getValue(c_2) for row in arcpy.SearchCursor(fc,fields=c_2, where_clause=wc)))]
if self.params[4].value not in self.params[4].filter.list:
self.params[4].value = self.params[4].filter.list[0]
elif self.params[0].value and self.params[1].value: # get first field and value list
fc, c_1 = str(self.params[0].value), str(self.params[1].value)
if self.fcfld_1 != (fc, c_1):
self.fcfld_1 = (fc, c_1)
self.params[2].filter.list = [str(val) for val in sorted(set(row.getValue(c_1) for row in arcpy.SearchCursor(fc,fields=c_1)))]
if self.params[2].value not in self.params[2].filter.list:
self.params[2].value = self.params[2].filter.list[0]
return
def updateMessages(self):
"""Modify the messages created by internal validation for each tool
parameter. This method is called after internal validation."""
returnHope this helps.
Hi again (Randy Burton), I'm trying to cascade these filter lists another step but I think I'm getting caught up on the where clause (python beginner here!)? I want to use the result from the second filter list (Harvest Area) to then determine the results of the third filter list (Setting).
import arcpy
class ToolValidator(object):
"""Class for validating a tool's parameter values and controlling the behavior of the tool's dialog."""
def __init__(self):
"""Setup arcpy and the list of tool parameters."""
self.params = arcpy.GetParameterInfo()
self.fcfld_1 = (None, None)
self.fcfld_2 = (None, None)
self.fcfld_3 = (None, None)
return
def initializeParameters(self):
"""Refine the properties of a tool's parameters. This method is
called when the tool is opened."""
return
def updateParameters(self):
"""Modify the values and properties of parameters before internal
validation is performed. This method is called whenever a parameter
has been changed."""
forestfld = "Forest"
hafld = "HarvestArea"
settingfld = "Setting"
if self.params[0].value and forestfld and self.params[1].value and hafld and self.params[2].value and settingfld: # get settings
fc2, c_3 = str(self.params[0].value), str(settingfld)
if self.fcfld_3 !=(fc2, c_3):
self.fcfld_3 = (fc2, c_3)
wc1 = "{} = {}".format(str(hafld), str(self.params[2].value))
self.params[3].filter.list = [str(val) for val in sorted(set(row.getValue(c_3) for row in arcpy.SearchCursor(fc2,fields=c_3, where_clause=wc1)))]
if self.params[3].value not in self.params[3].filter.list:
self.params[3].value = self.params[3].filter.list[0]
if self.params[0].value and forestfld and self.params[1].value and hafld: # get harvest area
fc1, c_2 = str(self.params[0].value), str(hafld)
if self.fcfld_2 !=(fc1, c_2):
self.fcfld_2 = (fc1, c_2)
wc = "{} = {}".format(str(forestfld), str(self.params[1].value))
self.params[2].filter.list = [str(val) for val in sorted(set(row.getValue(c_2) for row in arcpy.SearchCursor(fc1,fields=c_2, where_clause=wc)))]
if self.params[2].value not in self.params[2].filter.list:
self.params[2].value = self.params[2].filter.list[0]
if self.params[0].value and forestfld: # get forest
fc, c_1 = str(self.params[0].value), str(forestfld)
if self.fcfld_1 !=(fc, c_1):
self.fcfld_1 = (fc, c_1)
self.params[1].filter.list = [str(val) for val in sorted(set(row.getValue(c_1) for row in arcpy.SearchCursor(fc,fields=c_1)))]
if self.params[1].value not in self.params[1].filter.list:
self.params[1].value = self.params[1].filter.list[0]
return
def updateMessages(self):
"""Modify the messages created by internal validation for each tool
parameter. This method is called after internal validation."""
return
I'm also getting this error (see attached) where the format of the Harvest Area is 485-384-09.
Any help would be much appreciated!
All of the fields (Forest, HarvestArea and Setting) are text fields. The input feature class will be the same every time, so yes same field names and field types.
Aim is for the end user to select the forest (i.e. 403), they will then get the list of harvest areas within the 403 forest, then once a harvest area is selected (i.e. 403-048-03) then they can select a setting from the next list (i.e. 1, 2 or 3).
Hope that answers your questions.
