Using input parameters to select layer by attribute

Question

I am trying to create a Python-Toolbox with following Tool:

• inputFeature: A User has to load a Feature
• inputField: Then he has to to select a field from the Input Feature
• inputValue: At the end he has to put in a value (no matter which datatype: date, string, numeric...)

The execute method now should select all rows which are equal to the inputValue.

I already had a working code, but just for numeric inputValues. Another User recomended this code form a past post:

import arcpy
def buildWhereClause(table, field, value):
 """Constructs a SQL WHERE clause to select rows having the specified value
 within a given field and table."""
 # Add DBMS-specific field delimiters
 fieldDelimited = arcpy.AddFieldDelimiters(table, field)
 # Determine field type
 fieldType = arcpy.ListFields(table, field)[0].type
 # Add single-quotes for string field values
 if str(fieldType) == 'String':
 value = "'%s'" % value
 # Format WHERE clause
 whereClause = "%s = %s" % (fieldDelimited, value)
 return whereClause
if __name__ == "__main__":
 inputfc = r"C:\input.shp"
 outputfc = r"C:\output.shp"
 fieldname = "StudyID"
 fieldvalue = 101
 whereclause = buildWhereClause(inputfc, fieldname, fieldvalue)
 arcpy.Select_analysis(inputfc, outputfc, whereclause)

This is the link to the post: Including variable in where clause of arcpy.Select_analysis() It sounds that this would be the perfect solution. But I have no idea how to implement the method in my Python-Toolbox and how to run it with Input-Parameters. Does somebody know how to put the code into the standard Python-Toolbox Codeblock? I mean shouldn't it be used in def execute?

Answer 1

That's how I implemented the Method and how I used it in my Python Toolbox:

def buildWhereClause(self, table, field, value):
 """Methode baut eine SQL whereClause, um die Zeilen zu selektieren, die
 mit einem bestimmten Wert in der Tabelle eines Features mit einem bestimmten
 Wert übereinstimmen."""
 # Fügt DBMS-spezfische field delimiters hinzu
 fieldDelimited = ap.AddFieldDelimiters(table, field)
 # Wählt den field type aus
 fieldType = ap.ListFields(table, field)[0].type
 # Fügt einzelne quotes f?r die String field values hinzu
 if str(fieldType) == 'String':
 value = "'%s'"% value
 # Format der whereClause
 whereClause = "%s = %s" % (fieldDelimited, value)
 return whereClause
def execute(self, parameters, messages):
 """The source code of the tool."""
 inputFeature = parameters[0].valueAsText
 ap.AddMessage("Input Feature: "+ inputFeature)
 inputFieldname = parameters[1].valueAsText
 ap.AddMessage("Feldname: "+ inputFieldname)
 inputValue = parameters[2].valueAsText
 ap.AddMessage("Suchwert: "+ inputValue)
 outputFeature = parameters[3].valueAsText
 ap.AddMessage("Output Feature: "+ outputFeature)
 whereClause = self.buildWhereClause(inputFeature, inputFieldname, inputValue)
 ap.AddMessage("Where Clause: "+ whereClause)
 ap.SelectLayerByAttribute_management(inputFeature,"NEW_SELECTION", whereClause)
 return