Yes, It worked
i need to change frappe.utils.format_date function but none of hooks.py method and monkey_patching method worked for me!!!
in second method when i use function just after load_monkey_patches(), value has been returned from my new function but in other places such as site, value returned from frappe.
any idea?
can you explain with some examples for build_my_thing works?
could you please explain more what the problem you did?
Write these in your custom app
Override class method:
from erpnext.selling.doctype.sales_order.sales_order import SalesOrder
SalesOrder.validate = yourmethod
Override standard method:
from frappe import utils
utils.cstr = yourmethod
Where in the init.py file ?
Can someone please confirm frappe.core doctype classes are also part of this? I am trying to override “UserPermission” class (from frappe.core.doctype) and it is not working. However docTypes in ERPNext I am able to.
There is a hook for that.
Let’s continue this discussion 
Monkey patch is ok. Using hooks.py is ok.
Now let’s get into more details.
There is a non-Class method that I override successfully.
File to be overridden: frappe.desk.reportview.py
Method to be overridden: get_form_params(), the original code is shown below:
def get_form_params():
“”“Stringify GET request parameters.”“”
data = frappe._dict(frappe.local.form_dict)
clean_params(data)
validate_args(data)
return data
The clean_params(data) and validate_args(data) will call other functions within reportview.py.
Now I want to add a custom function just before
return data
The problem is that I need to copy the whole of reportview.py to my new override.py because some function doesn’t do a “return”; “data” will be lost during the chain of calls.
The new block looks like:
def get_form_params():
“”“Stringify GET request parameters.”“”
data = frappe._dict(frappe.local.form_dict)
frappe.desk.reportview.clean_params(data) ← added frappe.desk.reportview. so it will reference the original reportview.py
frappe.desk.reportview.validate_args(data) ← added frappe.desk.reportview. so it will reference the original reportview.py
new_function(data) ← the new function I need to process “data”
return data
I don’t want to copy N functions from reportview.py to override.py because it will be a nightmare to maintain.
I’m kinda stuck.
Any advice?