topic Search by attributes tool in Python Questions

Search by attributes tool

2Quiker — Thu, 15 May 2025 22:02:08 GMT

I'm developing a script tool that allows users to select specific features on a map. The tool has three parameters:
Layer – The user selects the target map layer.
Layer Field – The user chooses a field within the selected layer.
Layer Field Attribute – The user selects an attribute value within the chosen field.
Once all parameters are set, the user runs the tool. However, despite receiving no errors, nothing gets selected on the map.

Script

import arcpy class ToolValidator: def __init__(self): self.params = None def initializeParameters(self): return def updateParameters(self): # If the layer is selected, and it is a feature layer if self.params[0].value: layer_name = self.params[0].valueAsText try: fields = [f.name for f in arcpy.ListFields(layer_name)] if "PLAT_NAME" in fields: self.params[1].value = "PLAT_NAME" # Auto-populate the field name # Get unique values from the PLAT_NAME field values = set() with arcpy.da.SearchCursor(layer_name, ["PLAT_NAME"]) as cursor: for row in cursor: if row[0]: values.add(row[0]) self.params[2].filter.list = sorted(values) else: self.params[1].value = None self.params[2].filter.list = [] except Exception as e: self.params[1].value = None self.params[2].filter.list = [] return def updateMessages(self): return def main(): # Parameters layer_name = arcpy.GetParameterAsText(0) # Layer name to select from map field_name = arcpy.GetParameterAsText(1) # Field to search (e.g., PLAT_NAME) acc_val = arcpy.GetParameterAsText(2) # Attribute value (e.g., "BRIDGEWATER ESTATES #3") if not layer_name or not field_name or not acc_val: arcpy.AddError("Layer, field name, or search value is missing.") return # Access current project, map, and layout project = arcpy.mp.ArcGISProject("CURRENT") active_map = project.listMaps()[0] layout = project.listLayouts()[0] # Layout is not used here, but included if needed # Get the target layer by name try: target_layer = active_map.listLayers(layer_name)[0] except IndexError: arcpy.AddError(f"Layer '{layer_name}' not found in the map.") return # Build where clause using input values directly (no escaping) expression = "{0} = '{1}'".format(field_name, acc_val) where_clause = str(expression) arcpy.AddMessage(f"Where clause: {where_clause}") # Perform the selection arcpy.management.SelectLayerByAttribute(target_layer, "NEW_SELECTION", where_clause) # Count and report results count = int(arcpy.management.GetCount(target_layer)[0]) if count == 0: arcpy.AddWarning(f"No features found where {field_name} = '{acc_val}'.") else: arcpy.AddMessage(f"Selected {count} feature(s) where {field_name} = '{acc_val}'.")

Re: Search by attributes tool

AlfredBaldenweck — Fri, 16 May 2025 13:56:32 GMT

Gotta ask, why don't you just direct them to select by attribute? Is it because this tool is going to add the selection to the map?

Anyway, whenever you use select by attribute/location, you should ALWAYS assign it to a variable. This bites everyone at some point, and it's a common question here. So, Line 67 should be like

sel = arcpy.management.SelectLayerByAttribute(target_layer, "NEW_SELECTION", where_clause)

Then you can add it to the map, etc.

It might be something else, but at first glance, that's my guess.

Re: Search by attributes tool

HaydenWelch — Fri, 23 May 2025 13:42:56 GMT

I flattened out your code a bit so it's easier to follow, it seems like your general flow is correct, I did add a call to arcpy.GetParameterInfo() in the ToolValidator initialization though.

import arcpy class ToolValidator: def __init__(self): self.params: list[arcpy.Parameter] = arcpy.GetParameterInfo() def initializeParameters(self): ... def updateParameters(self): # No updates if the layer isn't selected yet if not self.params[0].value: return # Get LayerName and Fields layer_name = self.params[0].valueAsText fields = [f.name for f in arcpy.ListFields(layer_name)] # No options if 'PLAT_NAME' is not in the fields if "PLAT_NAME" not in fields: self.params[1].value = None self.params[2].filter.list = [] return self.params[1].value = "PLAT_NAME" # Auto-populate the field name # Get unique values from the PLAT_NAME field values = { plat_name for plat_name, *_ in arcpy.da.SearchCursor(layer_name, ["PLAT_NAME"]) if plat_name } self.params[2].filter.list = sorted(values) return def updateMessages(self): ... def main(): # Parameters layer_name = arcpy.GetParameterAsText(0) # Layer name to select from map field_name = arcpy.GetParameterAsText(1) # Field to search (e.g., PLAT_NAME) acc_val = arcpy.GetParameterAsText(2) # Attribute value (e.g., "BRIDGEWATER ESTATES #3") if not all(layer_name, field_name, acc_val): arcpy.AddError("Layer, field name, or search value is missing.") return # Access current project, map, and layout project = arcpy.mp.ArcGISProject("CURRENT") active_map = project.listMaps()[0] #layout = project.listLayouts()[0] # Layout is not used here, but included if needed # Get the target layer by name layer_match = active_map.listLayers(layer_name) target_layer = layer_match.pop() if layer_match else None if not target_layer: arcpy.AddError(f"Layer '{layer_name}' not found in the map.") return # Build where clause using input values directly (no escaping) where_clause = f"{field_name} = '{acc_val}'" arcpy.AddMessage(f"Where clause: {where_clause}") # Perform the selection try: arcpy.management.SelectLayerByAttribute(target_layer, "NEW_SELECTION", where_clause) except Exception as e: arcpy.AddError(f"!!---Feature Selection Failed:---!!\n{e}") return # Count and report results count = sum(1 for _ in arcpy.da.SearchCursor(target_layer, ['OID@'])) if not count: arcpy.AddWarning(f"No features found where {field_name} = '{acc_val}'.") return arcpy.AddMessage(f"Selected {count} feature(s) where {field_name} = '{acc_val}'.")

When you run the tool, are you getting any messages? If so which messages?