Using decorators to initiate an edit session and running update cursors?

RPGIS

Hi,

I came across the use of decorators while watching YouTube videos on python, and I thought that there might be a way to utilize this to run the update cursor method without having to specify multiple functions or program it right off the bat. It seems to run this segment of code just fine, but I wanted to see if anyone else has done anything like this. Any examples that would be greatly appreciated.

 

 

# Python code to illustrate
# Decorators with parameters in Python
def decorator():
     
    def inner(func):
         
        print ('Starting edit process\n')
        
        # Start edit operation
        print (f'edit = arcpy.da.Editor({Database})')
        print ('edit.startEditing(False, True)')
        print ('edit.startOperation()\n')
         
        func()
        
        # Finish edit operation
        print ('edit.stopOperation()')
        print ('edit.stopEditing(True)\n')
        print ('Finished edit process\n')
        
    # returning inner function   
    return inner
 
@decorator()
def my_func():
    s = ' '*4
    print (f'with udpate as cursor:{s}')
    print (f'{s}for row in cursor:')
    print (f'{s*2}if row[tile] in {Dictionary}:')
    print (f'{s*3}row[tile]=row[tile]')
    print (f'{s*3}row[shape]={Dictionary}[row[tile]]')
    print (f'{s*3}cursor.updateRow(row)\n')

Database = 'AFavorites\GIS.gdb'
Dictionary = 'ATest'

 

 

 

JohannesLindner

AFAIK, arcpy has no native decorators. You would have to define them yourself.

But, the arcpy.da.Editor class supports the with statement, which is somewhat similar to a decorator (it can execute code before and after your function). For the with statement to work, a class need to implement the __enter__ and __exit__ methods. These are called when the script enters and exits the with block.

In your example, you're already using the UpdateCursor in a with block. The UpdateCursor's __enter__ and __exit__ methods open and close the cursor and take care of locking the edited tables.

The Editor's __enter__ and __exit__ methods open and close the edit session.

 

with arcpy.da.Editor("your/database.gdb") as edit:
    with arcpy.da.UpdateCursor("Table", ["Field1", "Field2"]) as cursor:
        for row in cursor:
            #...
            cursor.updateRow(row)